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above the aircraft, the data tag will be placed above the traffic symbol and preceded by a plus (+) sign and a two-digit

number. For traffic below the aircraft, the data tag will be placed below the traffic symbol and preceded by a minus

(-) sign and a two-digit number. The two-digit number represents the relative altitude of the intruder, proximate, or

other aircraft traffic in relation to own aircraft. For example; a data tag of +21 would indicate that the traffic is 2,100

feet above own aircraft’s present altitude. If an intruder aircraft is either climbing or descending in excess of 500 feet

per minute, an arrow will appear to the immediate right of the traffic symbol. The arrow will point down if the traffic

is descending and will point up if the traffic is climbing.

During a resolution advisory (RA), red and green bands will overlay the vertical speed scale. The bands reflect the

RA in progress and act as vertical speed advisories for the pilot. The red band indicates what vertical speed range

is to be avoided by the pilot. The green band indicates the recommended vertical speed that the pilot is to attain in

order to achieve safe separation from an intruder aircraft. Climb commands are inhibited at or above 24,000 feet for

C-130T aircraft. Climb commands will not exceed a 1,500 FPM climb rate.

DISPLAY

SYMBOL

COLOR

FUNCTION

DEFINITION

Solid Circle

Amber

Traffic Advisory

Intruder aircraft are entering the caution area, 20

(TA)

to 48 seconds from the TCAS collision area. A

visual search is recommended to prepare for

intruder avoidance.

Solid Square

Red

Resolution

Intruder aircraft are entering the warning area, 15

Advisory (RA)

to 35 seconds from the TCAS collision area.

Prompt action is required to avoid the intruder.

Solid Diamond

Blue

Proximate Traffic

Aircraft are within 6.0 nautical miles and +1,200

feet vertically from own aircraft. Proximate traffic

is shown to improve situational awareness in the

event of a potential conflict with other aircraft.

The flightpaths of proximate traffic are not

predicted to enter the TCAS collision area.

Hollow Diamond

Blue

Other Traffic

Aircraft are within the range of the VSI/TRA

display and +2,700 feet vertically from own

aircraft. The flightpaths of other traffic are not

predicted to enter the TCAS collision area.

Figure 2-123. TCAS Traffic Symbology

An off-scale traffic advisory occurs when TCAS is tracking an intruder that is outside the range of the VSI/TRA but

has entered the Caution or Warning areas. One half of the appropriate symbol will appear at the proper bearing at

the edge of the display area. The symbol will appear at the appropriate color and shape and will display a data tag,

provided there is enough room.

If TCAS is unable to track the bearing of an intruder, a no-bearing advisory will appear. The inability to track the

bearing of an intruder is usually caused by temporary antenna shielding due to steep bank angles or by a failure in

the TCAS antennas. TCAS will still be able to compute traffic and resolution advisories. When TCAS is unable to

track the bearing of the intruder aircraft, no symbol will be displayed on the VSI/TRA. Instead, a no-bearing advisory

will appear in alphanumeric form. It will display the acronym “TA” or “RA,” the distance of the intruder from the

own aircraft in nautical miles, and the relative altitude and direction of the intruder from the own aircraft. For

example, an intruder creating a resolution advisory that is 0.6 nautical miles and 600 feet below the own aircraft

would causeadisplay that would read “RA 0.6 -06.”This display will also appearin theappropriate colordepending

on the type of alert.

Current operation modes appear in white letters. The modes include TCAS OFF and TA only. Failure modes appear

in amber letters and displace the current operation modes in case of system failure. The failure modes include TCAS

FAIL, RA FAIL, VSI FAIL, and TA FAIL.

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2.21.21.2.5 TCAS Aural Announcements

TCAS is programmed with 14 aural announcements (see Figure 2-124), excluding test announcements. These 14

announcements alert the aircrew to changing traffic conditions and are broadcast from a cockpit loud speaker as well

as to the flightcrew headsets from the interphone communication system. The aural announcement, TRAFFIC,

TRAFFIC, is generated when a potential traffic threat is approaching. A variety of aural alerts are given when the

first RA of an encounter is displayed and each time a subsequent change in the advisory is displayed, either

strengthened or weakened. The announcements differentiate the advisories by type. The weakened advisory,

MONITOR VERTICAL SPEED, is initiated to facilitate minimizing the vertical deviation from ATC clearances.

An aural announcement also indicates that the aircraft is CLEAR OF CONFLICT. This announcement occurs when

the RA is removed from the VSI/TRA and the intruder aircraft has begun to diverge in range.

2.21.21.2.6 Pilot Responsibilities

TCAS is intended as a backup to visual collision avoidance, application of “right-of-way rules,” and Air Traffic

Control (ATC) separation service. To work effectively, timely and reliable crew response to TCAS advisories is

essential. Flightcrews operating in United States airspace are expected to respond to TCAS in accordance with the

following guidelines. Flightcrews operating in other country’s airspace are expected to familiarize themselves with

any special rules that may be in effect relating to TCAS operations prior to entering that airspace.

Traffic Advisories

Respond immediately to TAs (Traffic Advisories) by attempting to establish visual contact with the intruder aircraft

and other aircraft that may be in the vicinity. If traffic is acquired visually, continue to maintain or attain safe

separation in accordance with good operating practices and current FAR’s (United States Federal Aviation

Regulations) or other applicable air regulations. TA displays and advisories are intended only for assistance in

visually locating the traffic.

Note

D Thepilot should not initiateevasivemaneuvers using information from the

traffic display only, or upon receipt of a Traffic Advisory (TA) only,

without positive visual identification of the traffic.

D Thepilot should reducevertical speed to 1,500 feet perminuteorlesswhen

within 2,000 feet of an ATC directed level-off altitude to reduce the

incidence of unnecessary TAs.

Resolution Advisories

Respond immediately to satisfy Corrective RAs using positive control inputs, in the direction and with the magnitude

TCAS advises, while attempting to sight the conflicting traffic. The aircraft’s vertical speed indication as shown on

the VSI/TRA must be moved out of the RED band and into the GREEN band. Compliance with TCAS Resolution

Advisories (RAs) is necessary and authorized according to United States Federal Air Regulation (FAR 91.123) which

allows pilots to deviate from an ATC clearance if “the deviation is in response to a traffic alert and collision avoidance

system resolution advisory.”Following aTCAS “CLEAR OF CONFLICT”advisory, thepilot should expeditiously

return to the applicable ATC clearance unless otherwise directed, and notify ATC.

For TCAS to properly function, initial vertical speed response is expected within five seconds of an RA. A prompt,

smooth pitch change of 2_ to 6_ should be sufficient to resolve nearly all conflicts. Maneuvering g-forces should be

similarto thosefelt when responding to an ATC clearanceto climb ordescend immediately (0.25g increment).From

level flight, proper response to a TCAS RA typically results in an overall altitude deviation of 300 to 700 feet in order

to successfully resolve a traffic conflict. If possible, visually confirm the necessity and suitability of the avoidance

maneuver but recognize that any other aircraft seen visually may not necessarily be the threat aircraft or the only

aircraft that is triggering the TCAS system response.

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MESSAGE TYPE

AURAL WARNING

MEANING

Traffic Advisories (TA)

“Traffic - Traffic”

TCAS predicts that an intruder aircraft will enter the collision

area within 20 to 48 seconds. Amber solid circle showing the

range and relative bearing on the VSI/TRA.

Preventive Resolution

“Monitor Vertical Speed -

Indicates that certain changes in vertical speed may not be

Advisory (RA)

Monitor Vertical Speed”

safe. Pilot should monitor the vertical speed of the aircraft

and keep the VSI pointer out of the RED area on the VSI

scale.

Corrective Resolution

“Climb - Climb”

The VSI/TRA is RED from the negative limit to +1,500 fpm

Advisories (RA)

and GREEN from +1,500 to +2,000 fpm. Pilot should

immediately climb at the rate indicated by the green arc.

“Descend - Descend”

The VSI/TRA is RED from the positive limit to -1,500 fpm

and GREEN from -1,500 to -2,000 fpm. Pilot should immedi-

ately begin to descend at the rate indicated by the green arc.

“Climb, Crossing Climb -

The VSI/TRA is RED from the negative limit to +1,500 fpm

Climb, Crossing Climb”

and GREEN from +1,500 to +2,000 fpm. Pilot should start to

climb at the rate shown on the VSI. This flightpath will cross

the intruder aircraft’s altitude.

Strengthening Resolution

“Descend, Crossing Descend

The VSI/TRA is RED from the positive limit to -1,500 fpm

Advisories (RA)

- Descend, Crossing

and GREEN from -1,500 to -2,000 fpm. Pilot should start to

Descend”

descend at the rate shown on the VSI. This flightpath will

cross the intruder aircraft’s altitude.

“Adjust Vertical Speed,

The VSI/TRA indicates the prohibited vertical speeds by a

Adjust”

RED arc. The goal is to make the aircraft smoothly attain the

recommended vertical speed indicated by the GREEN arc.

Strengthening Resolution

“Increase Climb - Increase

Inhibited on C-130T aircraft.

Advisories (RA)

Climb”

“Increase Descent -

The VSI/TRA is RED from the positive limit to -2,500 fpm

Increase Descent”

and GREEN from -2,500 to -3,000 fpm. This indicates that

the vertical speed must be increased to ensure adequate

separation. Pilot should immediately increase descent rate

as indicated by the GREEN arc.

“Climb, Climb Now! - Climb,

Indicates that a reversal of vertical speed is necessary to

Climb Now!”

provide vertical separation between the aircraft and an

intruder aircraft. The VSI/TRA is RED from the negative limit

to +1,500 fpm and GREEN from +1,500 to 2,000 fpm.

“Descend, Descend Now! -

Indicates that a reversal of vertical speed is necessary to

Descend, Descend Now!”

provide vertical separation between the aircraft and an

intruder aircraft. The VSI/TRA is RED from the positive limit

to -1,500 fpm and GREEN from -1,500 to -2,000 fpm.

Weakening or Restrictive

“Maintain Vertical Speed,

Indicates vertical speed is not within the RED restricted

Resolution Advisories (RA)

Maintain”

vertical speeds shown on the VSI/TRA. Keep vertical speed

out of the RED unsafe areas as indicated on the VSI/TRA.

“Adjust Vertical Speed,

The VSI/TRA indicates the prohibited vertical speeds by a

Adjust”

RED arc. The goal is to make the aircraft smoothly attain the

recommended vertical speed indicated by the GREEN arc.

“Maintain Vertical Speed,

The VSI/TRA indicates prohibited vertical speeds in RED

Crossing Maintain”

and the target vertical speeds in GREEN. Separation with the

intruder aircraft is adequate if a current vertical speed

commanded is maintained.

Clear of Conflict Advisory

“Clear of Conflict”

The VSI/TRA RED and GREEN arcs are removed. Confirms

that the encounter has ended and separation between the

aircraft and intruder aircraft is increasing. A return to the

original ATC clearance profile is expected.

Figure 2-124. TCAS Aural Announcements

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D During multiple aircraft encounters, when other traffic is above and below

your aircraft, the TCAS computer and the VSI-TRA indicator may give

conflicting information to aircrews. The VSI-TRA indicator may indicate

an RA fail message while the TCAS audio annunciation indicates

“MAINTAIN VERTICAL SPEED, MAINTAIN”. When in this situation

the flight crew shall follow the audio annunciation

“MAINTAIN

VERTICAL SPEED, MAINTAIN” until “CLEAR OF CONFLICT” audio

annunciation has occurred.

D During any airplane configuration that could limit the normal climb

capability of the airplane (such as engine out, ramp open, etc.) or during an

operational situation where a resolution advisory

(RA) maneuver is

prohibited, TCAS should be placed in TA only if used.

CAUTION

D Maneuvering in responseto RAs must bedonemanually by thepilot flying

theaircraft. Autopilot responsetimemay betoo slow toprovidethedesired

separation. Pilots must disconnect the autopilot and establish the proper

pitch attitude manually.

D Altitude excursions to cardinal altitudes not assigned, or beyond that

directed by the TCAS, may compromise the safety of the entire ATC

system and may cause severe and dangerous effects for all aircraft.

D Noncompliance with a Crossing RA by one airplane may result in reduced

vertical separation. Therefore, safe horizontal separation must also be

assured by visual means.

D Once a Non-Crossing RA has been issued, safe separation could be

compromised if current vertical speed direction is changed, except as

necessary to comply with the RA. This is because TCAS-to-TCAS

coordination with the intruder airplane may be in progress and any change

in vertical speed that does not comply with the RA may negate the

effectiveness of the other aircraft’s compliance with the RA.

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Note

D AClimbRAdoesnotmandateaMissedApproach.Thepilotmustexercise

appropriate judgment to assure the airplane is properly configured for the

maneuver, whether it be a subsequent landing or a Go-Around/Missed

Approach. In most cases, the TCAS event will be resolved with only a

minor deviation to the intended flight path and sufficient time and altitude

may exist to recover safely to the desired flight path.

D An Altitude-Crossing maneuver may occur when the intruder or host

aircraft is climbing or descending at a high rate. Under these conditions, the

TCAS logic determines that safe separation is best achieved through an

Altitude-Crossing maneuver. This maneuver will result in the TCAS

aircraft and the intruder crossing through each other’s altitude. This safe

strategy will result in adequate vertical separation between aircraft.

2.21.22 AN/APX-76B IFF Interrogator

The AN/APX-76B IFF interrogator is an air-to-air interrogator that operates in conjunction with the AN/APN-59E

search radar or the AN/APS-133(M) multimode radar. It is capable of generating interrogations on IFF/SIF mode

1, 2, 3/A, or4 anddevelops avideo outputto thesearch radarindicator. Returnsfrom theinterrogated aircraftindicate

theaircraft identification, position in azimuth, and rangefrom interrogatingaircraft. Theinterrogatorsystemconsists

of an IFF interrogator control panel and a display control unit located on the navigator control panel (see Figure

2-125). An IFF interrogator antenna (see Figure 2-83) is mounted on top of the fuselage. The system receives 115-Vac

power from the essential ac bus on, and 28-Vdc power from the essential dc bus through the IFF interrogator circuit

breakers on the copilot upper circuit breaker panel.

2.21.22.1 IFF Interrogator Control Panel

The interrogator control panel (see Figure 2-125) contains the controls, indications, and functions as follows:

1. IFF interrogator controls — See Figure 2-125 for control panel functions.

2. IFF interrogator switch panel controls — Display control unit contains the controls as shown in Figure2-125.

3. Display control unit.

Note

See AN/APS-133(M) multimode radar for an explanation of the remaining

switches on the display control unit.

2.21.22.2 Normal Operation of the IFF Interrogator System

To place the IFF interrogator into operation, proceed as follows:

Note

On the AN/APS-133(M) multimode radar, the radar indicator must be on.

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IFF INTERROGATOR CONTROLS

CONTROL

POSITION

FUNCTION

M4 ALARM OVERRIDE

Allows overriding of the mode 4 alarm, if desired.

Switch

TEST-CHAL CC Switch

TEST

Activates the interrogator for loop testing with the

aircraft IFF transponder.

CHAL CC

Initiates a challenge resulting in correct code dis-

play.

FAULT Light Indicator

Press-to-test and turn-to-dim

When illuminated, advises that there is a fault in

(amber)

the system.

CHAL Light

Press-to-test and turn-to-dim

Light remains on during the length of time

(green)

interrogation is being made.

DISPLAY CONTROL UNIT

IFF Power

PWR-OFF

Connects ac and dc power to the system.

IFF Challenge

CONT-MOM (center OFF

Used to operate the system. Continuous (CONT)

position)

or momentary (MOM) challenge is provided. The

MOM position is spring-loaded to return to the

OFF position.

Note

See AN/APS-133(M) multi-mode radar for an explanation of the remaining switches on the display control unit.

Figure 2-125. AN/APX-76B(V) IFF Interrogator Controls and Indicators (Sheet 2)

On the control panel:

1. Set the mode selector switch to the desired mode.

2. Set the code selector switches to the desired code.

On the AN/APS-133M display control unit:

3. Place the PWR/IFF switch to the ON position.

On the IFF audio monitor panel:

4. Set the copilot interphone IFF audio as desired (see Figure 2-86).

Note

With the CHAL switch on the switch panel in the CONT position

(continuous interrogation), bracket returns (single video slash) can be

eliminated by placing the TEST-CHAL CC switch on the control panel to

CHAL CC, leaving only the correct code (double video slash) returns

displayed.

5. With the AN/APS-133(M) multimode radar in the IFF or IFF/NAV mode, press the TEST-CHAL CC switch

on the IFF interrogator control panel to the CHAL CC position to interrogate aircraft on the correct code.

6. To test the system, set up both the interrogator and transponder system to the same mode and code and press

the TEST-CHAL CC to the TEST position. The interrogation reply of the transponder will appear on the search

radar indicator at approximately a 4-mile range (may be a continuous line).

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2.21.23 FCS 105 Flight Control System

FCS 105 is a combination of autopilot, guidance, displays, and sensors and is made up of two flight directorsystems

(Collins FD 109) and the autopilot (Collins AP-105V). Flight director system Nos. 1 and 2 receive 28-Vdc power

from the essential dc bus through the FLT DIR NO. 1 and FLT DIR NO. 2 circuit breakers located on the copilot

upper circuit breaker panel and 115-Vac power from the essential ac bus through the FLT DIR NO. 1 and FLT DIR

NO. 2 circuit breakers located on the copilot upper circuit breaker panel. The autopilot is powered by 28-Vdc power

from the essential dc bus through the AUTOPILOT PWR and ANN LIGHTS circuit breakers on the copilot lower

circuit breaker panel and 115-Vac power from the essential ac bus through the AUTOPILOT circuit breaker on the

pilot upper circuit breaker panel.

2.21.23.1 Attitude Director Indicator

ADIs present a three-dimensional display of aircraft attitude, steering commands, localizer and glideslope deviation,

rate of turn, aircraft slip or skid, radar altitude, and decision height (see Figure 2-126). When the autopilot is coupled,

the ADI is used to monitor autopilot performance. When the autopilot is not coupled, the pilot uses the display to

manually fly the aircraft. The following paragraphs describe the ADI.

