TECHNICAL MANUAL MAINTENANCE MANUAL FOR ARMY CH-47D HELICOPTER (1992)

TM 55-1520-240-10

MODE SELECTOR - UTM.

d. Press keys 1, 3, and 1. Left display indicates 131.

Press KYBD pushbutton, control shifts to right display,

b. DISPLAY selector - DEST-TGT.

and right display blanks. Press keys 0, 2 and 4.)

c. DEST DISP thumbwheel - P, numeral, or H as

e. ENT key -

Press. The entire display will blank,

desired.

and TGT STR number will reappear. Display should

d. Present position and destination - Enter. (Exam-

indicate

131

024°.

ple: Entry of zone 31T, area CF, casting 0958 and

northing

3849).

3-43. System Initialization.

(1) KYBD pushbutton

- Press. Observe that dis-

a. DEST DISP thumbwheel - P.

play freeze and TGT STR indicator blanks.

b. Present position spheroid and/or variation (para.

(2) KYBD pushbutton - Press. Observe that

3-39)

- Enter.

center display blanks.

NOTE

(3) Key 3, 1, 7, and 8 - Press.

Do not press ENT key after entering initial

(4) KYBD button -

Press. Observe left and right

position fix.

displays blank.

(5) Key 1, 3, 2, 3, 0, 9, 5, 8, 3, 8, 4, 9 - Press.

c. Initial fix position (para. 3-40 or 3-41) - Enter.

(6) ENT key -

Press. Left, right and center dis-

d. When the helicopter is sitting over or overflies the

plays will momentarily blank and then display CF 0958,

initial fix position - ENT..

3849, 31T, respectively. TGT STR number will appear.

e. FLY-TO DEST thumbwheel - Set to desired des-

3-41. Entering Present Position or Destination in

tination. The computer calculates a course between the

LAT/LONG.

destination and the helicopter position at the time the

The variation of a destination must be entered after the

destination was selected.

associated destination coordinates are entered, since

each time a destination is entered its associated varia-

3-44. Flight Procedures.

tion is deleted. The order of entry for present position is

irrelevant.

3-45. Update of Present Position from Stored

Destination.

a. MODE selector - LAT/LONG.

b. DISPLAY selector - DEST-TGT.

a. FLY-TO DEST thumbwheel - Set to destination

to be overflown.

c. DEST DISP thumbwheel - P, numeral, or H as

desired.

b. DISPLAY selector - DIST/BRG-TIME.

d. Present position or destination - Enter. (Exam-

c. KYBD pushbutton -

Press and release when he-

ple: Entry of N41° 10.1 minutes and E035° 50.2 min-

licopter is over the destination. Display freezes upon

utes.)

release of the pushbutton.

(1) KYBD pushbutton - Press. Observe that dis-

NOTE

play freezes and TGT STR indicator blanks.

If a present position update is not desired, as

(2) KYBD pushbutton

- Press. Observe that left

indicated by an appropriately small value of

display blanks.

distance to go on overflying the destination,

(3) Key 5, 5, 4.1, 1, 0, and 1 - Press.

set the DISPLAY selector to some other

position; this aborts the update mode.

(4) KYBD pushbutton - Press. Observe right

display blank.

(5) Key 2, 2, 0, 3, 5, 5, 0, and 2- Press.

d, ENT key - Press if update is required.

(6) ENT key - Press. Left, right, and center

3-46. Update of Present Position from Landmark.

displays will momentarily blank and TGT STR number

will reappear. Displays should indicate N41° 10.1 E 035°

There are two methods for updating from a landmark.

50.2.

Method 1 is useful if the landmark comes up unexpect-

edly and the operator needs time to determine the

3-42. Entering Ground Speed and Track.

coordinates. Method 2 is used when the landmark

a. MODE selector - BACK UP.

update is anticipated.

b. DISPLAY selector - GS-TK.

a. Method 1.

c. Ground speed and track - Enter. (Example; En-

(1) DISPLAY selector - PP.

ter 131 km/h and 024°. Press KYBD pushbutton, ob-

serve that left display freezes and TGT STR indicator

(2) KYBD pushbutton - Press as landmark is

blanks. Press KYBD pushbutton and observe that left

overflown. Present position display will freeze upon

display blanks.

release of pushbutton.

3-27

TM 55-1520-240-10

(3) Compare landmark coordinates with those on

b. DISPLAY selector - XTK/TKE.

display.

c. Fly to keep the left display at L or R 000.0 and the

right display to L or R 000.

NOTE

If present position update is not desired, as

3-49. Target Store (TGT STR) Operation.

indicated by a small difference between the

Two methods may be used for target store operation.

displayed coordinates and the landmark co-

Method 1 is normally used when time is not available for

ordinates, set the DISPLAY selector to some

preplanning a target store operation. Method 2 is used

other position; this aborts the update.

when time is available and it is desired to store a target

in a specific DEST DISP position.

(4) Landmark coordinates - Enter if difference

a. Method 1.

warrants an update.

(1) TGT STR pushbutton - Press when flying

(5) ENT key -

Press if update is required.

over target.

b. Method 2.

(2) Present position at the time the pushbutton is

(1) DISPLAY selector - DEST/TGT.

released is automatically stored and the destination

(2) DEST DISP thumbwheel - P. Present posi-

location is that which was displayed in the target store

tion coordinates should be displayed.

indicator (position

8 or 9) immediately before

pressing the TGT STR pushbutton.

(3) KYBD pushbutton

- Press, observe that dis-

play freezes.

b. Method 2,

(1) MODE selector -

UTM or LAT/LONG, de-

NOTE

pending on coordinate format desired.

If present position update is not desired, as

(2)

DISPLAY selector - DEST/TGT.

indicated by a small difference between the

displayed coordinates and the landmark co-

(3)

DEST DISP thumbwheel - P.

ordinates, set the DISPLAY selector to some

(4)

KYBD pushbutton -

Press when over flying

other position; this aborts the update.

potential

target, Display should freeze.

(4) Landmark coordinates - Manually enter via

NOTE

keyboard.

Do not press ENT key while DEST DISP

thumbwheel is at P.

(5) ENT key - Press when overflying landmark.

3-47. FLY-TO-DEST Operation.

(5) If it is desired to store the target, turn DEST

a. When the FLY-TO-DEST thumbwheel is selected

DISP thumbwheel to destination location desired and

to a new position, the helicopter’s present position at

press ENT key.

the time is stored in the computer. A course is then

(6) If it is not desired to store the target, place

computed from the helicopter’s present position, as

DISPLAY selector momentarily to another position.

stored, to the destination selected. If the helicopter

deviates from this course, crosstrack error (XTK) is

3-50. Transferring Stored Target Coordinates

computed.

from One Location to Another.

b. Range and bearing to destination, current track

The following procedure allows the operator to transfer

made good, and track angle error (TKE) correction are

stored target coordinates from one thumbwheel loca-

computed from the helicopter’s present position to

tion to another. For example, it is assumed that the pilot

selected destination.

wants to put the coordinates of stored target 7 into

location of destination 2.

3-48. Left-Right Steering Signals.

Flying the shortest distance to the destination from

NOTE

present position:

Throughout this procedure, range, time-to-

a. FLY-TO DEST thumbwheel - Select desired des-

go, bearing and left/right steering data are

tination.

computed and displayed for the destination

selected via the FLY-TO DEST thumbwheel.

NOTE

If the desired destination is already selected

DISPLAY selector - DEST/TGT.

but an updated course is needed, then the

FLY-TO DEST thumbwheel must be cycled

DEST DISP thumbwheel - 7.

to another destination and back so the com-

KYBD pushbutton - Press,

puter will recalculate the new course.

d. DEST DISP thumbwheel - 2.

3-28

TM 55-1520-240-10

e. ENT key - Press.

through the HSI MODE SELECT panel on each

instrument panel below each HSI. Each HSI receives

3-51.

Transferring Variation from One Location to

electrical power from three different sources (copilots

Another.

sources are in parentheses): 28 volt DC from the No. 2

The procedure to transfer variation data to the same

(No. 1) DC bus through the NAV PLT (COPLT) HSI

location where the associated stored target coordinates

MODE SEL circuit breaker, 115 volt AC from the No. 2

has been transferred is the same as in previous

(No. 1) AC bus through the NAV PLT (COPLT) HSI

paragraph. Transferring Stored Target Coordinates from

circuit breaker, and 26 volt AC from the No. 2 (No. 1)

One Location to Another, except that the DISPLAY

instrument bus through the NAV PLT (COPLT) HSI

selector is placed at SPH/VAR.

circuit breaker.

3-52.

Dead Reckoning Navigation.

3-56.