2.21.23.1.1 Aircraft Symbol and Attitude Display

A fixed delta-shaped symbol represents the aircraft. Aircraft pitch and roll attitude is displayed by the relationship

of the aircraft symbol to the movable attitude tape. Pitch indexes are shown on the attitude tape. The pitch attitude

tape is colored with a blue sky above a brown earth separated by a white horizon line; roll indexes show 10_, 20_,

30_, 45_, and 60_ of right and left bank. Two sources of pitch and roll attitude reference are available for use by the

attitude display: gyro attitude (GYRO ATT) or INS attitude (INS ATT). The source is controlled by the attitude select

switches located on the pilot and copilot instrument panel (see Figure 2-129). INS attitude is the primary attitude

reference.

2.21.23.1.2 Command Bars

The command bars display computed pitch and bank commands. These bars move up or down to command a climb

or descent and roll clockwise or counterclockwise to command a right or left bank. Theaircraft is maneuvered in roll

and pitch to align the aircraft symbol and command bars.

2.21.23.1.3 Glideslope Pointer and Scale

The glideslope pointer represents the center of the glideslope beam and displays vertical aircraft displacement from

the glideslope-beam center. The center of the glide-slope scale represents the aircraft. When the pointer is deflected

upward, the aircraft is below the glidepath. This is displacement information only; pitch commands are presented

by the pitch command bars. The glideslope pointer is in view only when the navigation receiver is tuned to a localizer

frequency. It is not in view during a back-course approach.

2.21.23.1.4 Runway Symbol

The rising runway symbol represents a combination of radio altitude and expanded-scale localizer information. It

depicts aircraft altitude relative to the runway during the last 200 feet of descent. Left and right movement displays

the aircraft deviation from localizer center. Full-scale deflection (outside marks) is equivalent to the inner dots on

the HSI (approximately 1-1/4_ from the localizer center-line). Up and down movement is controlled by the

radio/radar altimeter. Vertical movement begins at 200-feet radio/radar altitude and is marked in 50-foot increments.

The symbol comes into view and displays information when a reliable localizer signal is being received.

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2.21.23.1.5 Decision Height Annunciator

On C-130T aircraft prior to 164993, the radar altimeter illuminates the decision height annunciator at the preselected

radar altitude set on the CARA indicator. On C-130T aircraft 164993 and up, the radar altimeter illuminates the pilot

and copilot decision height annunciators at the preselected radar altitude set on the respective (pilot/copilot) CARA

indicator.

2.21.23.1.6 Slip Indicator (Inclinometer)

The slip indicator or inclinometer displays aircraft slip or skid. The inclinometer consists of a weighted ball in a

liquid-filled, curved glass tube.

2.21.23.1.7 Rate-of-Turn Pointer

The rate-of-turn pointer displays aircraft rate of turn about the yaw axis. A two-needle width deviation shows a

standard rateturn of3_persecond;aone-needlewidth deviationshows ahalf-standard rateturn of1-1/2_ persecond.

2.21.23.1.8 Speed Deviation Pointer and Speed Flag

The speed deviation pointer and SPEED flag are used to display the difference between actual aircraft speed and a

computed optimum speed as manually set on the pilot airspeed indicator. When speed exceeds the target speed by

approximately 20 knots, the pointer is deflected out of view. When approximately 20 knots below target speed, the

pointer remains in view. When not in use, the pointer is deflected out of view.

Note

The SPEED flag remains out of view any-time dc power is applied to the

system anddoes notindicateproperoperation ofthesystem.When inview,

it indicates only that power is off.

2.21.23.1.9 Test Switch

TheTEST pushbuttonswitch permitspartial testingoftheADIpitchand rollservo systems.Pressing thispushbutton

causes the attitude display to change by 10_ (+3_) pitchup and 20_ (-5_) right bank. The gyro flag also appears.

2.21.23.1.10 ADI Warning Flags

1. Glideslope (GS) warning flag — When VOR/ILS 1 or VOR/ILS 2 has been selected on the NAV SEL switch

and the receiver set on a localizer frequency, the glideslope warning flag appears when the glideslope deviation

being displayed is unreliable. All glideslope-related vertical commands are unusable while the flag is in view.

The glideslope warning flag is removed from view in the back-course mode.

2. Computer (CMPTR) warning flag — The CMPTR warning flag indicates that any steering commands from

the flight computerto theassociated ADIcommand bars and autopilot (if coupled)are unreliablefor themode

selected. When the flag appears, the command bars go out of view.

3. Runway warning flag — The RUNWAY warning flag indicates that the runway symbol information is

unreliable. An unreliable localizer signal causes the flag to come into view. A CARA malfunction or a failure

of the symbol to follow input signals causes the flag to come into view.

4. GYRO warning flag — The GYRO warning flag indicates that the attitude information being displayed may

be incorrect. The cause of the flag may be because of a malfunction of or loss of power to the vertical reference

furnishing attitude information or internal failure of the attitude display mechanism.

5. Rate of turn (R/T) warning flag — The R/T warning flag indicates that the rate-of-turn pointer is unreliable.

A malfunction of or loss of power to the turn rate gyro will cause the flag to come into view.

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2.21.23.2 Horizontal Situation Indicator

HSIs display a pictorial view of an aircraft with respect to magnetic north, selected course, and selected heading (see

Figure 2-126). Selected heading and course are read against a servo-driven azimuth card. Digital miles and course

displays are provided. Meter movements display course deviation, to-from indication, and glideslope deviation.

Warning flags monitor the azimuth card and navigation and glideslope signals. Remote selection of course and

heading are controlled by the course indicator remote HDG and COURSE control knobs. The following paragraphs

describe the HSI.

2.21.23.2.1 Aircraft Symbol

The aircraft symbol shows aircraft position and heading in relation to the azimuth card, course deviation bar, and

heading marker.

2.21.23.2.2 Azimuth Card

The rotating azimuth card displays magnetic heading information from its respective C-12 compass system. If INS

or Omega is selected with the NAV SEL switch, the card displays heading information from the selected system.

When INS is selected, the heading is true unless modified by a manual conversion to magnetic heading. When Omega

is selected, the heading is true and, during turns, there will be small jumps of the azimuth card because of the delay

in the ONS processing the heading. The jumps will depend upon the rate of turn and, under normal conditions, will

be in very small increments. The heading is read on the azimuth card beneath the lubber line.

2.21.23.2.3 Heading Marker

The heading marker is set to the desired heading as read on the azimuth card by rotating theHDG knob on theremote

heading and course selector control panel.

2.21.23.2.4 Course Arrow

The course arrow is set to the desired course with the COURSE knob on the remote heading and course selector

control panel. When INS or ONS data is displayed, the course arrow is driven to the desired course. The course tail

displays the reciprocal of the course arrow and is read with respect to the azimuth card.

2.21.23.2.5 Course Display

The course display on the upper right corner of the HSI displays a digital readout of course indicated by the course

arrow. When INS or Omega is selected with the NAV SEL switch, the course display will be the desired course.

2.21.23.2.6 Course Deviation Bar

The course deviation bar represents the centerline of the VOR, TACAN, or localizer course. When INS or ONS data

is displayed, the course deviation bar displays crosstrack deviation.

2.21.23.2.7 Miles Display

The miles display on the upper left corner of the HSI provides a digital readout of distance in nautical miles. This

distance information is provided from the No. 1 TACAN system, when operating, for the pilot HSI as long as the

pilot NAV SEL switch is in any position except TAC2 ONSorINS1. Similarly,distanceinformationfrom theNo. 2

TACAN system is displayed on the copilot HSI whenever system No. 2 is operating and the copilot NAV SEL switch

is in any position except TAC 1, ONS, or INS 2. The miles display goes blank when receiving an unreliable distance

signal.

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2.21.23.2.8 To-From Indicator

The to-from indicator reflects the direction to or from the VOR or TACAN station. The indicator arrow is not visible

when a localizer frequency is selected. When the HSI displays INS or ONS data, the to-from indicator reflects the

direction to the TO waypoint.

2.21.23.2.9 Bearing Pointer

When VOR is selected, the diamond-shaped pointer displays bearing to the navigational aid. When INS is selected,

the INS actual track is read against the azimuth card on the “T” end of the pointer.

2.21.23.2.10 Glideslope Pointer

The glideslope pointer represents the center of the glideslope beam and displays glideslope position above or below

theaircraft. When thepointeris abovetheglideslopescalecenterline, theaircraft is below theglideslope. Thepointer

isinviewonlywhenthenavigationreceiveristunedtoavalidlocalizerfrequencyandtheFCS105isnotintheBACK

LOC mode.

2.21.23.2.11 INS Annunciator

The INS annunciator appears when the inertial navigation system is the source of navigation data displayed on the

HSI.

2.21.23.3 HSI Warning Flags

2.21.23.3.1 Heading Warning Flag

The heading warning flag indicates an unreliable heading signal.

2.21.23.3.2 Navigation Warning Flag

The NAV warning flag indicates an unreliable navigation signal.

2.21.23.3.3 Glideslope (GS) Warning Flag

TheGS warning flag indicates an unreliableglideslopesignal. The GS flag is out ofview except when thenavigation

receiver is tuned to a localizer frequency and the FCS 105 is not in BACK LOC mode.

2.21.23.4 Flight Selector (FLT SEL) Panels

FLT SEL panels provide separate mode control over the No. 1 and 2 flight computers (see Figure 2-127). Each flight

selector panel is configured with solenoid-held pushbuttons (push on, push off) used for flight mode selection. An

FCS 105 flight mode can be engaged by depressing the desired mode pushbutton. If the pushbutton remains

depressed, the green ON flag at the bottom of the pushbutton appears and the mode is engaged. Depressing an engaged

pushbutton again will disengage the flight mode. Light intensity for the pushbutton is controlled through the PILOT

CENTER STAND & PILOTS SIDE PANEL lights switch. When a flight mode is engaged, steering commands from

the flight computer will be displayed on the corresponding attitude director indicator command bars. The auto-pilot,

if engaged, can be coupled to either of the two flight computers by depressing the AP CPLD push-button. Once

engaged, the autopilot will accept steering commands from the selected flight computer. HDG and NAV LOC are

lateral modes, and APPR is a combination of both lateral and vertical modes. The ALT SEL (altitude preselect), ALT

(altitude hold), VS (vertical speed hold), and IAS (indicated airspeed hold) are vertical modes and require prior lateral

modeengagement beforethey will engage. When lateral modes, including go-around, arenot engaged, thecommand

bars are out of view, the flight computer is in the off mode, and the autopilot will not couple. Pitch attitude hold

steering is provided when a lateral mode is engaged without a vertical mode being selected. The flight selector

pushbuttons are described in the following paragraphs.

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2.21.23.4.1 AP CPLD

This pushbutton engages theautopilot coupled mode. In this mode, flight computersteering commands for themode

selected will control the autopilot. The flight selector panel on which the pushbutton is depressed determines which

flight computer will control the autopilot. Depressing the opposite AP CPLD pushbutton releases the prior

pushbutton and transfers control to the opposite computer. Disengaging the autopilot releases the AP CPLD

pushbutton.

2.21.23.4.2 HDG

Thispushbuttonengagestheheadingselectmode.Lateral steeringcommands arecontrolled throughtheHSIheading

marker. Maximum bank angle command during this mode is 25_. Depressing the NAV LOC or APPR pushbutton

or selecting the go-around mode automatically disengages the HDG pushbutton.

2.21.23.4.3 NAV LOC

This pushbutton engages a lateral NAV mode. In this mode, a lateral steering command is provided to capture and

track the NAVAID selected by the NAV SEL switch. Prior to the capture point, heading-select-mode steering is

provided. Bank angle commands are limited to 25_ during capture. The bank limit during track is 8_ for VOR, 30_

for INS or ONS, and 15_ for localizer. Depressing either the HDG or APPR pushbutton or selecting the go-around

mode automatically disengages the NAV LOC pushbutton.

2.21.23.4.4 APPR

This pushbutton engages the approach mode, which is the same as NAV LOC mode, with the addition of glideslope

guidance. With ILS selected by the NAV SEL switch, this mode will provide lateral and vertical steering commands

to intercept and track localizer and glideslope beams. Prior to localizer capture, heading select mode steering is

provided. Unless altitude hold is engaged, pitch attitude hold mode is provided. Bank angle limit during localizer

capture is 25_, being reduced to 15_ on track. Following glideslope capture, pitch angle commands are limited to

20_. Depressing the HDG or NAV LOC pushbutton or selecting the go-around mode automatically disengages the

APPR pushbutton.

2.21.23.4.5 ALT SEL

The altitude preselect mode is functional only on the No. 1 flight computer. In the ALT SEL mode, the flight control

system is armed to captureapreselected altitudeas set in thealtitudealerter/preselect control. Inthearmedcondition,

IAS, or VS vertical mode may be selected and flown to capture the selected altitude. The system will remain armed

until the preselected altitude is captured. At capture, the ALT HOLD annunciator light illuminates, a smooth

transition from either ascent or descent is made, and the desired altitude is maintained. After capture, a new altitude

may be selected on the altitude alerter/preselect control and the system will be commanded to ascend or descend to

the newly selected altitude. The ALT SEL mode is automatically released when autopilot controller pitch control is

moved from the detent.

2.21.23.4.6 ALT

This pushbutton engages the altitude hold mode. Vertical steering commands are provided to maintain pressure

altitude present when the pushbutton was depressed. This mode disengages if the existing lateral mode is disengaged,

glideslope capture during ILS occurs, go-around mode is engaged, or the pitch control is moved out of detent prior

to glideslope capture with the autopilot coupled to the flight computer.

2.21.23.4.7 VS

The vertical-speed hold mode is functional only on the No. 1 flight computer. In the VS hold mode, the flight

computer uses pitch attitude and a vertical speed error signal to generate steering commands. These steering

commands are to maintain the vertical speed at which the VS mode was selected. The VS mode is automatically

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released when the glideslope is captured, another vertical mode is selected, or when the flight control system is

engaged and coupled and the autopilot controller pitch control is moved out of the detent.

2.21.23.4.8 IAS

The IAS hold mode is functional only on the No. 1 flight computer. In the IAS hold mode, the flight computer uses

pitch attitude and an indicated airspeed error signal to generate vertical steering commands. These steering

commands are to maintain the indicated airspeed at which the IAS mode was selected. The IAS mode is automatically

released at glideslope capture, when another vertical mode is selected, or when the flight control system is engaged

and coupled and the autopilot controller pitch control is moved out of the detent.

2.21.23.5 Aircraft Control Wheels

Located on the outboard side of the pilot and copilot, control wheels contain a sync (SYN) pushbutton and a

go-around (G/A) pushbutton (see Figure 2-47).

2.21.23.5.1 SYNC (SYN) Pushbutton

The SYN pushbutton is primarily used as an attitude-director indicator function. Its secondary function is to provide

synchronized control wheel steering with the basic autopilot engaged. Each pushbutton separately affects its

respective flight computer only. Pressing a pushbutton when the autopilot is disengaged synchronizes the ADI pitch

command bars with the aircraft attitude. When the sync pushbutton is released, the command bar is referenced to the

aircraft attitude at the moment of release. If agreement between the pilot and copilot ADI is desired, both sync

pushbuttons must be activated at about the same time, or the second one must be activated when the first command

bar is aligned with the aircraft symbol. Pressing a pushbutton during autopilot operation allows the aircraft to be

manually flown to the desired attitude without disengaging the basic autopilot. Upon actuation, the autopilot coupled

and any coupled vertical flight mode will be disengaged. When the sync pushbutton is released, the autopilot coupled

and any desired vertical flight mode must be reengaged. If the flight computer is in the APPR mode, pressing the

SYN pushbutton will have no effect after glideslope capture.

2.21.23.5.2 Go-Around (G/A) Pushbutton

Go-around is selected by pressing the G/A pushbutton on either control wheel. Actuating either push-button

disengages the autopilot, releases all mode pushbuttons on the flight selector panel, and provides signals from the

flight computer to the command bars for a wings-level, 7_ pitchup attitude. The autopilot may then be reengaged,

if desired.

2.21.23.6 Autopilot Controller

Theautopilot controllercontains theyaw damper(YD) and autopilot (AP)engage levers and autopilot turn and pitch

controls (see Figure 2-127). Placing the engage levers to ENGAGED couples the flight control system rudder,

aileron, and elevator servos to the aircraft main surface control-cable system. Autopilot engagement also maintains

automatic pitch trim through the elevator trim tab system.

2.21.23.6.1 Engage Lever

The engage lever is a dual section lever having two positions: ENGAGED and DISENGAGED. This solenoid-held

lever is spring loaded to the DISENGAGED position. The lever is mechanically designed such that the autopilot

cannot be engaged without yaw damper engagement. However, the yaw damper may be engaged independent of the

autopilot lever. (Pilot-initiated autopilot disengagement will release the levers from the solenoid-held ENGAGED

position.) Automatic release occurs if selected attitude reference failure is detected, failure of the servo motors is

detected, system power is lost, manual elevator trim is attempted, or the ELEV TAB power selector switch is moved

from the NORMAL position. The engage lever is the master disconnect for both systems.

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Onaircraft 165313and upwhen disengagingtheautopilotsystem usingthe

control wheel elevator trim (ELEV TRIM) switches, you must manually

select the yaw damper (YD) switch to DISENGAGE prior to landing.

Failure to ensure yaw damper disengagement may cause significant

resistance to pilot-initiated rudder pedal inputs with loss of normal control

authority, damage to the aircraft and injury to personnel. Normal use of the

AP disconnect switches will disengage both the autopilot and yaw damper

switches.

When the autopilot engage lever is in the ENGAGED position, elevator tab control is transferred from the pilot to

the autopilot, allowing the autopilot to automatically maintain pitch trim and preventing abrupt elevator movements

when the autopilot is disengaged.

2.21.23.6.2 PITCH Control

When the autopilot is engaged and not coupled, the PITCH control supplies pitch commands to the autopilot system.

The PITCH control supplies a pitch rate command that increases in proportion to control displacement from the center

detent. Pitchdown is commanded when the control is rotated forward toward DN, and pitchup is commanded when

thecontrol is rotated aft toward UP. Thepitch control is spring loaded to acenterdetent. When engaged, theautopilot

maintains the aircraft pitch attitude that exists when the control is returned to the detent.

Moving the PITCH control out of the detent with the autopilot coupled causes the altitude hold (ALT), altitude

preselect (ALT SEL), indicated airspeed hold (IAS), and vertical speed hold (VS) modes to release, placing the

autopilot and flight computer in the pitch hold mode. The PITCH control is disabled by glide-slope capture.

Note

Refer to paragraph 2.21.23.4 for operation of the attitude select switches.

2.21.23.6.3 TURN Control

When the autopilot is engaged, the TURN control supplies bank command to the autopilot system. It is a roll-rate

command that increases in proportion to the TURN control displacement from the center detent. The TURN control

is also spring loaded to a center detent. Rotating the TURN control out of detent with the autopilot coupled causes

all mode pushbuttons of the respective flight selector to release. Bank-angle limit during turn control operation is

30_. When the aircraft bank attitude is greater than 2_ and the TURN control is returned to the center detent, the

autopilot holds bank attitude. When the aircraft bank attitude is less than 2_ and the control is returned to the detent,

the autopilot remains in heading hold.

2.21.23.7 Autopilot Release Switch

An autopilot release pushbutton switch is installed on both the pilot and copilot control wheels. Pressing either one

ofthepushbutton switches releases theAPand YDswitches, allowingthem toreturn totheDISENGAGEDposition,

disconnecting the servos from each axis.

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Onaircraft 165313and upwhen disengagingtheautopilotsystem usingthe

control wheel elevator trim (ELEV TRIM) switches, you must manually

select the yaw damper (YD) switch to DISENGAGE prior to landing.

Failure to ensure yaw damper disengagement may cause significant

resistance to pilot-initiated rudder pedal inputs with loss of normal control

authority, damage to the aircraft and injury to personnel. Normal use of the

AP disconnect switches will disengage both the autopilot and yaw damper

switches.

2.21.23.8 AP Disengage Reset Switch

The AP DISENG RESET pushbutton switch is located on the annunciator lights test panel (see Figure 2-127). This

pushbutton switch extinguishes the AP DISENG annunciator light.

2.21.23.9 Remote Heading and Course Selector Control Panel

The remote heading and course selector control panels are located on the flight control pedestal (see Figure 2-127).

The HDG and COURSE knobs on each panel position the heading marker and course arrow on the respective HSI.

2.21.23.10 System Annunciator Lights

There are four annunciator light panel assemblies, two annunciator warning or advisory light panels, and two flight

selector mode annunciator panels. One of each of these panels is located on the pilot instrument panel and one each

on the copilot instrument panel (see Figure 2-127). The warning or advisory annunciator lights are as follows:

1. AP DISENG (amber) — Illuminates when the autopilot is disengaged.

2. AP FAIL (red) — Illuminates when monitoring system indicates gyro, power, servo, or internal failure.

3. COMPTR FAIL (red) — Illuminates whenever flight computer or mode input fails. Indicates that the flight

selector panel or failed mode must not be used. Attitude information is still supplied to the ADI and autopilot

for basic gyro mode, provided failure was not because of the gyro.

4. ELEV TRIM (amber) — The elevator servo is sensing an out-of-trim condition. Pilot should expect to see

elevator trim moving to satisfy the trim requirements, at which time the light will extinguish.

5. TRIM FAIL (red) — Illumination indicates the monitoring system is sensing a trim system failure. The pilot

should anticipate an out-of-trim condition upon disengagement of the autopilot.

6. AP CPLD (green) — Illuminates on pilot panel when autopilot is coupled to the No. 1 flight computer and

on copilot panel when coupled to the No. 2 flight computer.

The flight-selector-mode annunciator lights are illuminated to indicate the following:

1. HDG (green) — Bank command is responding to heading marker selection on HSI.

2. ALT HOLD (green) — Pitch command is responding to barometric altitude existing at time of ALT HOLD

engagement.

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3. BACK LOC (green) — Back localizer mode active in NAV LOC. Glideslope pointer and flag are biased out

of view. If APPR is engaged, GS pointer and flags are biased out of view and GS ARM and GS CAPT

annunciator lights are inhibited.

4. NAV ARM (white) — System is set up (armed) for a capture of set course.

5. NAV CAPT (green) — Capture of set course has been initiated.

6. GS ARM (white) — System is set up (armed) for a capture of glideslope.

7. GS CAPT (green) — Glideslope capture has been initiated.

8. G/A (green) — The flight computer is in the go-around mode.

9. ALT ARM (white)— System is armed to captureapreselected altitude. Pitch command is responding to pitch

attitude existing at time of ALT SEL engagement.

10. VS (green) — System is using pitch attitude and a vertical speed error signal to generate steering commands.

11. IAS(green)—System isusing pitchattitudeandan indicatedairspeed errorsignal togenerateverticalsteering

commands.

2.21.23.11 ANNUNCIATOR LIGHTS Test Switch

Theannunciatorlights test switch is located on thepedestal (seeFigure2-127). This three-position switch has TEST,

BRIGHT, and DIM positions.

2.21.23.12 TRIM MONITOR TEST Switch

The TRIM MONITOR TEST switch is located on the pedestal (see Figure 2-127). This switch is used to test the

autopilot automatic trim circuitry and annunciator lights. The test must be performed while the aircraft is on the

ground.

2.21.23.13 NAV SEL Switches

There are two navigation selectorcontrol panels (see Figure2-128) located on thepilot and copilot instrument panel.

Each panel contains a NAV SEL switch. The multiposition NAV SEL switches are provided to connect a navigation

system to the HSIs and the flight control system computers. Eight positions (CDNU, OMEGA INS 3, INS 1 (pilot),

INS 2 (copilot), TAC 1, TAC 2, VOR/ILS 1, VOR/ILS 2, ARA-63) are available on the pilot and copilot switches.

2.21.23.13.1 NAV SEL Switch Modes of Operation

INS Selection

When INS 1 (pilot) or INS 2 (copilot) or INS 3 (if installed) is selected with the corresponding NAV SEL switch,

information from the INS is provided to the flight control system (FSC 105). The course arrow is controlled by the

INS computer to display desired track information. The course deviation indicates cross-track displacement with full

scale (2 dots) being equivalent to 7.5 nm. The azimuth card displays true heading (or magnetic heading when variation

is inserted into the INS) from the INS, and the to-from indicatorreflects direction to theset waypoint. With theNAV

LOC pushbutton on the flight selector panel depressed, the flight computer is placed in the INS NAV mode and

produces guidance commands to capture and maintain the desired track. Two minutes prior to a waypoint the alert

annunciator on the CDU illuminates. If the function selector switch on the CDU is in AUTO, the INS automatically

switches from the present track to the next track at a computed point prior to reaching the waypoint. When this occurs,

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the new course is displayed on the HSI, the alert annunciator extinguishes, and a guidance command is produced to

capture and maintain the new track. If the function selector is in MAN, automatic switching does not occur and the

command is along the extended desired track beyond the waypoint. The alert annunciator light begins to flash

30 seconds prior to reaching a waypoint and continues to flash until the operator initiates a track change.

Figure 2-128. Navigation Selector Control Panels

TAC 1, TAC 2 (TACAN) Selections

With the NAV SEL switch in TAC 1 or TAC 2 and the FLT SEL switch in NAV LOC, the associated flight computer

will be in the NAV LOC mode after capture of the set course (NAV CAPT), using information from the selected

TACAN system that is tuned to the desired station. The course arrow on the associated HSI is set to the selected

TACAN radial to supply a course-error signal (difference between aircraft heading and set course) to the flight

computer and to resolve the signals from the TACAN receiver. The flight computer combines course-error input with

course deviation and bank angle to produce a steering command for display on the ADI command bars and for use

by the autopilot if coupled. This command will provide an asymptotic intercept after capture of the set course (NAV

CAPT). Once on course it will be maintained. When overstation is sensed, bank commands because of course

deviation are minimized and course changes can be made to intercept the new outbound course. The computer

warning flag remains out of view as long as the computer functions properly and is receiving valid information. All

otherflagsintheADIremainout ofview. Informationdisplayed ontheHSIconsists ofcoursedeviationon thecourse

deviation bar, distance to the station on the miles display, and ambiguity on the to-from indicator. The outer mark

(dot) on course deviation scale is equal to 10. The NAV warning flag remains out of view while a valid signal from

the TACAN set is maintained.

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VOL/ILS Selection

With the NAV SEL switch in VOR/ILS I or VOR/ILS 2, and the FLT SEL switch in NAV LOC, the flight computer

will be in the NAV LOC mode when the corresponding NAV receiver is tuned to a VOR or localizer frequency. When

the NAV receiver is tuned to a VOR frequency, information displayed on the HSI and the ADI is the same as described

for TACAN. Distance information is not available unless TACAN is tuned and DME is valid. When the NAV

receiver is tuned to a localizer frequency, the NAV SEL switch is in VOR/ILS 1 or VOR/ILS 2, and the FLT SEL

switch is in APPR, the flight computer selects the ILS mode. The flight computer now uses information from the

localizer and glideslope receivers. The course arrow on the HSI must be set to the inbound localizer course. The ADI

runway flag uncovers the runway symbol as long as valid information is being received and the navigation receiver

and radar altimeter are functioning properly. The glideslope warning flag remains out of view as long as valid

information is being received and the glideslope receiver is functioning properly. Localizer deviation is displayed

by thecoursedeviation baron theHSIand by therunway symbol on the ADI. No ambiguity information is available.

The glideslope pointer continues to give glideslope deviation. The flight computer produces the necessary steering

commands to the ADI command bars and autopilot to intercept and track the localizer and glideslope beam centers.

If the autopilot is coupled, the aircraft will be controlled automatically by the autopilot. The point for start of localizer

capture is variable depending on the intercept angle, rate of closure on beam center, and course deviation. Once this

point is reached, the flight computer combines course error, localizer deviation, and bank angle to capture and then

maintain beam center. Glideslope capture occurs at a fixed glideslope deviation and can be accomplished from above

or below the beam. When the capture point is reached, a pitch up or down command is produced. Once the glideslope

is captured, the flight computer uses the glideslope deviation, normal acceleration, and pitch angle to command a

pitch attitude to maintain beam center. The glideslope signal is desensitized as a function of radar altitude or marker

beacon to reduce the effects of beam narrowing, noise, and bends.

ARA-63 Selection

With the NAV SEL switch in the ARA-63 position, the attitude director indicator command bars will display lateral

and vertical deviations from the optimum approach line.

CDNU Selection

When CDNU is selected with the NAV SEL switch, information from the CDNU is provided to the flight control

system (FSC-105) and HSI. The course arrow is controlled by the CDNU to display desired track information and

distance to the next waypoint will be displayed. Full scale displacement on the course deviation indicator will be

determined by the flight mode. The flight mode is set via the CDNU expanded FPLN page and displayed on the

annunciator panel. Maximum deviations for each mode are as follows:

1. EN ROUTE mode — Full scale deflection on the HSI equals 4.0 nm. NAV invalid flag will appear on HSI

if GPS estimated horizontal error (EHE) exceeds 1,000 meters.

2. TERMINAL mode — Full scale deflection on the HSI equals 1.0 nm. NAV invalid flag will appear on HSI

if GPS EHE exceeds 500 meters.

3. APPROACH mode — Full scale deflection on the HSI equals .3 nm. NAV invalid flag will appear on HSI

if GPS EHE exceeds 100 meters.

The HSI azimuth card will display either true or magnetic heading based on the reference source selected on the

CDNU INAV RNAV page and the to-from indicator will point in the direction of the set waypoint. With the NAV

LOCpushbuttonontheflightselectorpaneldepressed,theflightcomputerproduces guidancecommands tomaintain

the desired track. Upon passing a waypoint, sequencing to follow-on waypoints is automatically controlled by the

CDNU and new track, distance, and guidance commands to capture and maintain the new track are displayed on the

HSI.

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2.21.23.14 Pointer Selector Switch

Pointer selector switches, located on the pilot and copilot instrument panels and on the navigator instrument panel,

are provided to permit selection of the source of information to be displayed on BDHIs. The pilot and copilot can

selectively direct VOR 1 or VOR 2 information on the No. 1 pointer of the VOR/TAC BDHI located on their

respective instrument panels; the navigator can selectively direct TAC 1 or ADF 2 information to the No. 2 pointer

on the ADF/TAC BDHI or can selectively direct VOR 2 or TAC 2 information to the No. 2 pointer of the VOR/TAC

BDHI.

2.21.23.15 SELECTED NAV SYSTEM OFF Indicator

The SELECTED NAV SYSTEM OFF indicator, located on the copilot instrument panel, will illuminate to indicate

that the copilot selection with his NAV SEL switch has been disconnected (see Figure 2-128). Selection of a

VOR/ILS, TAC, ARA-63, or Omega/INS 3 mode by the copilot will be disconnected if the pilot selects the same

mode of operation. For INS mode, the pilot selects No. 1 and the copilot No. 2 exclusively. The SELECTED NAV

SYSTEM OFF indicator is powered through the circuit breaker associated with the system selected by the pilot and

is affected by the interlock relays of both the pilot and copilot NAV SEL switches.

2.21.23.16 Operational Checkout of the FCS 105 Flight Control System

CAUTION

As the autopilot is engaged, hold the control wheel and rudder pedals to

cushion rapid movement against the limit stops. Accomplish the checks

with autopilot engaged as rapidly as practical to avoid servo overheating.

Note

Copilot AC INST switch and the ELEV TAB power switch must be in the

NORMAL position. If the G/A annunciator light(s) is illuminated, press

the SYN pushbutton on the corresponding control wheel to extinguish the

light.

Check flight control system annunciator lights in TEST.

Test both attitude director indicators. Check that the attitude display indicates a change of 10_ ±3_ pitchup

and 20_ ±5_ right bank, and that the gyro warning flag comes into view.

Set both heading markers to the lubber line.

Center all flight controls.

Engage autopilot.

Relax centering force on column. Observe that elevator trim tab is driving nose up and both ELEV TRIM

annunciator lights are illuminated.

Slowly exert a back force on the control column until a nosedown trim direction is observed; hold this column

position. Press and hold the TRIM MONITOR TEST switch. Check that the TRIM FAIL warning annunciator

light starts flashing, the ELEV TRIM annunciator light remains illuminated, and the elevator trim tab begins

driving in the noseup direction. Release TRIM MONITOR TEST switch and observe that the TRIM FAIL light

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extinguishes, the ELEV TRIM light remains illuminated, and the elevator trim tab again moves in the

nosedown direction. Relax back force until the control column is centered.

Depress HDG and ALT pushbutton on both FLT SEL panels. Depress AP CPLD pushbutton on No. 1 FLT

SEL panel. Check that the pilot AP CPLD annunciator light illuminates. Check that the pilot and copilot HDG

and ALT HOLD annunciator lights illuminate.

Move pilot and copilot heading markers 5_ right of the lubber line. Check that the control wheel turns right

and both ADI command bars indicate right bank command. Return both heading markers to lubber line.

10.

Depress AP CPLD pushbutton on No. 2 FLT SEL panel. Check that the copilot AP CPLD annunciator light

illuminates and the pilot AP CPLD annunciator extinguishes.

11.

Move pilot and copilot heading markers 5_ left of the lubber line. Check that the control wheel turns left and

both ADI command bars indicate a left bank command. Return both heading markers to the lubber line.

12.

Depress the pilot G/A pushbutton. Check the following:

a. The YD and AP switches move to the DISENGAGED position.

b. The pilot command bars indicate a 7_ pitchup command above zero attitude reference.

c. The pilot G/A annunciator light illuminates.

d. Both AP DISENG annunciator lights illuminate.

e. HDG and ALT hold annunciator lights extinguish.

13.

Depress the pilot SYN pushbutton. The G/A annunciator light will extinguish and the pilot command bars will

be removed from view.

14.

Engage the autopilot.

15.

Repeat steps 12 and 13 substituting the word “copilot” for “pilot.”

16.

Engage the autopilot and depress the HDG, ALT, and AP CPLD pushbuttons on No. 1 FLT SEL panel. Slowly

rotate the autopilot pitch control toward UP. After aft-column movement, rotate the autopilot pitch control

toward DN. Center column with the autopilot pitch control. Check that the ALT HOLD annunciator light is

extinguished.

17.

Slowly rotate autopilot turn control to the right. After right control wheel movement is observed, rotate

autopilot turn control left past the center detent. After control wheel rotates left past center, check that HDG

and AP CPLD annunciator lights are extinguished.

18.

Depress pilot autopilot release switch. The AP and YD switches will move to the DISENGAGED position

and the AP DISENG annunciator lights will illuminate.

19.

Engage the autopilot.

20.

Repeat step 18 using copilot release.

21.

Depress the AP DISENG reset switch and check that the AP DISENG annunciator light extinguishes.

22.

Zero the elevator trim tab.

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2.21.23.17 Normal Operation of the FCS 105 Flight Control System

Do not operate with the autopilot engaged during takeoff and landing or at

gross weights above 155,000 pounds. During ILS coupled approach, do not

operate with the autopilot engaged below 200 feet AGL.

Theautopilotmaybeusedforfour-orthree-engineoperationduringclimb,cruise,anddescent.Three-enginecoupled

approaches are not recommended. The autopilot is capable of intercepts up to 90_ (75_ during course ILS), but to

enhance intercept performance a maximum of 45_ is recommended.

Before engaging the autopilot:

1. Ensure that all flight control system circuit breakers are in.

2. Ensure that the No. 1 compass and flight control system attitude reference are operating properly.

3. Ensure that the ELEV TAB power selector switch is in the NORMAL position.

4. Trim the aircraft for straight-and-level flight.

Engaging basic autopilot:

1. Position the YD and AP switches to ENGAGED.

Note

Do not press the pilot ADI test pushbutton with the autopilot engaged.