Controls and Indicators - Horizontal Situation

As a BACKUP mode, dead reckoning navigation can be

Indicators. (fig. 3-14)

done using ground speed and track angle estimates

provided by the operator.

CONTROLS/

INDICATOR

FUNCTION

a. MODE selector - BACKUP.

b. DISPLAY selector - GS/TK.

Compass Card

The compass card is a 360° scale

c. Best estimate of ground speed and track angle -

that turns to display heading data

Enter via keyboard.

obtained from the gyro magnetic

d. Set MODE selector to any other position to abort

compass (AN/ASN43A. .The

this mode.

helicopter headings are read at the

upper lubber line.

3-53.

Operation During and After Power

Interruption.

Bearing Pointer No.1 The pointer operates in conjunction

During a DC power interruption inflight, or when all

with

doppler

mixed

helicopter power is removed, the random access

GPS/Doppler. With Doppler Only,

memory (RAM) (stored destination and present position)

indicates magnetic bearing to

data is retained by power from an 8.4 volt DC dry cell

doppler destination. With mixed

battery. This makes it unnecessary to reenter any

GPS/Doppler, indicates magnetic

navigational data when power returns or before each

bearing to GPS destination. (With

flight. If the battery does not retain the stored destination

GPS Only, bearing information is

data during power interruption, the display will indicate an

not available.

EN when power returns. This indicates to the pilot that

previously stored data has been lost, and that present

Bearing Pointer No.2 The pointer operates in conjunction

position, spheroid/variation, and destinations must be

with selected VOR or ADF receiver.

entered. The computer, upon return of power, resets

The pointer is read against the

present position variation to E000.0, destination and

compass card and indicates the

associated variations to a non-entered state, sets wind to

magnetic bearing to the VOR or

zero and spheroid to CL6.The following data must be

ADF station.

entered following battery failure:

Course Deviation Indi-This indicator indicates This

a. Spheroid.

cator

indicator indicates lateral deviation

b. Present position variation.

from a selected VOR course or

c. Present position.

GPS/Doppler computed course or

d. Each destination and its associated variation.

heading in the case of FM homing.

When the helicopter is flying to

3-54.

Stopping Procedure.

correct

course,

the

course

indicator will be aligned with the

MODE selector - OFF.

course pointer and will be centered

on the fixed aircraft symbol. The

3-55.

Horizontal Situation Indicator (HSI).

two dots on either side of the

Two horizontal situation indicators (HSI) (fig. 3-14), one

indicator indicate amount of course

on each pilot’s instrument panel, are installed. Each

deviation. One dot displacement is

indicator can display helicopter heading, FM homing, and

equivalent to

5 off VOR or

position relative to a selected course or bearing. Also,

GPS/Doppler and 11/4 degree 1 off

during an ILS approach, the indicator displays helicopter

localizer

course.

These

position relative to the glide slope and localizer. The

displacements do not apply to FM

automatic heading select feature of the AFCS is also

homing.

controlled through the HSI. Selection of navigational

equipment to be displayed on each HSI is controlled

Change 6 3-29

TM 55-1520-240-10

CONTROLS/

INDICATOR

FUNCTION

INDICATOR

FUNCTION

CRS Knob

The COURSE indicator and course

Glide Slope (GS)

Indicates loss of or an unreliable

Course Indicator

pointer operate in conjunction with

Warning Flag

glide slope or FM homing signal.

Course Pointer

the course select (CRS) knob, and

allow the pilot to select any VOR

357.

Horizontal Situation Indicator Mode Select

course. The course pointer turns

Panel. (fig. 3-14) The HSI MODE SELECT panel is on

with the compass card and will he

each pilots instrument panel below the HSI. The panel

aligned with the lubber line when the

allows the pilot to select the navigation mode to be

helicopter heading is the same as

displayed on the HSI, command AFCS heading select

the selected course.

feature, and visually indicates marker beacon passage.

The panel is divided into three sections labeled CRS,

Range Indicator

Digital distance display in kilometers

BRG, and MKR BCN.

(KM) to destination set on GPS

Control Display Unit (CDU) (para.

a. The CRS (course) section consists of four

3-67) or doppler control FLYTODEST

pushbutton selector switches labeled VOR SEL,

thumbwheel (para. 3-34).

GPS/DOP SEL, FM I SEL, and CMDSEL.

Pressing

VOR SEL, GPS/DOP SEL, or FMSEL causes the output

HDG Knob

Heading select (HDG)

knob

of the selected navigation set to be electrically connected

operates in conjunction with the

to the course deviation indicator on the corresponding

heading bug. It allows the pilot to

HSI and lights SEL legend in the switch. These switches

select any one heading. With CMD

are electrically interlocked so only one set may be

SEL (fig.

3-14) selected on the HSI

selected at a time. Selecting another navigational

MODE SELECT panel, the AFCS

modes, automatically disengages the mode in use, turns

(chapter 2) will turn the helicopter to

out the SEL legend of the mode in use, engages the

and maintain the selected heading.

selected mode, and lights the SEL legend of the selected

mode. Each pilot may independently select different

HDG Flag

The HDG flag is in view when the

navigational modes for display on his HSI.

signal from the gyro magnetic

compass is unreliable or power to

b. Pressing CMD SEL engages the AFCS heading

the indicator is lost.

select feature, causes the helicopter to turn to and

maintain heading to which the HSI heading bug is set,

To-From Arrow

To from arrow indicates that the

and illuminates the SEL legend on the switch. Due to

helicopter is flying to or away from a

electrical interlocks between the two HSI control panels,

selected VOR.

both CMD SEL switches cannot be engaged at the same

time. The engaged switch is indicated by the lit SEL

NAV Flag

The NAV flag turns with the

legend. If the opposite CMD SEL switch is pressed

compass card. The flag will retract

when operating with heading select, the HDG on the

from view when a reliable VOR,

AFCS panel will release and heading select will be

GPS/Doppler or FM homing signal is

disengaged. Control of the course deviation indicator in

being applied to the instrument.

the VOR mode relative to bearing and course deviation

to or from a VOR is assigned to the pilot who has CMD

Aircraft Symbol

Corresponds to longitudinal axis of

SEL engaged. If the pilot who does not have CMD SEL

the helicopter; shows helicopter

engaged makes an adjustment on his CRS knob, it will

position and heading relative to the

have no effect on the CDI relative to the course.

selected course.

c. Pressing VOR/ADF pushbutton on the BRG side

Glide Slope Pointer Displays glide slope position relative

selects the navigational aid, the bearing of which will be

to the helicopter or FM homing

indicated by the HSI No. 2 pointer. The switch is divided

signal strength. When pointer is

into two segments labeled VOR and ADF. If the VOR

above center, helicopter is below

segment is lit, the No. 2 pointer will indicate the bearing

glide slope, conversely when pointer

to a VOR station to which the VHF navigation set is

is below center, helicopter is above

tuned. Pressing the switch will cause the VOR segment

glide slope.

Increasing homing

to go out and the No. 2 pointer will indicate the bearing to

signal strength is shown by pointer

the station to which the ADF set is tuned out and light the

rising. Decreasing signal strength

ADF segment. The opposite action occurs if the ADF

is shown by pointer falling.

segment is lit and the switch is pressed.

Change 6 3-31

TM 55-1520-240-10

d. A MKR BCN light will illuminate during marker

entry. The CLR key clears the data entry field, the ENT

beacon passage. The light labeled O comes on when

key enters data after it has been selected. The ALP key

passing through an outer marker beam. The light la-

allows for mode switching between alpha and numeric

beled M comes on when passing through a middle

data in fields where both need to be entered.

marker and finally the light labeled I comes on when

passing through an inner marker. As each light illumi-

3-61. Controls and Function, Omega Control Unit.

nates, a distinctive tone identifying the beacon will be

(fig. 3-15)

heard over the interphone (table 3-2). The lights have a

press-to-test feature; pressing any one of the three

CONTROLS/

lamps will cause all MKR BCN lamps to illuminate on

INDICATOR

FUNCTION

both pilots HSI MODE SELECT panels.

BRT/DIM

Controls intensity of dis-

3-58. Omega Navigation System (AN/ARN-148).

play.

The AN/ARN-148 is a global navigation system provid-

CLR

Calls up a cursor for data

ing the crew with actual position, distance, bearing and

modification or cancels an

receiver signal strength from Omega station(s). The

operation.

system is comprised of a control display unit (CDU), a

ALP

Shifts keyboard from nu-

navigation processor unit (NW), an airspeed processor,

meric to alpha and back

and an antenna coupler. The airspeed processor takes

to numeric.

airspeed data from the helicopter pitot system for

ENT

Enters selected data into

calculations. Heading information is accessed from the

navigation processing unit

gyro compass system. A zero velocity signal that locks-

memory.

out the system is provided from the aft landing gear

proximity switch when the helicopter is on the ground.