Pressing the pilot ADI test pushbutton may cause a slight autopilot roll

reaction of momentary duration.

2. Maneuver the aircraft with the AP pitch and turn knobs on the autopilot controller.

CAUTION

Disengage autopilot and yaw damper prior to switching attitude reference.

2.21.23.17.1 Autopilot Coupled (AP CPLD)

The basic autopilot can be coupled to either of the two flight computers for automatic lateral and vertical guidance

in a selected flight mode. Coupling occurs with selection ofAP CPLD on oneof therespective FLT SEL panels after

any lateral mode is engaged.

2.21.23.17.2 Selected Heading (AP CPLD)

1. Engage the basic autopilot.

2. Set the heading marker on the HSI to the aircraft heading with the heading control knob.

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3. Depress the HDG pushbutton, then the AP CPLD pushbutton on the FLT SEL panel. The HDG and AP CPLD

annunciator lights illuminate.

4. For aircraft heading control, set the desired heading on the HSI heading marker. The autopilot will turn to and

maintain the set heading. The bank angle is limited to 25_ during selected heading mode.

2.21.23.17.3 VOR or TACAN Navigation (AP CPLD)

1. Engage the basic autopilot.

2. Tune the VHF NAV or TACAN receiver to the correct frequency and select VOR/ILS or TAC with the NAV

SEL switch.

3. Set the desired course on the HSI with the course control knob and set the heading marker to the desired

intercept heading with the HDG control knob.

4. Depress the NAV LOC pushbutton, then the AP CPLD pushbutton on the FLT SEL panel. The HDG, NAV

ARM, and AP CPLD annunciator lights illuminate and the aircraft will assume the selected intercept heading.

5. When the capture point is reached, the aircraft turns to capture the desired course. The HDG and NAV ARM

annunciator lights extinguish and the NAV CAPT annunciator light illuminates. The bank angle limit during

capture is 25_.

6. Onceoncourse,themaximumbankproduced bycoursedeviationis 8_.When passingoveraVOR orTACAN

station, this limit is further reduced to 3_. However, if a course change is made during overstation, a full bank

angle may be obtained since the bank limit caused by course error is 25_.

7. To initiate a new capture or manually place the system on course, depress the HDG pushbutton on the FLT

SEL panel, set the heading marker to the new intercept heading, then depress the NAV LOC pushbutton.

2.21.23.17.4 INS Navigation (AP CPLD)

To establish the aircraft on a desired track, perform the following:

1. Engage the basic autopilot.

2. With the INS set up to provide track information, place the CDU function selector switch to the AUTO

position.

3. Place the NAV SEL switch to the INS position. Observe proper HSI presentation.

4. Set the HSI heading marker to aircraft heading, using the HDG knob on the remote heading and course selector

control panel.

5. Depress NAV LOC pushbutton on the FLT SEL panel. The NAV ARM and HDG annunciator lights

illuminate, indicating that the system is armed for navigation capture.

6. Depress the AP CPLD pushbutton on the appropriate FLT SEL panel and observe that the AP CPLD

annunciator light illuminates. Set intercept angle with the heading marker.

7. When capture is initiated, the NAV ARM and HDG annunciator lights extinguish and the NAV CAPT

annunciator light illuminates. Once capture occurs, the steering is provided directly from the INS through the

flight computer. This INS-generated steering signal is bank limited at 30_.

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8. Two minutes before reaching a waypoint, the alert annunciator legend will illuminate. At 30 seconds prior to

reaching a waypoint, the to-from display will change to the next set of waypoints. When this occurs, the

ALERT annunciator legend extinguishes and the change is displayed on the HSI.

2.21.23.17.5 Altitude Preselect (AP CPLD)

1. Engage basic autopilot.

2. Set the altitude alerter/preselect control at the desired altitude.

3. Select a lateral mode and depress the ALT SEL pushbutton on the No. 1 FLT SEL panel. The ALT ARM

annunciator light illuminates and the command bars will display the command to ascend or descend to capture

the preselected altitude.

4. Depress the AP CPLD pushbutton on the No. 1 FLT SEL panel.

5. When the preselected altitude is captured, the ALT HOLD annunciator light illuminates. Depress the ALT

pushbutton. The ALT ARM annunciator light will extinguish and the ALT HOLD annunciator light remains

illuminated.

2.21.23.17.6 Altitude Hold (AP CPLD)

1. Engage basic autopilot.

2. Select a lateral mode and depress the ALT pushbutton on the FLT SEL panel. The command bars will display

the command to maintain the altitude at the time of selection.

3. Depress the AP CPLD pushbutton on the FLT SEL panel.

2.21.23.17.7 Indicated Airspeed Hold (AP CPLD)

1. Engage basic autopilot.

2. Select a lateral mode and depress the IAS pushbutton on the No. 1 FLT SEL panel. The command bars will

display the vertical steering command to maintain the airspeed at which the IAS mode was selected.

3. Depress the AP CPLD pushbutton on the No. 1 FLT SEL panel.

2.21.23.17.8 Vertical Speed Hold (AP CPLD)

1. Engage basic autopilot.

2. Select a lateral mode and depress the VS push-button on the No. 1 FLT SEL panel. The command bars will

display the vertical steering command to maintain the vertical speed at which the VS mode was selected.

3. Depress the AP CPLD pushbutton on the No. 1 FLT SEL panel.

2.21.23.17.9 ILS Approach (AP CPLD)

1. Tune and identify localizer station on both VHF NAV receivers.

2. Place the NAV SEL switch to VOR/ILS 1 on the pilot navigation selector control panel and VOR/ILS 2 on

the copilot navigation selector control panel.

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Set the course arrows on the HSIs to the published localizer inbound course.

Set decision height on the radar altimeter indicator.

Set HSI heading markers to aircraft heading. Depress the HDG pushbutton on the FLT SEL panels. The HDG

annunciator lights will illuminate.

Engage the basic autopilot and depress the AP CPLD pushbutton on the No. 1 or No. 2 FLT SEL panel. The

AP CPLD annunciator light on the side selected will illuminate.

Depress the ALT pushbutton on the FLT SEL panels when constant altitude is to be maintained. The ALT

HOLD annunciator lights will illuminate.

Depress the VS or IAS pushbutton on the No. 1 FLT SEL panel when constant vertical speed or constant

indicated airspeed is to be maintained. The VS or IAS annunciator light will illuminate as selected.

Use the heading marker to fly the aircraft to the desired intercept angle. Depress the NAV LOC pushbutton

on the FLT SEL panels. The NAV ARM annunciator lights will illuminate.

10.

The aircraft assumes and maintains intercept heading until the capture point is reached, then turns to capture

the localizer course. The NAV ARM and HDG annunciator lights extinguish and the NAV CAPT annunciator

lights illuminate. Once established on localizer course, bank angle is limited to 15_.

11.

Prior to capture of glideslope, depress the APPR pushbutton on the FLT SEL panels. The GS arm annunciator

lights illuminate.

12.

After glideslope capture, monitor ILS progress on the ADI and HSI. The GS CAPT annunciator lights

illuminate, and the ALT HOLD and GS ARM annunciator lights extinguish.

13.

Disengage the autopilot when normal landing is to be executed (no lower than 200 feet AGL).

Note

The ADI command bars should be utilized to monitor the approach;

however, theglide-slopepointers and coursedeviation bars will beutilized

as primary indication for aircraft position when flying ILS.

2.21.23.17.10 Back-Course Localizer (AP CPLD)

1. Engage the basic autopilot.

2. Tune and identify localizer station on both VHF NAV receivers.

3. Place the NAV SEL switch to VOR/ILS 1 on the pilot navigation selector control panel and VOR/ILS 2 on

the copilot navigation selector control panel.

4. Set the course arrow on the HSIs to the published localizer inbound front course.

5. Set minimum descent altitude on the radar altimeter indicator.

6. Set HSI heading markers to aircraft heading. Depress the HDG pushbutton on the FLT SEL panels. The HDG

annunciator lights illuminate.

7. Depress the AP CPLD pushbutton on No. 1 or No. 2 FLT SEL panel. The AP CPLD annunciator light on the

side selected illuminates.

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Depress the ALT pushbutton on the FLT SEL panels when constant altitude is to be maintained. The ALT

HOLD annunciator lights will illuminate.

Use heading marker to fly aircraft to the desired intercept angle.

10.

After established on intercept heading, depress the NAV LOC pushbutton on the FLT SEL panels. The BACK

LOC annunciator lights will illuminate.

Note

When the BACK LOC annunciator light illuminates, the glideslope

pointers and warning flags will be removed from view.

11.

After capture has been initiated, all localizer indications will be the same as a normal ILS. Set heading markers

to back course.

12.

Disengage altitude hold and use the autopilot pitch control on the autopilot controller to establish and maintain

desired rate of descent.

Note

After disengaging ALT HOLD, all pitch indications on command bars are

referenced to a fixed pitch attitude as in paragraph 2.21.23.17.2.

13.

Disengage the autopilot at no lower than 200 feet AGL or before flying over the localizer transmitter.

Note

It is recommended that the HDG mode be used when flying over the

localizer transmitter because of large radio deviations.

2.21.23.17.11 Disengaging the Autopilot

Autopilot control is normally discontinued by either of the following actions:

1. Depressing the pilot or copilot autopilot release switch pushbutton.

2. Placing the YD and AP switches to the DISENGAGED position.

In addition, the autopilot may be disengaged by any of the following methods:

1. Positioning the ELEV TAB power selector switch out of the NORMAL position.

2. Actuating the ELEV TAB switch on the pilot or copilot control wheel.

3. Pulling the AUTOPILOT circuit breaker.

4. Depressing the pilot or copilot G/A pushbutton.

2.21.23.17.12 Attitude Director Indicator (Autopilot Disengaged)

TheADIcommand bars display steering guidancethat can beused by thepilot to control theaircraft manually during

takeoff, initial climb, cruise navigation modes, ILS approaches, and go-around maneuver. To satisfy the commands,

theaircraftmustbemaneuveredsothattheaircraftsymbolisflowninto thecommand barsuntil theyareinalignment.

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2.21.23.17.13 Cruise Modes (NAV LOC)

The procedures and results using the ADI command bar steering during cruise navigation modes are the same as the

autopilot, except the autopilot is disengaged and the pilot controls the aircraft to maintain command bar alignment

with aircraft symbol.

2.21.23.17.14 ILS Approach

The procedures for use of the ADI during ILS operation are the same as autopilot, including indications, except the

autopilot is disengaged and the pilot controls the aircraft to maintain command bar alignment with aircraft symbol

during the approach.

Note

The ADI command bars should be utilized to fly the approach; however,

theglideslopepointersand coursedeviation barswill beutilized asprimary

indicators for aircraft position when flying ILS.

2.21.23.17.15 Back-Course Localizer

The procedures for use of the ADI during back-course localizer operation are the same as autopilot, including

indications, except theautopilot is disengaged and the pilot controls theaircraft to maintain command-baralignment

with aircraft symbol during the approach.

Note

After disengaging the altitude hold mode, all pitch indications on command

bars are referenced to a fixed pitch attitude as in paragraph 2.21.23.17.2.

2.21.23.18 Go-Around

Note

If the flaps fail to retract to 50 percent at initiation of go-around, do not

activate the go-around mode. Manually establish the desired climb.

The go-around mode can be engaged by depressing the G/A pushbutton switch on the control wheel.

1. G/A pushbutton — Depressed.

2. Fly aircraft symbol into command bars. Command bars will command wings level and 7_ nose up.

3. If desired, depress the HDG pushbutton on the FLT SEL panel. The command bars will command bank angles

necessary to follow the heading marker, but the pitch bars will remain at 7_ nose up.

The go-around mode can be disengaged by depressing the SYN pushbutton switch on the control wheel. However,

if this is done before step 3 above, the command bars will be biased out of view.

Note

Depressing either G/A pushbutton will disengage the autopilot. The

corresponding ADI command bars will display go-around command

steering, but the other ADI will not change from the previously selected

mode.

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2.21.23.18.1 SYNC

To maintain afixed pitch attitudeafterapitch attitudechange, depress and releasetheSYN pushbuttonon thecontrol

wheel and fly the aircraft symbol into the command bars.

Note

Depressing and releasing the SYN push-button only affects the correspond-

ing ADI display and will not disengage the autopilot. Pitch sync is

inoperative after glideslope capture.

2.21.24 LTN-72/LN-100 Inertial Navigation System

Two INS are installed on the aircraft. A third system (No. 3 INS) may be installed. The INS is a self-contained

navigational aid that provides accurate navigation and position determination anywhere on the Earth, in any weather,

without the aid of ground-based equipment. Each INS consists of the following units: inertial navigation unit,

inverter, modeselectorunit, control display unit, and switches and indicators.TheINSprovides steeringinformation

to the FCS 105 flight control system for autopilot automatic control and ADI manual control using the indicator

command bar lateral steering. Search mode capability is also available. Position and heading information are also

provided for display on the HSI. Navigation signals from the No. 1 INS are displayed on the pilot ADI and HSI.

Navigation signals from the No. 2 INS are displayed on the copilot ADI and HSI. Navigation signals from the No.

3 INS, if installed, can be displayed on either the pilot or copilot ADI and HSI. The LN-100 INS can be set up to use

GPS velocity and position data for in-flight alignment (IFA) or for automatic position, velocity, and bias updating

in NAV mode. The INS is supplied with 115-Vac power from the essential ac bus through INERTIAL NAV SYS

NO. 1 AND NO. 2 circuit breakers on the copilot upper circuit breaker panel. Each INS is supplied with 26-Vac power

from the essential ac bus through INERTIAL NAV SYS circuit breakers on the pilot upper circuit breaker panel. The

INS is supplied with 28-Vdc power from the essential dc bus through INERTIAL NAV SYS NO. 1 AND NO. 2

circuit breakers on the copilot upper circuit breaker panel. An auxiliary battery is available to provide 28-Vdc power

in the event essential dc bus power is lost. The No. 3 INS, if installed, is supplied with 115-Vac power and 28-Vdc

power from the essential ac and dc buses through OMEGA/INS NO. 3 circuit breakers on the copilot upper circuit

breaker panel.

Note

Provisions for the installation of LN-100 Inertial Navigation Units are only

present in the No. 1 and No. 2 positions.

2.21.24.1 INS Controls

The MSU controls the mode of operation of the INS and is used to energize and align the system before flight (see

Figure 2-129). Located on the MSU panel is a rotary-type selectorswitch that provides themode control for theINS.

Also on this panel are two press-to-test annunciator lights (READY NAV, BATT). The CDU controls the entry of

navigational data into the INS, displays data selected by the CDU display selector switch in two numerical displays,

and provides three annunciators that illuminate as certain failures or events occur. The CDU also controls the

automatic, manual, and remote operational functions with the CDU function selector switch. INU fan or blower

warning lights are provided on the main instrument panel and/or at the navigator station and illuminate when cooling

air is not being supplied to the INU.

2.21.24.1.1 Mode Selector Unit

The No. 1 MSU is located on the flight control pedestal. The No. 2 MSU and No. 3 MSU (if installed), are located

on the navigator control panel. The five-position (OFF, STBY, ALIGN, NAV, ATT REF) MSU mode selector switch

is detented in the NAV position to prevent the INS from inadvertently being switched out of the NAV position. The

knob must be pulled away from the MSU panel before the switch can be moved out of the NAV position. The

following functions are performed for each position of the MSU mode selector switch.

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Figure 2-129. LTN-72/LN-100 Inertial Navigation Controls and Indicators (Sheet 1 of 2)

1. OFF — Power is applied only to the MSU and CDU edge lighting. Primary power to the INS is off.

2. STBY — In standby, INS primary power is applied. While in this position, the navigation tests can be

performed and present position entered. The alignment sequence starts during which the platform cages to the

aircraft axis, and platform temperature stabilization and gyro runup are initiated.

3. ALIGN — The automatic alignment sequence begins, and a platform alignment sequence is initiated. When

theautomaticalignment sequenceis completed, theREADY NAV annunciatorilluminates to indicatethat the

navigate mode may be selected by setting the MSU mode selector switch to NAV. The aircraft must not be

moved when the MSU mode selector switch is set to ALIGN. However, gusty wind conditions and movement

caused by fueling or crew loading do not significantly affect alignment.

4. NAV — In navigate, the aircraft may be moved and/or normal in-flight operations performed.

Note

If the MSU mode selector switch of the LTN-72 INS is moved out of the

NAV position, the INS navigational capability is lost and an alignment

must be performed on the ground. An in-flight alignment can be performed

for the LN-100 INS.

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5. ATT REF — In attitude reference, the INS provides pitch, roll, and platform heading outputs only. No

navigational capability exists, and the CDU numerical displays are blank. Once the switch has been placed

in the ATT REF position, a complete ground alignment must be performed before in-flight navigation will

be available.

6. READY NAV annunciator (green) — When this annunciator illuminates, the INS is ready to perform the

navigation function. Rotating the mode selector switch to NAV will cause the READY NAV annunciator to

extinguish.

7. BATT annunciator (red) — This annunciator illuminates when backup power is less than the minimum

required to operate the INS. The annunciator must be pressed to reset to off when power is restored or it will

remain illuminated as long as sufficient power is available to illuminate the annunciator lamp.

2.21.24.1.2 Control Display Unit

The No. 1 CDU is located on the flight control pedestal. The No. 2 CDU and No. 3 CDU (if installed), are on the

navigator control panel. The controls, numerical displays, and annunciators located on the CDU are used to perform

the following functions.

Display Selector Switch

The CDU display selector is a nine-position, rotary-type switch that controls the selected data to be presented on the

left and right numerical displays. Certain positions of the switch are required during data entries and navigational

changes. The nine positions and functions controlled by this switch are as follows:

Track angle and groundspeed (TK GS) — The track angle being made to the nearest tenth of a degree is shown

on the left numerical display. Groundspeed to the nearest knot is shown on the right numerical display.

Heading and drift angle (HDG DA) — The aircraft true heading to the nearest tenth of a degree is shown on

the left numerical display. Drift angle to the nearest tenth of a degree is shown on the right numerical display.

The R or L preceding the reading indicates that the aircraft present track is to the right or left of the aircraft

heading.

Crosstrack distance and track angle error (XTK TKE) — Crosstrack distance to the nearest tenth of a nautical

mileis shown on theleft numerical display. TheR orL preceding the readout indicates that the aircraft present

position is to the right or left of the desired track. Track angle error to the nearest tenth of a degree is shown

on the right numerical display. The R or L preceding the readout indicates that the present track angle is to

the right or left of the desired track angle.

Present position (POS) — Aircraft present position coordinates in latitude and longitude, to the nearest tenth

of an arc-minute, are shown on the left and right numerical displays, respectively. The readout is frozen to

facilitate position checks by pressing the HOLD pushbutton. The HOLD pushbutton illuminates and remains

illuminated until the display is restarted by pressing the HOLD pushbutton again. The INS continuously

computes position during the display freeze, and, when the display is restarted, correct present position is

shown.

Waypoint positions (WPT) — Waypoint latitude and longitude to the nearest tenth of an arc-minute are shown

on the left and right numerical displays, respectively. WPT selector switch settings 1 through 9 represent the

corresponding waypoint positions that are stored in the digital computer. WPT 0 represents the current aircraft

position anytime it is desired to initiate a track from present position to a waypoint.

Distance and time to waypoint (DIS TIME) — Distance to go to the nearest nautical mile is shown on the left

numerical display and is measured between the aircraft present position and to waypoint of the track being

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navigated. Time to go to the nearest tenth of a minute, up to 480 minutes maximum, is shown on the right

numerical display and is derived from the distance along the desired track and groundspeed along the present

track.

7. Wind direction and speed (WIND) — The wind direction to the nearest degree is shown on the left numerical

display and windspeed to the nearest knot is shown on the right numerical display after manual input of true

airspeed. For the LTN-72 and LN-100 systems, true airspeed will be supplied by the TAS computer and no

operator action is required.

8. Desired track angle (DSR TK STS) — When search pattern parameters are not being entered, desired track

angle measured from true north, from 0.0_ to 360.0_ is shown on the left display. The left display reads 0_

until a track leg is inserted. The right display indicates action codes and alignment status. If the HOLD

pushbutton is depressed, the right display will display the malfunction codes as well as status. After a search

pattern has been initialized, the to/from display, with the display switch set to DSR TK STS, will always

display search status (00, 22, 33, 44, 55, or 66). Also, with the display switch set to DSR TK STS, search

parameters are recalled during search mode operation.

9. Display test (TEST) — The display test enables the operator to verify that the CDU numerical displays, to-from

display, and annunciators are operating correctly. The display test may be performed with the MSU mode

selector switch set to STBY, ALIGN, or NAV.

DIM Control

The DIM controls the intensity of the numerical and to-from displays; intensity can be reduced to zero, causing

displays to extinguish.

Waypoint Selector

When the WPT thumbwheel is set to a waypoint (0 through 9) with the CDU display selector switch positioned to

WPT, the waypoint coordinates will appear on the left and right numerical displays. It is also used during waypoint

data insertion.

TK CHG Pushbutton

Allows initiation of manual track leg change.

To-From Waypoint Display

Displays from waypoint number and to waypoint number of track leg being navigated.

Function Selector Switch

The CDU function selector is a three-position, rotary-type switch. The functions performed at each position of the

switch are as follows:

1. AUTO — Provides automatic sequential track changes at waypoints.

2. MAN — Allows manually initiated track changes to be accomplished.

3. RMT — Used for remote ranging and to display inserted crosstrack offset, inserted TAS, time, and inserted

magnetic variation.

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Numerical Displays

The numerical displays display data selected by the display selector switch.

HOLD Pushbutton

The HOLD pushbutton holds present position on left and right numerical displays or initiates manual updating of

present position.

CLEAR Pushbutton

The CLEAR pushbutton removes entered data if pressed before the INSERT pushbutton is pressed.

Data Keyboard

The data keyboard provides 10 keys (0 through 9) that are used to enter present position and waypoint coordinates

and from-to waypoints along with other data.

INSERT Pushbutton

The INSERT pushbutton transfers entered data into the INS computer when pressed.

ALERT Annunciator (Amber)

The annunciator will illuminate 2 minutes before each approaching to waypoint is reached and then either is

extinguished when a track leg change is automatically made (automatic operation) or flashes to indicate that a track

leg change must be manually initiated (manual operation). When track change is initiated manually, the annunciator

will extinguish.

BATT Annunciator (Amber)

The BATT annunciator illuminates when primary INS power is lost and the system has switched to backup battery

power.

WARN Annunciator (Red)

TheWARN annunciatorilluminates when asystem malfunction occurs or, during thealign mode, flashes to indicate

that incorrect present position latitude is inserted or an INS alignment failure has occurred.

2.21.24.2 Pilot/Copilot INS Control/Indicators

2.21.24.2.1 NAV SEL Switch

The INS position of the NAV SEL switch can be selected to display INS information on the HSI and ADI and for

INS steering when the autopilot is engaged and coupled (refer to paragraph 2.21.23.13.1).

2.21.24.2.2 Horizontal Situation Indicator

When the NAV SEL switch on the instrument selector panel is in the INS position, the INS will provide the following

information to be displayed on the HSI:

1. True heading (TH) — The HSI azimuth card is supplied true heading data from the INS. The heading under

the lubber line is the true heading of the aircraft, unless magnetic variation has been manually inserted in the

computer.

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2. Desired track angle (DSR TRK) — The course arrow on the HSI is supplied desired track angle data from the

INS. This allows the course arrow to be driven to a position on the azimuth card to indicate desired track angle

to be flown. A digital readout of the desired track angle appears in the course display. When a track change

is made, the new track will be automatically displayed.

3. Crosstrack distance (XTK) — The crosstrack distance is supplied to the HSI course deviation bar. A two-dot

course deviation is equivalent to approximately 7.5 nm. The bearing pointer displays present track.

4. To-From — The to-from indicator receives to-from data from the INS to indicate direction to the set waypoint.

The heading and NAV warning flags on the HSI come into view to indicate a failure of the INS heading or navigation

input. These warning flags are controlled by the INS only when INS has been selected with the NAV SEL switch.

2.21.24.2.3 Attitude Director Indicator

The gyro warning flag in the ADIcomes into view to indicate afailure ofthe INS attitude input, if INS ATT has been

selected.

2.21.24.2.4 Attitude Select Switch

An attitude select switch is located on each pilot instrument panel. The switch is a push/push-type switch with either

upper green (INS ATT) portion, which selects the INS as the primary source of attitude reference, or the lower white

(GYRO ATT) portion illuminated at all times. Anytime the switch is momentarily depressed, the opposite light

illuminates and signal source switches as described below.

2.21.24.2.5 Pilot Attitude Select Switch

When GYRO ATT legend is illuminated, the pilot ADI, the No. 1 flight computer, and the autopilot receive roll and

pitch attitude information from vertical gyro No. 1 and the autopilot receives heading information from the No. 1

C-12 compass. When INS ATT is illuminated, the attitude source is switched from vertical gyro No. 1 to INS No.

1 and heading for the autopilot is also furnished by the INS.

Note

When the autopilot is using INS (true heading) input for heading hold and

magnetic heading is displayed on the HSI, a change in magnetic variation

as the flight progresses will produce an apparent change in the heading

being maintained.

2.21.24.2.6 Copilot Attitude Select Switch

When GYRO ATT is illuminated, the copilot ADI and the No. 2 flight computer receive roll and pitch attitude

information from vertical gyro No. 2. When INS ATT is illuminated, they receiveattitude information from INS No.

2.21.24.2.7 INS FAN Warning Lights

The INS FAN warning lights are located on the copilot instrument panel and on the navigator control panel. INS 1

FAN WARN light is on the copilot instrument panel and INS 2 FAN WARN light and INS 3/OMEGA FAN WARN

lightareonthenavigatorcontrolpanel.TheINSFAN WARNlights illuminatewhen coolingairisnot beingsupplied

to the applicable INU.

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2.21.24.3 Initial Operation of the INS

CAUTION

Prior to placing the copilot AC INST SEL switch to the STBY position,

select GYRO ATT and disengage all flight director modes. Do not select

INS ATT while in standby as this will result in damage to the ADI.

2.21.24.3.1 INS FAN Warning

If an INS blower/fan warning light illuminates, visually check the INS cooling fan to determine if the fan is operating.

Check the INS fan warning light probe for correct position. Reposition the probe if necessary. If the INS cooling fan

has stopped, shut down the INS, at pilot discretion, or the system will automatically shut down without damage to

the equipment.

2.21.24.3.2 INS Startup

1. MSU mode selector switch — STBY.

If ATT REF is selected for flight operations on the LTN-72 INS, a 3-minute

period under stable conditions is required to enable the INS inertial

platform to level, prior to relying on the INS for attitude outputs. The time

required for the LN-100 system is 30 seconds.

Note

The MSU mode selector switch should be placed to the ATT REF position

anytime it is not planned to proceed with the alignment procedures for the

purposeofusing theINS navigational capability. WiththeLN-100system,

an in-flight alignment can be performed at a later time. The following

procedures need not be accomplished if the attitude reference mode is

selected for flight operations.

2.21.24.3.3 CDU System Tests

1. Complete the INS STARTUP procedure.

2. CDU function selector switch — MAN.

3. CDU display selector switch — POS.

Note

For the LTN-72 system, verify that the CDU right numerical display

indicates the appropriate program number. The left display should contain

00000N, and the from-to display should be 0, 0. Pressing hold on the

LN-100 system will cause the display to cycle between program number,

program checksum, and date of program assembly.

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CDU display selector switch — TEST.

CDU displays and annunciators — Checked.

Note

Check that left and right numerical displays, degree sign, decimal points,

arc-minute signs, NS and EW, and from-to display are functioning and that

the ALERT, BATT, and WARN annunciators illuminate. All numerical

displays indicate 8.

NAV SEL switch — INS.

Note

D Verify that the heading on the HSI is between 118_ and 122_, the desired

track is between 168_ and 171_, the “T” end of the bearing pointer indicates

between 131_ and 134_, and the course deviation bar displays a crosstrack

deviation of 3.5 nm (one dot) left of track.

D Verify that the ADI attitude warning flag goes out of view.

Place the NAV SEL switch to a position other than INS.

2.21.24.3.4 Present Position Entry

INS STARTUP procedure — Completed.

CDU display selector switch — POS.

Note

If correct present position is displayed, proceed to step 9.

Keyboard pushbutton N or S — Depressed.

Present latitude — Entered.

Note

Starting with the most significant digit, enter latitude to the nearest tenth

ofaminutebypressingthecorrespondingpushbuttononthedatakeyboard.

As each pushbutton is pressed, verify that the corresponding digit is

displayed on the left numerical display as the last significant digit and that

each preceding digit moves one place to the left.

INSERT pushbutton — Depressed.

Keyboard pushbutton W or E — Depressed.

Present longitude — Entered.

INSERT pushbutton — Depressed.

MSU mode selector switch — Align.

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Note

TheREADY NAV annunciatorlegend shall normally illuminate within 18

minutes for the LTN-72 INS and within 4 minutes for the LN-100 INS. Do

not move the aircraft (and for optimum alignment, do not start engines)

until alignment has been completed (i.e., READY NAV annunciator has

illuminated and MSU mode selector switch is rotated to NAV position).

2.21.24.3.5 LTN-72 INS Alignment Status Indications

The status of INS alignment is monitored by placing the CDU display selector switch to DSR TK STS with the MSU

mode selector switch in STBY or ALIGN. The two-digit numeral that appears in the right CDU display is the status

number. The initial status number is 90, which appears when STBY is selected. If INS attitude selection is activated

and the NAV SEL switch is placed to the INS position, the HSI heading and NAV warning flags will come into view

as the display status changes to 80. The heading warning flag will go out of view when the display changes to status

50. After 2 minutes and with the MSU mode selector switch positioned to ALIGN with present position inserted,

the status changes to 70. Status 70 is maintained until INS operating temperature has been reached. Once this occurs,

status is changed to 60. At status 60, the INS roughly determines the accuracy of the present position inserted. If

present position is incorrect, the CDU WARN annunciator begins to flash. If entered present position, when checked,

iscorrect,theflashingannunciatormeansthattheINShasfailed.Ifpresentpositionisincorrect,rotatetheMSUmode

selector switch to OFF and restart alignment procedure with the correct position entered.

CAUTION

If the MSU mode selector switch has just been set to the OFF position, it

should remain in the OFF position for at least 4 minutes before selecting

STBY, or damage to the equipment may result.

Status 50 indicates that present position is satisfactory. Status continues to decrease. When status 02 is reached, or

approximately 6 minutes has elapsed since status 10, the MSU READY NAV annunciator illuminates to indicate

that the system is ready to navigate. If the CDU WARN annunciator begins to flash, check the action code.

2.21.24.3.6 LN-100 Alignment Status Indications

When the display selector is set to DSR TRK STS, the right display indicates alignment status of the LN-100 with

the MSU mode selector switch in STBY or ALIGN. Upon being set to STBY, the status will be 90 and will decrement

to status 02 after present position has been entered and the MSU has been positioned to either ALIGN or NAV.

Note

Although it is recommended that the NAV mode be selected just prior to

flight operations, the mode switch can be set directly to NAV from STBY

as soon as present position coordinates have been inserted. The INU will

automatically enter the NAV mode upon completion of the alignment as

indicated by an 01 status on the CDU right display.

If present position has not been entered, the alignment will be held at status 80. At status 60, the INU tests for Normal

Automatic Alignment. If alignment is within tolerance, the alignment will proceed to status 50 where True Heading

becomes valid and the heading flag goes out of view. If the INU detects a fault in the alignment, the WARN light

on the CDU will begin to flash. After a 4 minute normal alignment time with ALIGN selected on the MSU, the

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READY NAV light will illuminate indicating the alignment was successful and the MSU may now be set to NAV.

If NAV was selected immediately after present position entry was completed, the INU will proceed directly into

Navigate mode without illuminating the READY NAV light.

CAUTION

The LN-100 system defaults to a closed-loop mode during alignment. In

this mode (indicated by a “⊂” on the DSR TK/STS display), the INS

positionwillbeautomaticallyupdatedbyGPSdata.GPSisonlyauthorized

as a back-up to visual navigation; therefore, closed-loop updates shall be

terminated prior to using LN-100 data as a primary means of instrument

navigation or prior to overwater navigation. Refer to paragraph

2.21.24.4.2.

2.21.24.3.7 INS Action Code

With the CDU display selector switch positioned to DSR TK STS and with a possible INS malfunction present, an

action code will appear in the right display to the left of the status code. Should the CDU WARN annunciator

commence flashing with the MSU mode selector switch in ALIGN and the action code is 2, 3, or 6, turn the MSU

mode selector switch to OFF, check the INS circuit breakers, and restart the alignment procedure. If the MSU mode

selector switch is in NAV and the CDU WARN annunciator remains illuminated with an action code 1 displayed,

turn the MSU mode selector switch to OFF. If a warning flag (HEADING, NAV) comes into view on the HSI, without

a CDU WARN annunciator and an action code of 4, do not use the INS steering or display information. After any

failure or repeat failure, determine the malfunction code by pressing the CDU HOLD pushbutton before turning the

MSU mode selector switch to OFF. The malfunction code will appear in place of the action code.

Note

More than one malfunction may exist. Repeated pressing of the CDU

HOLD pushbutton will cause a sequential display of code numbers for all

malfunctions. This should be repeated until the initial malfunction code

reappears.

2.21.24.3.8 Rapid Alignment (LN-100 Only)

A rapid alignment mode is available for use when it is anticipated that the normal four-minute alignment time will

affect mission requirements. A rapid alignment is based on the stored position and heading from a reference

alignment. It is therefore required that a normal alignment be performed as a reference alignment at some time

previous to the need for a rapid alignment and that the aircraft remain stationary during the interval between the

reference alignment and the rapid alignment (i.e., the heading, latitude, and longitude of the aircraft must not change).

A rapid alignment at 70 _F requires about 30 seconds. At the end of Status 70, the status goes directly to Status 02

if in ALIGN mode. If in NAV mode, the status goes directly to Status 01. Navigation performance may be degraded

uptofourmilesperhourfollowingarapidalignment.Toperformarapidalignment,firstperformanormalalignment.

Then set theMSUModeswitchto OFF(MSU mustnot beset totheNAVposition). Afternormal alignment,perform

the following:

1. Set the MSU Mode switch to STBY.

2. Set the CDU Display switch to POS and press HOLD, 9, and then INSERT.

3. Verify that the present position from the reference alignment is displayed on the CDU.

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4. Set the MSU Mode switch to ALIGN.

5. On the MSU, observe that the green READY NAV annunciator illuminates in approximately

0.6 seconds.

2.21.24.3.9 Waypoint Coordinates Entry

INS Startup and present position entry — Completed.

CDU function selector switch — MAN or AUTO.

CDU display selector switch — WPT.

Press TK CHG and INSERT pushbuttons.

WPT selector — As Required.

Note

Theinitialenroutewaypointcoordinatesareenteredintowaypoint1unless

an anticipated return track to point of departure is required, in which case

the initial en route waypoint coordinates are entered into waypoint 2 and

the point of departure waypoint is entered in waypoint 1.

Keyboard pushbutton N or S — Depressed.

First waypoint latitude — Entered.

INSERT pushbutton — Depressed.

Keyboard pushbutton W or E — Entered.

10.

First waypoint longitude — Entered.

11.

INSERT pushbutton — Depressed.

Note

Repeat steps 5 through 11 for subsequent waypoint entries.