NAV

Provides access to four

The system also features the capability of storing up to

pages of display relative

six pages of flight plans for easy reference.

to aircraft position and

track leg data. Selected

3-59. Omega Navigation Principles.

data pertinent to aircraft

The Omega navigation system (ONS) uses a global

position and track leg

network of eight Omega transmitting stations to provide

data may be altered

dead reckoning coordinates to position the helicopter

through these pages.

relative to one or more transmitting stations. Each

FPL

Provides display, assem-

Omega station transmits a very low frequency (VLF)

bly, selection, entry and

signal continuously.

modification of flight

The Omega VLF signals are received as phase (a

plan.

measure of range to the station) and amplitude (signal

LEG

Provides display and se-

strength). The ONS automatically selects an appropri-

lection from waypoint and

ate set of Omega signals, based on signal strength and

to a waypoint. Provides

geometry, and computes present position and all other

for display and selection

navigation parameters.

of track change mode.

Provides a means of flying

3-60. Omega Control Display Unit.

from present position di-

The CDU is mounted in the center console. The CDU

rect to a defined way-

functions as the primary input and output of navigation

point.

information for the operator (fig. 3-15). This data

Provides a means of dis-

defines helicopter position and navigational guidance

playing additional data

according to a selected path across the ground.

when more than 8 lines of

The CDU has a dual function. The display function is

data are available.

handled by a two inch by three inch color cathode ray

HLD

Provides a means of man-

tube (CRT). The CRT displays information in seven

ually updating position

different colors which uniquely communicates different

either by entering lat/long

information in different colors to the operator. The

coordinates or by refer-

second function of the CDU allows the operator to

ence to point which has

input data into the system to define helicopter position

already been defined to

along the desired navigational path, The data is entered

the Omega Navigation

through a keyboard consisting of 33 keys, Two of the

System (ONS).

keys are used to select the display brightness and one

key is used to turn the system on and off. The remaining

30 keys are used for alpha-numeric data input.

The alphabet is uniquely laid out so that there are no

multi-key-stroke requirements for alpha information

3-32

55-1520-240-10

CONTROLS

CONTROLS/

INDICATOR

FUNCTION

INDICATOR

FUNCTION

EDT

During data entry mode,

The “O” (alpha) key pro-

provides a back space

vides for operator deselec-

function. During non-data

tion of an Omega or VLF

entry mode, provides the

station when the cursor is

capability to change dis-

positioned on the same

play mode of angular

line as the station to be

data, i.e., magnetic, true,

deselected.

grid, heading, bearing,

DTK.

Identifies and permits en-

try of waypoints as a

range and bearing from a

previously entered way-

point.

DAT

Provides six pages for the

selection, display, and en-

try of data related to

flight planning and

Omega/VLF status.

MSG

Provides a display of sys-

tem malfunctions and op

erator actions required.

Displays condition of

ONS data base and allows

selection of various test

modes to ensure correct

system operation.

The “E” or “5” key pro-

vides a means of activat-

ing the erase function

Figure, 3-15.

AN/ARN-148 Omega Control

when the cursor is dis-

Display Unit

played at the top of the

flight plan page.

The “I” or “9” key pro-

vides a means of reversing

the flight plan when the

cursor is displayed at the

top of the flight plan

page.

The "S” or

key pro-

vides a means of selecting

the flight plan for use

when the cursor is dis-

played at the top of the

flight plan page.

55-1520-240-10

3-61.1Doppler/GPS Navigation Set

CONTROL/

FUNCTION

AN/ASN-128B (DGNS).

INDICATOR

The AN/ASN-128B DGNS is an AN/ASN-128 LDNS wMGRS

Selects Military Grid-Referen

an embedded GPS receiver. The AN/ASN-128B in

Systems (MGRS) navigational

conjunction with the aircraft’s heading, vertical refermode of operation.

and position and velocity updates from its internal GPS,

provides accurate aircraft velocity, positioLAT/LONGeeSele

cts latitude/longitude na

information from ground level to 10,000 feet. The systga

tional mode of operation.

provides world-wide navigation, with position readout

available in both Military Grid Reference SyGPSm (MGRS)

Places navigation set in GP

and Latitude and Longitude (LAT/LONG) cooLDGates.

landing mode of operation. Th

Navigation and steering is performed using LAT/LONG

mode provides real-time, tactic

coordinates and a bilateral MGRS-LAT/LONG conversion

precisi

landingguidance

routine is provided for MGRS operation. Up to 100

information to the HSI indica

destinations may be entered in either format and not

necessarily the same format.