2.21.24.3.10 Intersystem Crossfill

Crossfill is a feature that is utilized for multiple INS installations. Waypoint coordinates are entered into any one of

the INS systems and then the waypoints are automatically transmitted to the other INS systems in the aircraft. The

INS selected for entry of the data is referred to as the Master INS. Crossfill can be performed while the aircraft is on

the ground and the MSU mode switches are set to STBY, ALIGN, or NAV. Crossfill can also be performed in flight

with the MSU mode switches set to NAV. Crossfill waypoint coordinates are entered as follows:

1. On the desired Master (transmitting) INS system, set AUTO/MAN/RMT switch on the CDU to RMT. Verify

that the From/To display starts flashing.

2. Press TK CHG and then INSERT on the Master CDU. Verify that the CDU From/To display flashes 00.

3. Repeat steps 1 and 2 for the Slaved (receiving) CDU. Verify that the CDU From/To display flashes 00.

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4. Enter the desired waypoint coordinates into the Master CDU or, if waypoints are already present, reenter any

single waypoint into the Master CDU. This transfer may take up to 18 seconds.

5. Verify that the crossfill was performed by setting the Slaved CDU Display switch to WPT and sequence

through all of the waypoint coordinates. Waypoint coordinates should be the same for all of the INS systems.

6. Set AUTO/MAN/RMT switches on all of the CDUs to AUTO or MAN.

2.21.24.3.11 CDNU to INS Intersystem Crossfill

Waypoint coordinates can be entered into any of the CDNUs and then automatically transferred to any INS in the

aircraft. Waypoint coordinates that are entered into the CDNU Flight Plan are transferred to any INS as follows:

1. Enter waypoints into the CDNU Flight Plan.

2. Access the Waypoint Start Page on the CDNU. Enable the crossfill function.

3. Place the INS to the transfer mode by setting the AUTO/MAN/RMT switch to RMT.

4. Place the CDU Display switch to WPT.

5. Press TK CHG, and then press INSERT. Allow two minutes for waypoint transfer.

6. Compare the CDNU Flight Plan waypoint list with the INS waypoints. The waypoint coordinates should be

the same.

2.21.24.3.12 Status Check

Status check of alignment progress is normally made after waypoint entry; however, it can be accomplished at any

time during system alignment.

1. INS startup, present position entry, and waypoint coordinates entry procedures — Completed.

2. CDU display selector switch — DSR TK STS.

Note

Observe status number on CDU right numerical display. After the status

number decreases to 02 and approximately 6 minutes have elapsed since

start of status 10, the READY NAV annunciator illuminates.

3. READY NAV annunciator — Illuminated.

4. MSU mode selector switch — NAV.

5. READY NAV annunciator — Extinguished.

6. INS alignment — Completed.

CAUTION

The LN-100 system defaults to a closed-loop mode during alignment. In

this mode (indicated by a “⊂” on the DSR TK/STS display), the INS

positionwillbeautomaticallyupdatedbyGPSdata.GPSisonlyauthorized

as a back-up to visual navigation; therefore, closed-loop updates shall be

terminated prior to using LN-100 data as a primary means of instrument

navigation or prior to overwater navigation. Refer to paragraph

2.21.24.4.2.

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Note

D This completes the alignment procedure, and the aircraft can now be

moved.

D If desired, the MSU mode selector switch can be set directly to NAV from

STBY after present position has been inserted. System alignment will

progress normally, except the READY NAV annunciator will not

illuminate when alignment is complete. A 01 status is the only indication

that the system has aligned.

2.21.24.3.13

Attitude Reference Check

1. Attitude select switch — Depressed.

Note

Check that the GYRO ATT legends illuminate, ADI GYRO flags are not

in view, and proper attitude references are displayed.

2. Attitude select switch — Depressed.

Note

Observe that normal INS ATT indications return.

2.21.24.3.14

Initial Track Selection

The initial track selection to a waypoint must be accomplished before INS navigational steering will be provided.

Normally, this would be accomplished in flight after takeoff when cleared to the first waypoint. The selection,

however, may be accomplished on the ground if the after takeoff flightpath makes it convenient to do so. The initial

en route waypoint latitude and longitude should be entered before Initial Track Selection procedures are

accomplished.

To enter the initial track without return to point of departure entry, accomplish the following:

1. Alignment — Completed.

2. CDU function selector switch — As Desired.

3. TK CHG keyboard pushbutton — Depressed.

Note

Verify the TK CHG and INSERT pushbutton legends illuminate and the

from-to display is blank.

4. Keyboard pushbuttons 0, then 1 — Depressed.

Note

Verify that from-to display is 0, 1.

5. INSERT pushbutton — Depressed.

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Note

D Verify that INSERT and TK CHG pushbutton legends extinguish. Verify

that initial desired track is accurate.

D Crosstrack distance and track-angle error (XTK/TKE), distance and time

to next waypoint (DIS/TIME), and desired track angle (DSR TK) data are

not available until the initial track is initiated.

To enter initial track when return to point of departure procedure is used, accomplish the following procedures.

1. CDU function selector switch — As Desired.

2. TK CHG keyboard pushbutton — Depressed.

Note

Verify that TK CHG and INSERT push-button legends illuminate and the

from-to display is blank.

3. Keyboard pushbuttons 0, then 2 — Depressed.

Note

Verify that from-to display is 0, 2.

4. INSERT pushbutton — Depressed.

Note

D Verify that INSERT and TK CHG pushbutton legends extinguish. Verify

that initial desired track is accurate.

D Crosstrack distance and track-angle (XTK/TKE), distance and time to next

waypoint (DIS/TIME), and desired track angle (DSR TK) data are not

available until the initial track is initiated.

2.21.24.3.15 Taxi Speed/Track Angle Monitoring

The INS displays taxi speed when taxi speed exceeds 1 knot and displays meaningful track angle indications at taxi

speeds in excess of 10 knots. Track angle and heading displays are the same at taxi speeds less than 10 knots.

1. CDU display selector switch — TK GS.

Note

Read groundspeed to the nearest knot from the right numerical display.

Read track-angle to the nearest tenth of a degree from the left numerical

display.

2.21.24.4 ln-Flight Operation of the INS

The terms automatic and manual, as used in these procedures, apply only to track selection. When in the navigate

mode, the INS provides the same navigation data whether the CDU function selector switch is set to AUTO

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(automatic) or MAN (manual). During automatic operation, the INS navigates through each selected waypoint in

sequence and automatically changes track at each waypoint. During manual operation, the INS navigates from

waypoint to waypoint, but the operator must initiate a track change at each waypoint. CDU display selection and

waypoint position entries may be accomplished with the CDU function selector switch set to either AUTO or MAN.

2.21.24.4.1 In-Flight Warn Indications

The INS provides integral warn indications and signals that cause aircraft instruments to provide warn indications

pertaining to INS operation. These warn indications are as follows.

INS WARN Indications

If the WARN annunciator illuminates, the INS is malfunctioning and may not be providing accurate data. Refer to

paragraph 2.21.24.4.3 for operating procedures.

Aircraft Instrument Warn Indications

The INS provides signals that cause aircraft instruments to provide warn indications as follows:

WARN SIGNAL

WARN INDICATION

Pitch or roll

ADI altitude warning flag

HSI

ADI course warning flag

If the MSU mode selector switch is set to ATT REF, the INS attitude

outputs must not beused until theaircraft hasbeen flownin thewings-level

attitude at a constant speed for the first 3 minutes after ATT REF is selected

to allow the INS inertial platform to complete a level sequence. If this

procedure is not followed, erroneous INS attitude outputs may occur.

Note

D Do not set the MSU mode selector switch on the LTN-72 INS out of NAV

unless an INS malfunction occurs. If the INS is switched out of NAV, the

NAV MODE cannot be reset in flight, as the INS must be aligned on the

ground. An in-flight alignment may be performed for the LN-100 INS.

D If the CDU BATT annunciator illuminates, the INS is operating on dc

backup power. The dc backup power is a battery unit with approximately

2 hours duration for INS operation. The No.

3 INU battery is a

nickel-cadium unit packaged in a metal case. The battery has a

6.5-ampere-hour capacity, which is sufficient to operate the system for 15

minutes. A battery trickle charger is included in the No.

3 inertial

navigation unit to maintain full battery capacity when the system is

operating from 400-Hz power. Action must be taken to substitute for the

INS, particularly if the INS is providing information for automatic flight

control of the aircraft.

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Note

If the MSU BATT annunciator illuminates, the dc backup power is less than

the minimum required to operate the INS. Automatic INS shutdown will

occur, and the warn annunciator will illuminate. The MSU mode selector

switch should be set to OFF if the MSU BATT annunciator illuminates. If

normal poweris restored, ground alignment,in-flight alignment(LN-100),

or in-flight leveling may be attempted a maximum of three times.

2.21.24.4.2 GPS Aided Operations

The INS can be updated in NAV mode utilizing GPS data. Navigation updates are performed in either closed loop

mode(whereGPS datais used to updateposition, velocity, platform tilts, and gyro biases)or open loop mode(where

inertial solutions are maintained in the computer separate from the GPS updated solution). The LN-100 INS can be

aligned during flight. In-flight alignments can only be performed in a closed loop mode. During normal ground

alignment, by default, the LN-100 INS will be aided by GPS in closed loop (Align status will indicate 02) when

valid GPS data is available. With the INS in NAV, open or closed loop GPS updating can be enabled, terminated

and flushed as required. When GPS updating is terminated, the CDU displays and data bus parameters are returned

to free inertial outputs.

CAUTION

GPS is only authorized as a back-up to visual navigation. Closed loop mode

shall be terminated prior to using INS data as a primary means of instrument

navigation or for overwater navigation.

Navigation Updates

All GPS aided operations are under CDU control and several status and advisory displays are available. Both control

and display are performed with the CDU Display Switch in the DSR TK/STS position. Basic GPS mode data is

provided in the space between the action/malfunction code and the system status, with ∪ indicating open loop and

 indicating closed loop operation. For example: ∪01 indicates GPS open loop aided NAV mode. 01 indicates

GPS closed loop aided NAV mode. GPS mode control and additional status displays are enabled by pressing the 1

key on the CDU, which causes the left display to blank and the right display to display status. After pressing the 1

key, the mode selection entry codes are as follows:

1 key

Enable open loop update.

2 key

Enable closed loop update.

5 key

Terminate open or closed loop updates.

9 key

Flush open loop updates.

The left display provides visual confirmation of mode selection in the fifth (from left) digit. After selecting the

required mode, press INSERT to enable or disable GPS aiding. The previous display will return.

To enable open loop update:

1. Set CDU Display Switch to DSR TK/STS.

2. Press 1, the left display blanks and INSERT light illuminates.

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3. Press 1 and verify the left display is 1.

4. Press INSERT and verify INSERT light extinguishes, left display is DSR TK, and right display is ∪01.

5. Ifthe∪ does not appear(STSdisplay is01), press1 toobtain theupdatestatusdisplay. PressCLEAR torevert

to standard DSR TK/STS.

To enable closed loop update:

1. Set CDU Display Switch to DSR TK/STS.

2. Press 1, the left display blanks and INSERT light illuminates.

3. Press 2 and verify the left display is 2.

4. Press INSERT and verify INSERT light extinguishes, left display is DSR TK, and right display is 01.

5. Ifthe does not appear(STSdisplay is01), press1 toobtain theupdatestatusdisplay. PressCLEAR torevert

to standard DSR TK/STS.

To terminate open and closed loop updates:

1. Set display switch to DSR TK/STS.

2. Press 1, the left display blanks and INSERT light illuminates.

3. Press 5 and verify the left display is 5.

4. Press INSERT and verify INSERT light extinguishes, left display is DSR TK, and right display is 01.

To terminate and flush open loop updates:

1. Set display switch to DSR TK/STS.

2. Press 1, the left display blanks and INSERT light illuminates.

3. Press 9 and verify the left display is 9.

4. Press INSERT and verify INSERT light extinguishes, left display is DSR TK, and right display is 01.

In-Flight Alignment (IFA) (LN-100 Only)

The LN-100 may be aligned by one of three methods:

1. Normal Ground Alignment.

2. In-Flight Align (IFA). Alignment is initiated and completed during flight.

3. Hybrid Align. Alignment is started on the ground with the aircraft stationary and completed during taxi or in

flight.

Note

The preferred operational procedure is to perform a normal ground

alignment, allowing the system to enter NAV mode.

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In-Flight Alignment can be used when preflight time does not allow a normal ground alignment or the operator desires

to realign the system during flight. A system can be realigned in flight by recycling the MSU to OFF then to STBY.

Cycling through the OFF mode will allow the LN-100 to perform a fast level during Status 90 at turn on, thereby

removing any large platform tilt errors that may have occurred. If a large position error is not present, the MSU can

becycledtoSTBYwithoutgoingtoOFF.GPSwillinitializethesystempositionandnopositionentrybytheoperator

is necessary. When IFA is initiated, the system will remain in Air Align Hold mode with the CDU displaying align

status 80, with no # present, until both of the following conditions are met:

1. GPS ground speed is greater than 20 knots.

2. Alignment time is less than 85 seconds.

When these conditions are met the system will exit Air Align Hold mode, sequence to align status 70, and initialize

position and velocity from the GPS values. 70 indicates that GPS updating is enabled and proceeding. If the 

does not appear, updates are being rejected. Press CLEAR to revert to standard DSR TK/STS.

If possible, aircraft maneuvers should be restricted to straight and level flight until about one minute after status 70

has been achieved. Moderate aircraft maneuvering thereafter is desirable and will speed the alignment. During a

maneuver that exceeds the acceleration and heading rate limits, GPS updates will not be accepted and a status code

1 2 b b 2 (Acceleration/Heading Rate Excessive) will be displayed. Approximately 15 seconds after completion of

the excessive maneuver GPS updates will again be allowed.

IFA can be enabled during any part of a ground alignment if it is necessary to complete the alignment with the aircraft

moving. This procedure is termed a Hybrid IFA. For an IFA initiated during align status 70, the system will enter

Air Align Hold until GPS ground speed exceeds 20 knots. For an IFA initiated after status 70, the 20 knot limitation

does not apply.

When the alignment is complete, STS display is 02 and the READY NAV light illuminates. The system may be

left in ALIGN mode or may be switched to NAV mode. Alternatively the MSU can be cycled directly to NAV after

IFA is enabled. If an IFA is terminated by the operator prior to the system sequencing to NAV mode then the align

status will be reset to status 80 and Action Code 3/22 (Enter Present Position) will be displayed until the MSU is

switched to STBY.

Note

If the system is left in ALIGN, the LN-100 remains in closed loop update

mode and continues to align the system based on GPS inputs. If thesystem

is switched to NAV, two separate navigation solutions are maintained in

theLN-100 computer, oneinertial and theotherfrom theKalman filterbest

estimate based on INU and GPS measurements. By default, GPS-aided

data is displayed on the CDU. Switching to NAV is recommended to

prevent possible corruption of the alignment from loss of lock conditions.

IFA procedures are as follows:

1. Set CDU Display Switch to DSR TK/STS.

2. Press 1 and verify left display blanks and INSERT illuminates.

3. Press 2 and verify a 2 is displayed.

4. Press INSERT. The display reverts to standard DSR TK/STS with either align status 90 or 80 displayed.

5. Set MSU to ALIGN.

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6. When STS display indicates 02 and READY NAV light illuminates, set MSU to NAV.

7. Terminate and flush closed loop updates.

8. Perform manual position update with an accurate known position fix.

2.21.24.4.3 Attitude Reference Selection

When only pitch, roll, and platform heading outputs are required and navigational capability is not necessary, the

INS can be operated in the attitude reference mode.

Note

To ensure that the INS inertial platform is level, keep the aircraft stationary

or taxiing at a constant speed and a steady course for 3 minutes after placing

the INS mode selector switch to the ATT REF position.

1. MSU mode selector switch — ATT REF.

Note

The MSU mode selector switch is detented in the NAV position and the

knob must be pulled away from the MSU panel before the mode selector

switch can be moved through the NAV position.

2.21.24.4.4 Initial Track Selection

1. Without return to point of departure — Perform same procedure as outlined for ground initial track selection

(without return to point of departure entry). When the INSERT pushbutton is depressed, steering is provided

from aircraft present in-flight position (WPT 0) to waypoint 1.

2. With return to point ofdeparture—Perform sameprocedureasoutlined forground initialtrack selection(with

return to point of departure entry). When the INSERT pushbutton is depressed, steering will be provided from

the aircraft in-flight position (WPT 0) to waypoint 2.

2.21.24.4.5 Flight Plan and Update Changes

Anormal flight plan includes several flight legs. TheINS is capableofstoring ninewaypoint coordinatesat onetime.

When the system is operating automatically, the navigation will be sequential through each waypoint as indicated

on the from-to display, thereby producing automatic sequential track steering. During manual operation, the desired

from-to waypoints are manually inserted, and the track steering associated with these waypoints will be produced.

2.21.24.4.6 Automatic Track Switching at Waypoint

Automatic track switching at a point prior to reaching a waypoint is provided when the CDU function selector switch

is in theAUTO position. When this track switching point is reached, theINS automatically changes to the next track,

the new leg (track) is displayed in the from-to display, steering to the new track is supplied, and the ALERT

annunciator extinguishes. This operation will continue sequentially through each waypoint. Should a new track be

established manually, such as between waypoints 2 and 4, and the CDU function selector switch is returned to AUTO,

automatic switching at waypoint 4 occurs. The new track between waypoints 4 and 5 is established and automatic

sequential track switching will resume.

2.21.24.4.7 Manual Track Switching at Waypoint

When the CDU function selector switch is in the MAN position, a track change to the next desired track must be

accomplished manually by the pilot as the waypoint is approached. To accomplish this operation, the following

operations would be performed:

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1. CDU function selector switch — MAN.

2. TK CHG keyboard pushbutton — Depressed.

Note

After TK CHG pushbutton is depressed, the TK CHG and INSERT

pushbutton legends will be illuminated.

3. Keyboard pushbuttons — Depressed.

Note

Depress the next from waypoint numerical keyboard pushbutton, then

depress the next to waypoint numerical keyboard pushbutton.

4. INSERT pushbutton — Depressed.

Note

When the INSERT pushbutton is depressed, a track change is initiated;

steering to the next track is produced and the new track will be displayed.

As long as the manual function is used, a new track will haveto beinserted

manually at each waypoint.

2.21.24.4.8 Waypoint Bypassing from Present Position

The operator can bypass a waypoint or a number of waypoints from present position at any time. Assume theaircraft

is on a from-to track of 1, 2 and it is necessary to fly from present position to waypoint 3.

1. CDU function selector switch — As Desired.

2. TK CHG keyboard pushbutton — Depressed.

3. TK CHG and INSERT pushbutton legends — Illuminated.

4. Keyboard pushbutton 0, then 3 — Depressed.

5. INSERT pushbutton — Depressed.

Note

D When the INSERT pushbutton is depressed, steering from present position

to waypoint 3 will be initiated and the new from-to track of 0, 3 will appear

in the from-to display.

D If the CDU function selector switch is set to AUTO, automatic switching

occurs as the next waypoint is reached and the from-to track of 3, 4 becomes

the new desired track.

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2.21.24.4.9 Intermediate Waypoint Bypassing

The operator can bypass one or more waypoints by performing certain manual operations on the CDU. Forexample,

assume the aircraft is on a from-to track of 1, 2 and is midway to waypoint 2. A decision is made to bypass waypoint

3 and go directly from waypoint 2 to waypoint 4. The following manual operation will be performed:

1. CDU function selector switch — As Desired.

2. TK CHG keyboard pushbutton — Depressed.

3. TK CHG and INSERT pushbutton legends — Illuminated.

4. Keyboard pushbutton 2, then 4 — Depressed.

5. INSERT pushbutton — Depressed.

Note

When the INSERT pushbutton is depressed, the programmed from-to track

between 2 and 3 is deleted, a new from-to track between 2 and 4 is

established, and steering to the new track is provided. Normally, the track

change would not be initiated until at or near waypoint 2.

2.21.24.4.10 Track Offset

This mode allows the operator to fly a track parallel to the present track at a fixed offset distance. This distance will

be set in by the operator. To enter this mode, the following operation will be performed.

1. CDU display selector switch — XTK/TKE.

2. Keyboard pushbutton 1 — Depressed.

Note

D Observe that the left CDU display goes blank and INSERT pushbutton

legend is illuminated.

D Left 5.3 nm will be used as an example.

3. In sequence, press L, 5, and 3 keyboard pushbuttons — Depressed.

Note

The left display will indicate L 5.3. For a right effect, use R in place of L.

Track offset must be entered to the nearest tenth of a nautical mile.

4. INSERT pushbutton — Depressed.

Verify that correct offset distance is displayed prior to depressing the INSERT pushbutton. After insertion, the right

display will display crosstrack distance from the original track and steering to the offset track. As the aircraft is flown

to the offset track, the crosstrack distance will begin to increase (as shown in left display) and the track-angle error

(right display) steadily increases from the value prior to offset track insertion. As the new track is intercepted, steering

will be produced to allow the aircraft to be flown to and maintain the offset track. When on offset track, the offset

distance (L 005.3) is displayed in the left display and track-angle error is displayed in the right display.

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To return to original track, accomplish the following operations:

5. CDU display selector switch — XTK/TKE.

6. In sequence, press 1, L or R, and INSERT pushbuttons.

Note

Steering is provided to return the aircraft to the original track.

2.21.24.4.11 Waypoint Position Change

The operator can change the coordinates of waypoints or use past waypoint storage locations as future waypoints.

Enter waypoints as described in paragraph 2.21.24.3.9. If past waypoint storage locations are to be used as future

waypoints, enter future waypoints sequentially, starting with 1 and continuing through the last number used to permit

automatic sequential switching.

2.21.24.4.12 Flight Plan Change Between Waypoints

A flight plan change to a new waypoint or destination can be initiated at any time between waypoints. Assume the

aircraft is between waypoints 3 and 4, and it becomes necessary to fly direct from present position to the new

destination. Assuming the destination to be waypoint 7, insert new waypoint 7 latitude and longitude, using the

Waypoint Coordinates Entry procedure. Use waypoint bypassing from present position procedure to insert new track,

0, 7 into system. When INSERT pushbutton is depressed, the new from-to track will beinitiated and the new from-to

track of 0, 7 will appear in the from-to display.

2.21.24.4.13 INS Track Select Mode

The operator can initiate an INS track select mode of operation (referenced to true north from the aircraft present track,

rather than a track between waypoints). By this method, the pilot may fly the aircraft off track.

1. CDU display selector switch — DSR TK STS.

2. CDU function selector switch — MAN.

3. Keyboard pushbutton 0 — Depressed.

Note

Verify that left numerical and from-to displays are blank and that the

INSERT pushbutton legend illuminates.

4. Enter desired track angle to the nearest tenth of a degree on the data keyboard.

Note

Verify that left numerical display is the track angle entered.

5. INSERT pushbutton — Depressed.

Note

Verify that INSERT pushbutton legend extinguishes, the from-to display

is 9, 9 and the DIS/TIME and XTK numerical displays are all zeros.

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The aircraft will turn and fly along a line parallel to the inserted track at the point of insertion. The lateral displacement

from this line is determined by the maximum roll rate commanded, aircraft speed, and autopilot characteristics. The

aircraft will maintain the inserted track.

6. When desired, return to previous mode by initiating the next track change.

2.21.24.4.14 Position Update, Check, and Selection

At any time during flight, the INS present position can be updated to a position fix apparently more accurate than

the inertially derived position. Present position can be updated a maximum 30 arc-minutes in both latitude and

longitude for any one update. The INS retains the original updated present position forthe duration of thenavigation

mode, thereby permitting future comparison of updated with nonupdated positions. If in a future comparison, the

nonupdated position proves more accurate than the updated position, the system may drop the updated position and

revert to the nonupdated position. In the following procedure, when the CDU HOLD pushbutton is pressed, the

present position display freezes. The INS, however, automatically compensates for position changes during this

display freeze.

2.21.24.4.15 Position Update

1. CDU HOLD pushbutton — Depressed.

2. CDU display selector switch — POS.

If update is not necessary, proceed to step 3; if necessary, proceed to step 4.

3. CDU HOLD pushbutton — Depressed.

Note

Step 3 restores display to normal operation.

4. Latitude and longitude of fix position — Entered.

Refer to steps 3 through 8 of paragraph 2.21.24.3.4, noting that the original (nonupdated) coordinate will appear on

the numerical display when the INSERT pushbutton is pressed and will not be updated until the second coordinate

is inserted or the CDU HOLD pushbutton is pressed.

If both latitude and longitude have been updated, numerical displays will restart when the INSERT pushbutton is

pressed the second time. If only latitude or longitude is updated, press the CDU HOLD pushbutton to restart the

display. The CDU HOLD pushbutton legend extinguishes, position changes that occurred during the display freeze

and updating procedures are automatically compensated for, and position display reflects new present position

referenced from updated coordinates.

2.21.24.4.16 Position Update Check

Check the position update versus nonupdated position as follows:

1. At known waypoint, CDU HOLD pushbutton — Depressed.

2. CDU display selector switch — POS.

The display will indicate the frozen value of present position with update (if applicable). With this position noted,

a comparison with a known point (waypoint) can be accomplished by proceeding to the next step.

3. CDU display selector switch — WPT.

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Verify that coordinates of nonupdated position appear in the numerical displays. If updated position is more accurate

than nonupdated position, restart displays by pressing the CDU HOLD pushbutton. The updated position will

continue to be displayed when the display selector switch is set to POS.

2.21.24.4.17 Update Removal

If the non-updated position is more accurate than the updated position, remove the updated position by performing

the following steps.

1. CDU HOLD pushbutton — Depressed (if not illuminated).

2. CDU display selector switch — DSR TK/STS.

3. Keyboard O/DTK pushbutton — Depressed.

4. INSERT pushbutton — Depressed.

Note

If track is being flown from present position to any waypoint, reinitiate

track to pick up new 0 position. If a track hold mode is being flown,

reinitiate the track hold procedure.

TheCDU HOLD pushbutton legend extinguishes, and the nonupdated position will be displayed when CDU display

selector switch is set to POS.

A new updated position can be entered at any time during the navigation mode by performing steps

2 through 8 of

paragraph 2.21.24.3.4.

2.21.24.4.18 True Airspeed and Time Entry and Display

Note

True airspeed is supplied to the INS by a TAS computer. In order to obtain

TAS inputs to the INS from the TAS computer, a zero TAS must be entered

manually. In the event that the TAS goes invalid, the TAS may be entered

manually.

Enter the true airspeed and time data as follows:

1. CDU function selector switch — RMT.

2. CDU display selector switch — WIND.

3. Keyboard DTK pushbutton — Depressed.

Note

Verify that the INSERT pushbutton legend illuminates.

4. True airspeed — Entered.

5. If the true airspeed display is correct, press the INSERT pushbutton.

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6. If the true airspeed display is incorrect, press the CLEAR pushbutton and repeat steps 3 through 5.

7. Keyboard pushbutton 5 — Depressed.

Note

Verify that the INSERT pushbutton legend illuminates.

8. Time — Entered.

9. If time display is correct, press the INSERT pushbutton.

10. If time display is incorrect, press the CLEAR pushbutton and repeat steps 7 through 9.

Note

True airspeed and time can be displayed by setting the CDU function

selector switch to RMT and the CDU display selector switch to WIND. Last

entered values of true airspeed and current time will be displayed.

2.21.24.4.19 Magnetic Heading Entry and Display

The magnetic heading is displayed on the CDU left display and HSI whenever a manual entry of the magnetic

variation has been entered. Determine the magnetic variation for present position, then accomplish the following

procedure for magnetic variation entry.

CDU function selector switch — RMT.

CDU display selector switch — HDG DA.

Keyboard pushbutton W or E — Depressed.

Note

If direction of variation is west, depress W; for east, depress E.

Degrees of magnetic variation — Entered.

Note

Verify magnetic heading in the left display and magnetic variation in the

right display.

INSERT pushbutton — Depressed.

Note

D A zero will appear as the extreme left character of the right display when

true heading is being displayed. A 1 will appear when magnetic heading is

being displayed.

D If correct magnetic heading is to be maintained, it will be necessary to

update the INS as variation changes.

To remove magnetic heading, accomplish Magnetic Heading Entry procedure except that a zero variation is entered

in step 4.

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2.21.24.4.20 Wind Computation

The wind display is blank until TAS is entered or the computer (if installed) accepts computed true airspeed. If the

TAS computer is available, manually zero the TAS to get the computer to accept manual insertion. Refer to paragraph

2.21.24.4.18.

2.21.24.4.21 Distance/Time Along Flight Plan Route

The cumulativedistance and time along the flight plan routefrom present position to any waypoint can bedisplayed.

This can beobtained on theground as well as in flight, as long as theMSU modeselectorswitch is in STBY, ALIGN,

or NAV with present position and route to be flown entered. To obtain this distance and time, perform the following

manual operation:

1. CDU function selector switch — RMT.

2. Keyboard TK CHG pushbutton — Depressed.

3. Keyboard pushbutton 0 and desired waypoint number pushbutton — Depressed.

Note

Verify that from-to display is the two selected waypoints or present

position and waypoint.

4. INSERT pushbutton — Depressed.

The total distance along the flight plan route selected will appear in the left display. The time will appear in the right

display. Time is based on a fixed velocity of 512 knots when groundspeed is less than 100 knots, and is based on

actual groundspeed when speed is greater than 100 knots.

2.21.24.4.22 Altitude Reference Mode Operation

Attitude reference mode operation enables the aircraft to use the INS as a source of pitch, roll, and platform heading

(attitude) data. Attitude reference is selected in flight when the INS is providing attitude data but no navigational data,

as indicated when the WARN annunciator illuminates with the MSU mode selector switch set to NAV, and

extinguishes when the MSU mode selector switch is set to ATT REF.

Note

Switching to ATT REF with the MSU mode selector switch does not affect

the attitude selection made with the attitude select switch(es) on the main

instrument panel, since the same output is available with the MSU mode

selector switch in either NAV or ATT REF.

If the WARN annunciator illuminates:

1. MSU mode selector switch — ATT REF.

If the WARN annunciator remains illuminated, the INS has malfunctioned and is not providing reliable navigational

or attitude data. If the annunciator extinguishes, the INS is providing accurate attitude data but no navigational data.

If the WARN annunciator extinguishes:

2. Verify that the left and right numerical and from-to displays are blank.

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If the WARN annunciator remains illuminated:

CAUTION

Disengage autopilot prior to switching attitude reference with the attitude

select switch(es).

3. Attitude select switches — GYRO ATT.

4. MSU mode selector switch — OFF.

5. NAV SEL switch — As Desired (except INS).

Note

Once the MSU mode selector switch on the LTN-72 INS is placed in ATT

REF, a ground alignment must be performed before normal navigation can

be resumed. An in-flight alignment may be performed for the LN-100 INS.

2.21.24.4.23 Search Mode Operation

Search mode data can be entered and search pattern initiated whenever the system is in NAV mode. Search pattern

designation as well as initiation and termination of search modes are all accomplished through use of the CDU

from-to display. Both systems can be programmed for search patterns and coupled to the autopilot.

In all CDU selector positions except DSR TK STS, the from-to display functions as described previously until a

search mode is initiated, and then displays 77. With the CDU display selector switch in DSR TK STS, the following

search mode information is displayed:

FROM-TO

DESCRIPTION

Search Mode Disabled

Ladder

Sector

Square

Auto Search Start (when to waypoint is reached)

Manual Search Start

Like numbers only can be inserted when the CDU display selector switch is in DSR TK STS. Unlike numbers will

be rejected. Search pattern designation, data entry, search mode initiation, and termination are accomplished as

follows:

1. A search pattern may be designated by depressing the TK CHG pushbutton with the CDU display selector

switchinDSRTKSTSandenteringeither22(ladder),33(sector),or44(square)asdesired.TheCDUfunction

selector switch must be in either AUTO or MAN.

2. Search mode parameters required to define each search pattern may then be entered through the DSR TK STS

left and right displays. Search mode data must be entered and verified on the CDU prior to beginning the

search.

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3. Search mode may then be enabled in one of two ways:

a. Manually — By inserting 66 into the from-to display (with CDU display selector switch set to DSR TK

STS), the search pattern is immediately initiated and present position is used as the datum modem point.

b. Automatically — When 55 is inserted into the from-to display (with CDU display selector switch set to

DSR TK STS), search mode will not be entered until distance to go to the to waypoint reaches 0. At that

time, present position is stored as the datum modem point and the search pattern is initiated.

Note

Manually inserted crosstrack offsets are automatically removed at the time

55 or 66 is entered.

The search pattern (22, 33, or 44) must have been designated before search initiation (55 or 66) can be accomplished.

Once 55 or 66 is entered, it will be displayed in the from-to display (with the CDU display selector switch in DSR

TK STS)for approximately 5 seconds, afterwhich thedisplay will revert back to thesearch pattern being flown. The

from-to display indicates 77 in all CDU display selector switch positions other than DSR TK STS, once a search

pattern has been initiated.

Note

Should the operator wish to recall search mode parameters during search

execution, the CLEAR pushbutton may be pressed on the CDU. With the

CDU display selector switch set to DSR TK STS, search data will be

displayed for approximately 5 seconds. The method of search mode

initiation (55 or 66) will also be displayed for 5 seconds. During search

operation, search mode data cannot be entered or altered.

4. Two steps are required to terminate a search mode:

a. 00 must be entered through the from-to display with the CDU display selector switch set to DSR TK STS.

b. A new track must be established by entering a track change. The CDU display selector switch must be in

a position other than DSR TK STS.

Once a search mode is partially terminated (by entering 00), the TK CHG pushbutton will flash, indicating the need

to establish a new track. Should the operator fail to make a track change before the aircraft reaches the current

waypoint (waypoint 8), the INS will behave as if in the manual mode, regardless of the setting of the CDU function

selector switch. The ALERT light will begin flashing as an indication to change tracks, but the aircraft will continue

on the previously determined track until a track change has been initiated.

Once a 55 or 66 has been entered into the system, the only entry allowed with the CDU function selector switch in

DSR TK STS is 00; anything else will be rejected.

Search Mode Initialization

The operator has the option of initiating a search mode either manually (66) or automatically (55). The procedure

for automatic search initialization with the INS coupled to the autopilot is as follows:

1. Enter the search initialize latitude and longitude position into the CDU as a waypoint.

2. Set the CDU function selector switch to AUTO or MAN.

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3. Select a desired track to the search initialize waypoint (by entering the waypoint used for the search initialize

position as the to waypoint).

4. Two steps are required to terminate a search mode: in DSR TK STS, enter and verify the search mode data

for the desired searchpath.

5. Couple the autopilot to the INS.

6. With the CDU display selector switch set to DSR TK STS, enter 55 into the from-to display. When distance

to go reaches zero, the search pattern will automatically begin.

Note

Should search parameters be entered that would produce nonoptimal

steering(i.e.,excessiveovershooting)theTKCHGandINSERTlightswill

flash at the time the search pattern is initiated. The pattern may be

continued, should the operator desire, with the lights flashing, or search

mode may be terminated and new parameters inserted.

Search Mode Readouts

CDU readouts during search mode operation are as follows:

1. From-to display indicates 77 in all positions of the display selector switch except DSR TK STS.

2. XTK/TKE display values are aircraft position with respect to the searchpath.

3. Waypoints 7, 8, and 9 contain position coordinates of from, to, and next waypoints.

Note

Waypoints 7, 8, and 9 coordinates change as search progresses. During

search mode operation, waypoints 7, 8, and 9 cannot be manually changed.