DISPLAY switch

Selects navigation data for displ

3-61.2.

Controls, Displays and Function.

WIND-UTC

Used for wind speed and direc

DATA

tion, UTC tim

current,

The control and displays for the AN/ASN-128B are on the

surface wind, GPS status and

front panel (figure 3.15.1). The function of each control is as

data load functions.

follows:

XTK/TKE

Displays steering (cross tra

NOTE

KEY

distance and track angle erro

The MODE switch is locked in the OFF position

information and GPS variabl

and must be pulled out and turned to get into or out

key status. Selection of fl

of OFF position.

destination by direct entry of

digit destination number.

CONTROL/

FUNCTION

INDICATOR

GS/TK

Displays ground speed, trac

NAV M

angle and selection of GPS an

MODE switch

Selects navigation set mode of

navigation mode.

operation.

Displayspresentposition,

OFF

in this position the navigatioPPet

altitude and magnetic variatio

is inoperable; non-volatile RAM

retains stored data.

DIST BRG

Displays distance, bearing an

LAMP TEST

Checks operation of all lamps.TIME

time information

destination or course selecte

TEST

Initiates built-in-self-test exer-

Selection of fly to destination

cise for the Doppler and GPS

be accomplished by direct ent

functions of the navigation set.

of two digit destination numb

3-34 Change

55-1520-240-10

CONTROL/

FUNCTION

CONTROL/

FUNCTION

INDICATOR

Keyboard and LTRUsed to set up data for entry

Keys

memory. When DISPLAY

Accesses way point or target data

switch is set to a position

TGT

(landing data, variation, motion).

which new data is required a

Selection of destination for

KYBD key is pressed, data may

display/entry by direct entry of

be displayed on the appropri

two digit destination number.

input field of display. To d

number, press the

DATUM

Accesses datum and steering/

corresponding key or keys

(

ROUTE

route functions.

through

9). To display a let

first depress the LTR key

corresponding to the position

the desired letter on a key.

MAL Indicator

Lights when a navigation set mal-

depress the key which contai

Lamp

function is detected by the

the desired letter. Example:

built-in-test circuitry. In the

enter an L, First depress the

event

intermittent

RIGHT key, then depress the

malfunction, the system may

key.

operate correctly but must be

cycled to OFF position tINC an

d DEC Keyssed to increment or decremen

on, to extinguish the MAL light.

the displayed Waypoint/Targe

number when the DISPLAY

switch is set to WP/TGT. T

access P, depress the LTR LEF

BRT and DIM Keys

Used to brighten or dim the light

key followed by the

6 key

intensity of the LCD display.

display way point 99 then depr

the INC key, or display way p

00 then depress the DEC key.

Also used to increment or

Four Line Alpha-

Displays alphanumeric characters,

decrement the Fly-To destinat

Numeric Display

as determined by the setting of

number when the DISPLAY

the DISPLAY switch, the MODE

switchis set toDIST/

switch and operation. keyboard.

BRG/TIME or XTK/TKE/KEY.

The keys activate function upon

release and are to be released

ENT Key

Enters data into memory (as s

immediatelyafter being

up on keyboard and displayed

depressed.

This key is also used for pag

of displays. The bottom rig

corner of the display indic

“morewhen additional pages

TGT STR Key

Stores present position data in the

are available, and “end” when

indicated target store\memory

additional pages are availabl

location (90-99) when depressed

and released.

CLR Key

Clears last entered charact

when pressed once. When

pressed twice, clears entire

field ofdisplay keyboard con

KYBD Key

Used in conjunction with the

keyboard to allow data display

and entry into the compu

F1 Key

Reserved for future growth.

3-34.2

Change

55-1520-240-10

3-61.3. Modes of Operation.

selected and the GPS becomes invalid (para

the AN/ASN-128B will not navigate.

Control of the AN/ASN-128B, including selection of modes

and displays, and entry and readout of da3-61.5.3. Doppler Mode.

the Computer Display Unit (CDU) front panel. The

Doppler position and velocity data are u

AN/ASN-128B has four basic modes of operation: off,

Doppler mode is selected and the Doppler

navigate, test and GPS landing. In navigate mode three

(para.3-61.5.1 abothe, A N / A S N - 1 2 8 B w i

submodes may be selected manually or automatically. These

automatically switch

remembered veloci

are combined mode (default or primary mode of operation),

sensor is not available. If Doppler mode

GPS only mode, or Doppler only mode.

at the start of the flight an initial p

obtained and entered prior to flight. Na

3-61.4. Off Mode.

in latitude/longitude for computational

the same time, distance, bearing and time

In the off mode the system is inoperable. However, the Edge

100 preset destinations are computed

lighting is lighted by an external aircraft power source and is

FLY-TO-DEST).

independent of the AN/ASN-128B mode switch setting.

Edge lighting may not be available if the helicopter is

3-61.6. Test Mode.

modified with the night vision MWO.

The test mode contains two functions:

3-61.5. Navigate Mode.

which all display segments are lit; and T

operation is verified. In lamp test,

In the navigate mode (MGRS or LAT/LONG) pidentical to t

hat of the navigate mode

CDU MODE switch) power is applied tosegments and

the MAL indicator lamp are

components, and all required outputs antheir operation.

In TEST, the RTA no l

provided. The Doppler radar velocity receives elect

romagnetic energy; instead,

measures aircraft velocity, and convertssignals are inserted into the electronic

pitch and roll into digital form. This dathe DRVS. At this time a self test is perf

Receiver (EGR) velocity and position data anavigation computations continue usin

CDU for processing. Baro altitude is usedvelocity.gInhthe

TEST mode, Doppler t

when only three space vehicles are availabldisplayed on theon

CDU front panel for th

is computed by using one of three navig(approximate).

At the end of this perio

which can be selected manually or automdisplayed if there is no malfunction in

submodes are as follows:

failure code is displayed if a malfunct

rotating bar on the display indicates t

3-61.5.1.

Combined Mode (Default or Primary

completed self test. If the navigation s

Mode of Operation).

TEST mode, no navigation data can be displ

front panel. If a Doppler malfunction i

Doppler and GPS position and velocity datindicator lamp lights and DF is displaye

provide navigation. This mode is used whof GPS self test (up to two minutes),

three (with baro) or four space vehiclesreplaced with a complete test result cod

Estimated Position Error (EPE) is less tthe failed circuit

card are also indicated

150 meters, and the Doppler is not indisplay.If GPS

becomes invalid (e.g., due to increased EPE), the

AN-ASN-128B will automatically switch tThe CDU is continuously monitored for

until a valid GPS status is received. Ifown computer as built-in-test-equipment

invalid (e.g., flight over glassy smoomalfunction the MAL indicator lamp on t

memory), the AN/ASN-128B will automaticthe MODE switch on the CDU is set to TE

GPS mode if GPS is valid or an alternate of the failed LRUe

is indicated by a code

GPS is not valid.

Aircraft heading, pitch and roll are a

mode by depressing the ENT key after

3-61.5.2. GPS Mode.

completed. GPS test status is displayed

depressed a secondMa

lfunction codes

GPS positions and velocities are used forautomatically latc

hed and can only be c

Doppler navigation processor in the CDU.the CDU power

via the CDU mode switch (

Change

3-34.3

55-1520-240-10

3-61.7. GPS Landing Mode.

pressed. The position change which occurr

over-flying the fix point is automatical

In the GPS landing mode, the Doppler navigatithe fix point coordinates to complete th

provides information to the HSI indicator fupdate.l-time

landing guidance to a touch down point previously entered in

any of the 100 fly-to destinations. The landiMagneticcvariation can be entered for

determined by present position and the entereddestination, and the system will compute

altitude, glideslope and inbound approach courposition magnetic variation. If operation

in a region with relatively constant

3-61.6. CDU Operation.

variation, the operator enters magnetic

only for present position and the compute

Various required operating data, such as inthis value throughout the flight. If MGRS

position (if GPS is not valid or Doppler modebe entered or

displayed, the MGRS datu

destination coordinates with or without GPS loperation is

also entered.

and magnetic variation can at any time be entered into the

CDU via its keyorathe dataloader viTarget-of-opportunity data can be stored by p

preprogrammed dataloader cartridge. In mSTR (target store) key when the target is ov

data will be entered before the aircraftoperation

stores the coordinates of the target

destination locations in the computer; locatio

The GPS provides present position to the99 sequentiallyfincrementing each time the TGT

GPS is not available or Doppler is selectdepressed. The location is displayed in the

can be initialized as follows:

display field. The computer can keep track o

target positions which may include speeds and

The MODE switch should be set to MGRS or

input by the operator.