4. DIS/TIME display values are with respect to the to waypoint (waypoint 8) of the search.

5. Desired track with respect to the searchpath is displayed in the DSR TK STS position.

HSI readouts for the INS being used are as follows:

1. Course arrow with respect to the compass card is the desired track angle of the searchpath.

2. Course arrow with respect to the “T” end of the bearing pointer is the track-angle error of aircraft track with

respect to desired track angle of the searchpath.

3. Coursebarindications display crosstrack distancedeviation from desiredsearchpath (onedot deviationequals

3,000 yards, about 1.5 nm).

4. Compass card with respect to the lubber line is the true heading of the aircraft.

5. The “T” end of the bearing pointer with respect to the compass card is the track angle of the aircraft.

6. The “T” end of the bearing pointer with respect to the lubber line is the drift angle of the aircraft.

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Termination of Search Mode

The following procedure must be used in order to terminate the search mode:

Verify that the coordinates of fly-to waypoint are entered into any numbered waypoint except waypoints 7,

8, or 9.

CDU display selector switch — DSR TK STS.

Keyboard TK CHG pushbutton — Depressed.

Note

Verify that TK CHG and INSERT pushbuttons are illuminated.

In sequence, press 0 pushbutton two times.

Note

Verify that TK CHG pushbutton is now flashing.

CDU display selector switch — Any position except DSR TK STS.

Keyboard TK CHG pushbutton — Depressed.

Note

Verify that TK CHG and INSERT pushbuttons are illuminated.

In sequence, press 0 pushbutton and then waypoint number selected in step 1. Search mode is now terminated.

Note

Termination is required before a new search pattern can be designated.

Search Modes Data Entry and Display

The three search patterns that have been mechanized in the INS are:

1. Ladder (creeping line).

2. Sector.

3. Square (expanding square).

Any one of the three search modes is capable of being programmed into the INS (see Figure 2-130). Search mode

data may be entered and displayed either on the ground or in flight, but only with the MSU mode selector switch

positioned to NAV.

Search mode data must be entered and verified on the CDU prior to beginning the search pattern.

Note

D Recall of the original search mode data may be accomplished by

momentarily depressing the CDU CLEAR pushbutton.

D If less than minimum values of track spacing, radius, or sweep width are

entered into the INS, the CDU TK CHG and INSERT pushbuttons will

flash at the time the search is initiated and erratic track leg switching may

occur during execution of the search pattern.

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Ladder Search Variables

Four variables are required to be inserted into the INS to define the ladder searchpath:

1. Major search axis-angle (0) with respect to true north in degrees and tenths of degrees. Range of variable is

0.0_ to 359.9_.

2. Sweep width (W) in nautical miles. Range of variable is 0.0 to 999.9 nm.

3. Track spacing (S) in nautical miles. Range of variable is 0.0 to 99.9 nm.

4. Direction of first turn: right bank R, left bank L.

Note

Track leg switching will occur prior to each waypoint. Switching time is

variable, depending on groundspeed.

Ladder Search Data Entry and Display

The ladder search data for the following example is major search axis (0) of 310.1_, a sweep width (W) of 40.0

nm,

a track spacing (S) of 10.0 nm, and the first turn to the left. Enter the ladder search data as follows:

CDU function selector switch — MAN or AUTO.

CDU display selector switch — DSR TK STS.

Note

Verify that from-to display shows 00.

Keyboard TK CHG pushbutton — Depressed.

Keyboard pushbuttons — Depressed.

Note

Depress keyboard pushbutton 2, two times.

Keyboard INSERT pushbutton — Depressed.

Note

Verify that four zeros appear in both the left and right displays.

Keyboard pushbutton L — Depressed.

Note

Verify that left display blanks and INSERT pushbutton illuminates.

In sequence, press 3, 1, 0, and 0 keyboard pushbuttons — Depressed.

Note

Verify that the left display is the major search axis angle entered.

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INSERT pushbutton — Depressed.

Keyboard pushbutton R — Depressed.

Note

Verify that right display blanks and INSERT pushbutton illuminates.

10.

In sequence, press 4, 0, and 0 keyboard push-buttons — Depressed.

Note

Verify that the right display is the sweep width entered.

11.

INSERT pushbutton — Depressed.

12.

CDU function selector switch — RMT.

13.

Keyboard pushbutton L — Depressed.

Note

LispressedforthefirstturnleftdirectionandRispressed forfirst turnright

direction. Also verify that INSERT pushbutton is on.

14.

In sequence, press 1, 0, and 0 keyboard pushbuttons — Depressed.

Note

Verify that first turn direction and track spacing are correct on the display.

15.

INSERT pushbutton — Depressed.

Note

CDU TK CHG and INSERT pushbuttons will flash if less than minimum

values have been entered for search pattern track legs.

Sector Search Variables

Three variables are required to be inserted into the INS to define the sector searchpath:

Note

All turns are right bank.

1. Radius(R) in nautical miles; range of variable is 0 to 99 nm.

2. Leg separation angle (0₂) in degrees and tenths of a degree; range of variable is 0.0_ to 99.9_. 10_ minimum

0₂ is recommended for groundspeeds above 140 knots.

3. Initial desired track angle (0₁) with respect to true north in degrees and tenths of a degree. Range of variable

is 0.0_ to 359.9_.

Note

Track leg switching will occur prior to each waypoint. Switching time is

a variable as a function of groundspeed.

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Sector Search Data Entry and Display

The sector search data for the following example with an initial desired track angle (0₁) of 33_, a search radius (R)

of 10 nm, and a leg separation angle(0₂) of30.0_. Forsector search patterns, all turns areright bank. Enter thesector

search data as follows:

CDU function selector switch — MAN or AUTO.

CDU display sector switch — DSR TK STS.

Note

Verify that from-to display shows 00.

Keyboard TK CHG pushbutton — Depressed.

Keyboard pushbuttons — Depressed.

Note

Depress keyboard pushbutton 3, two times.

Keyboard INSERT pushbutton — Depressed.

Note

Verify that four zeroes appear in the left display and that five zeroes appear

in the right display.

Keyboard pushbutton L — Depressed.

Note

Verify that left display blanks and INSERT pushbutton illuminates.

In sequence, press 3, 3, 0, and 0 keyboard pushbuttons — Depressed.

Note

Verify that the left display is the initial desired track angle entered.

Keyboard INSERT pushbutton — Depressed.

Keyboard pushbutton R — Depressed.

Note

Verify that right display blanks and INSERT pushbutton illuminates.

10.

In sequence, press 1, 0, and then 3, 0, and 0 keyboard pushbuttons — Depressed.

Note

Verify that the right display shows the search radius and leg separation

entered.

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11. INSERT keyboard pushbutton — Depressed.

Expanding Square Search Variables

Two variables are required to be inserted into the INS to define the expanding square searchpath:

Note

All turns are right bank.

1. Sweep width (S) in tenths of a nautical mile; range of variable is 0.0 to 99.9 nm.

2. Initial desired track angle (0) with respect to true north in degrees and tenths of a degree; range of variable is

0.0_ to 359.9_.

Expanding Square Data Entry and Display

The expanding square data for the following example is with an initial desired track angle (0) of 315.0_ and sweep

width (S) of 15.0 nm. For the expanding square search pattern, all turns are right bank.

Enter expanding square search data as follows:

CDU function selector switch — MAN or AUTO.

CDU display selector switch — DSR TK STS.

Note

Verify that from-to display shows 00.

Keyboard INSERT pushbutton — Depressed.

Keyboard pushbuttons — Depressed.

Note

Depress keyboard pushbutton 4, two times.

Keyboard INSERT pushbutton — Depressed.

Note

Verify that four zeroes appear in the left display and three zeroes appear in

the right display.

Keyboard L pushbutton — Depressed.

Note

Verify that left display blanks and INSERT pushbutton illuminates.

In sequence, press 3, 1, 5, and 0 pushbuttons — Depressed.

Note

Verify that the left display is the initial desired track angle entered.

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8. Keyboard INSERT pushbutton — Depressed.

9. Keyboard pushbutton R — Depressed.

Note

Verify that right display blanks and INSERT pushbutton illuminates.

10. In sequence, press 1, 5, and 0 pushbuttons — Depressed.

Note

Verify that the right display is the sweep width entered.

11. Keyboard INSERT pushbutton — Depressed.

2.21.24.4.24 After Landing Operations

Navigation Accuracy Check. The accuracy of the INS should be determined at the end of each INS flight prior to

system shutdown. The check should be made when the aircraft is parked at a known location.

Check the INS accuracy as follows:

1. Using Update Removal or Position Update Check procedure, remove all position updates.

2. Verify correct parking position coordinates and enter as a waypoint.

3. CDU function selector switch — AUTO or MAN.

4. Enter TK CHG from present position (0) to parking position waypoint.

5. CDU display selector switch — DIS/TIME.

6. System error in nm/hr — Computed.

Divide distance display by the number of hours and tenths of an hour of flight time in the navigation mode.

In-Transit Stops

The system should be left in the navigation mode of operation during short in-transit stops when the navigation

accuracy does not require improvement.

INS Shutdown

The system is shut down by pulling and rotating the MSU mode selector switch to the OFF position.

2.21.25 LTN-211 Omega Navigation System

Note

As of 1 October 1997, ONS is inoperative because of decommissioning of

Omega stations worldwide.

2.21.26 True Airspeed Computer

The TAS computer provides TAS input to the No. 1, No. 2, or No. 3 INS. True airspeed is displayed on the TAS

indicator on the navigator instrument panel (see Figure 2-131). The TAS computer and a transducer are mounted on

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the right-hand underdeck rack (see Figure 2-84). Ram air pressure and atmospheric pressure to operate the TAS

computer is provided by the pitot-static system (see Figure 2-80). Outside air temperature is provided from a total

temperature probe installed on the left side of the aircraft above the crew entrance door. The TAS computer uses

26-Vac power from the essential ac bus through the TAS circuit breaker on the pilot upper circuit breaker panel. The

TAS computer also uses 28-Vdc power from the essential dc bus through the TAS circuit breaker on the copilot upper

circuit breaker panel.

2.21.26.1 True Airspeed Computer Indicator

Thetrueairspeedcomputerindicatorismountedonthenavigatorinstrumentpanel (seeFigure2-131).Therearethree

pushbutton switches on the front of the indicator. Each switch is momentary and will continuously advance the

operation until released. One pushbutton is for changing modes. One pushbutton is for starting, stopping, and

resetting the timer. The other pushbutton is used to control the brightness of the display and for lamp test. Legends

are backlighted for indicating the display operating mode and _C or knots.

To test the true airspeed computer indicator lights, depress the MODE and dim/off buttons simultaneously. Assure

that the three displays indicate 8 and that the mode indicators, the colon, Kts, and _C annunciators flash.

2.21.27 AN/APS-133(M) Multimode Radar Set

The AN/APS-133(M) multimode color radar set consists of the following components: an antenna, a

receiver-transmitter, a pilot and navigator indicator, an interface unit, a radar control panel, a display control unit,

and a sector scan control panel (see Figure 2-132). The radar set operates on 28-Vdc power from the main dc bus and

115-volt primary ac power from the essential ac bus on aircraft prior to 165313 and from the essential avionics bus

on aircraft 165313 and up through the RADAR circuit breakers on the copilot upper circuit breaker panel.

Figure 2-131. True Airspeed Computer Indicator

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Figure 2-132. AN/APS-133(M) Multimode Radar Indicator Control Panels (Sheet 1 of 2)

The multimode radar features include weather avoidance, long-range beacon homing incorporating marker and delay

modes,groundandair-to-airmappingcapability,IFFdisplay,INSwaypointandcourselineoverlays,refuelingoffset

line, and target marker providing either LAT/LONG coordinates or range/bearing data.

As a weather avoidance radar, the set detects and displays precipitation areas in red, yellow, and green. The red areas

indicate heaviest precipitation or storm centers, yellow indicates lower precipitation rates, and green indicates lightest

rainfall. Azimuth lines, fixed range marks, and alphanumerics are displayed in blue. Automatic penetration circuits

prevent storm areas at close range from masking other storm areas at the same azimuth but longer range.

As a terrain mapping radar, the set scans a selected range of Earth and provides a display of prominent topographical

features such as lakes, rivers, islands, high ground, bridges, cities, etc. These features are presented on the indicator

in adisplay resembling an ordinary pilotagechart. Thedetected terrain features are displayed in red, yellow, and blue

according to the strength of the target returns: red for strongest returns, yellow for medium, and blue for lowest.

Azimuth lines, range marks, and alphanumerics are displayed in green.

In the air-to-air mapping function, the set presents a display of other aircraft in the immediate vicinity of the present

flightpath. Detected aircraft are displayed in red, yellow, or blue: red for strongest returns, yellow for medium level,

and blue for lowest level. Azimuth lines, fixed-range marks, and alphanumerics are displayed in green. The effective

range in this function is limited by the size of the target aircraft, but detection of a large aircraft such as a C-130 could

be expected at 10 nm.

As a beacon navigation radar, the set transmits an interrogation signal to trigger an X-band beacon. Operating beacons

within range transmit a response pulse that is received by the radar set and displayed as an arc on the indicator at the

relative bearing and distance to the beacon. The beacon response is displayed in green only. Azimuth lines, range

marks, and internally generated alphanumerics are displayed in blue.

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IFF codes from cooperating aircraft (green lines) can be displayed along with LAT/LONG or range/bearing when

the target marker feature is used. Azimuth lines, range marks, and internally generated alpha-numerics are displayed

in blue.

INS waypoints and connecting course lines can be displayed in addition to IFF codes from cooperating aircraft.

Azimuth lines, range marks, and internally generated alphanumerics are displayed in blue.

2.21.27.1 Controls and Indicators

The radar set operating controls and indicators are contained on the radar indicators and the following panels:

1. At the navigator station — Radar control panel, display control unit, sector scan control panel, and

pilot/navigator radar control indicator.

2. At the pilot side panel — Pilot/navigator radar select and annunciator panel, radar control panel, and radar

switch panel.

2.21.27.1.1 Radar Indicators

The radar indicators contain the following controls for radar indicator presentation.

Range Selector

The range selector selects the range in nautical miles displayed on the radar indicator and the distance between

fixed-range markers: 5 nm with 1-nm range markers; 10 nm with 2-nm range markers; 15 nm with 3-nm range

markers; 25 nm with 5-nm range markers; 50 nm with 10-nm range markers; 150 nm with 30-nm range markers; or

300 nm with 60-nm range markers. The selected range/range-marker combination is displayed in the upper right

corner of the radar indicator scope.

HOLD Pushbutton

The HOLD pushbutton allows the operator to freeze the display. When HOLD is pressed in, the present display on

the radar indicator is retained instead of being updated by subsequent azimuth scans. The notation HOLD flashes

alternately with the function (WX, BCN, etc.) in the upper left corner of the radar indicator scope. Pressing HOLD

again or changing range selector position resumes normal updating of the display.

TGT CLAR Control

TheTGTCLARcontroladjuststhreshold forfirst-level radarreturns (greendatainWX andBCN, bluedatainMAP1

and MAP2) and allows reduction of extraneous backg0round noise.

INT Control

The INT control adjusts brightness (intensity) of presentation on the radar indicator for best signal visibility and

contrast, and also contains the OFF switch for the indicator.

NOR-MKR-DLY Switch

The NOR-MKR-DLY switch selects the video presentation mode. In NOR, the normal video display is presented

with zero range at the bottom center of the scope. In MARK, a yellow variable range marker is added. The position

(range) of the variable marker is controlled by the SLEW control and is displayed in the upper right corner of the radar

indicator. In DLY, the range sweep starts at the variable range marker setting, as displayed in the upper right of the

indicator. The full range (with fixed-range marks) selected by the range selector switch on the indicator is displayed.

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Thenotation DLYis displayedin theupperleftoftheradarindicatorand theminimum rangeis displayedin theupper

right. For example, if the range scale selected is 50/10 and the variable marker is set at 100 nm, only the range from

100 nm to 150 nm would be displayed, with 100 nm at the bottom center of the indicator and the legends DLY and

100 would be displayed in the upper left and upper right, respectively.

2.21.27.1.2 Radar Control Panel

The radar control panel contains the following controls for the multimode radar set.

Function Selector Switch

The function selector is a seven-position, pull-and-turn action switch. In OFF, all power is removed from the radar

set. In STBY, a 3-minute warmup time delay is activated. In TEST, the radar set radiates into a dummy load, a test

pattern is displayed on the radar indicator (if 3-minute delay from OFF has expired), and the system executes an

internal test sequence. TheANT and/orRTfault indicatorsmay lightto signaldetected faults.In WX,thesetdisplays

weather detection information and the antenna radiates a narrow pencil beam. MAP1 and MAP2 are used for terrain

mapping. The antenna beam pattern is selectable by the PENCIL/FAN switch. The MAP2 position is recommended

for low-level mapping and for short-range, air-to-air operation. In BCN, bearing and distance information relative

to responding beacon stations is displayed. In all positions except OFF and STBY the selected function is displayed

on the upper left of the radar indicator scope.

PENCIL-FAN Switch

The PENCIL-FAN switch is enabled only in the MAP1 and MAP2 functions. When enabled, it selects the radiated

beam shape. The pencil beam is a narrow, symmetrical beam approximately 3_ in elevation and azimuth. The fan

beam is broadened in the elevation plane.

LONG-SHORT Switch

The LONG-SHORT switch selects long (5.0 microseconds) or short (0.4 microsecond) pulse while in map modes.

ANT TILT Control

The ANT TILT control selects the tilt of the azimuth scan plane from +14_ to -14_ in relation to the selected 0_ plane

selected by the ANT STAB switch.

ANT STAB Switch

The ANT STAB switch enables or disables antenna stabilization. In ON, the antenna is roll and pitch stabilized within

limits throughout azimuth scan so that 0_ tilt is the true horizontal plane. In OFF, the 0_ antenna tilt is the present

plane of the aircraft.

CAUTION

The ANT STAB switch should be in ON during all normal operation of the

AN/APS-133(M). It may be turned to OFF if antenna stabilization fails

during flight.

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C-130T. FLIGHT MANUAL (2006) - page 6