LAT/LONG, the WT/TGT display position of the

DISPLAY switch is selected, the Selfiteston

of the AN/ASN-128B is accomplish

number is set to P and KYBD key isbuilt-in-test-equipment (BITE) with the RTA,

coordinates of the initial positionCDU units connected and energized for normal

ENT key is pressed. The computer theSelf test en

ables the unit to isolate failures

changes from the initial position cmain functions (RTA, SDC, CDU or EGR) or to o

the coordinates of the current prescircuit cards in

the SDC or CDU. Self test is a

be read either by remaining in thisfollows:ation or

by setting the DISPLAY switch to PP (present

position) and the MODE switch to MGRSThe

CDU (except for the keyboard and dis

LAT/LONG.

checked on a continuous basis, and any f

displayed by the illumination of the MAL

To update present position over a stored dlamp on the CDU. If the MODE switch on th

KYBD key is depressed and released whenis set to the TEST position, identifica

aircraft overflies this destination. Iffailed circuit card in the CDU is indicat

desired. the ENT key is depressed and releaon theddisplay panel.

the update is completed. The DISPLAY switch is in

the DIST/BRG/TIME position and the FLYThe

DRVS and EGR are tested by setting

DEST is set to this destination during thMODE switch

on the CDU to the TEST posi

The distance-to-go, displayed while over Failure of

the DRVS or EGR are displayed

destination, is the position error of theCDU by illumination of the MAL indicato

moment.

and identification of the failed unit or

indicated by a code on the display panel of

To update present position over a fixed point not

previously stored in the computer, the Continuous monitoring of the Signal

switch is placed PP and KYBD key is depressConverter and Receiver Transmitter Ante

released as the fix point is overflown. provided by

the system status indicati

the display while allowing computation osystem will not use Doppler velocities

in present position to continue within thoperation when flying over glassy smooth

If an update is required, the coordinateHowever, ifix

the system continues to not us

point are entered via the keyboard, and E(e.g., using GPS only when combined has

3-34.4

Change

55-1520-240-10

selected) for excessive periods ofnew data has been entered) causes the d

than 10 minutes) over land or roughmomentarily and return with the latest c

malfunction may exist in the navigaabort a keyboardoperation. move the mode

operator should set the MODE switchto anothero

position.

determine the nature of the failure.

NOTE

The display portion of the CDU is tested by

All keys activate upon release aft

illuminating all the lamp segments in each

depressed. Keys should be depressed

alphanumeric character in the LAMP TEST mode.

immediately released in one continuous

Keyboard operation is verified by observing the

a. Data Entry. To display a letter, firs

alphanumeric characters as the keyboard is

key corresponding to the position of the

exercised.

key. Then depress the key which contains

Forexample, to enter an L, first depress t

3-61.9. Route Sequencing Modes.

then depress the 4 key.

The system has the ability to fly a preprogrammed sequence

of waypoints. This sequence can be eitherb.coKeyboardeCorrection Capability. The

numbered in which case a start and end wayentered may be cleared by depressing the

or randomly numbered in which case all waCLR key isdepressed twice in succession, t

control (indicated by bl

a list and the start and end waypointsbut remains under

sequence modes can be flown in the order valid data enteredt

is displayed.

or in the reverse order. Directions will be displayed to the

way point next on the list until approximc.eD

es10 secondsVariation Constraint.

before overflying the way point at whichvariationdassociated

with a destination

advance to the next way point and the newAFTER the coordinates for that destinatio

will blink for ten seconds. One consecutiorder of entry for present position is ir

sequence may be stored in the system.

d. Impossibility of Entering Unacceptabl

3-61.10.

To-To Route Mode.

cases the computer program will reject unac

example, a MGRS area of W1 does not exis

The system has the ability to provide srejected). If the operator attempts to inse

onto a course defined by the start and endthe unacceptable data will be displayed on

second way point will be over flown. The dtheaselected field will blink after EN

the distance to the course when outside 2 ndisplaying the last

valid data.

course and the distance to the second way point when inside 2

nautical miles of the course.

NOTE

The computer cannot prevent insert

3-61.11.

General Operating Procedures for

erroneous data resulting, for examp

Entering Data.

human or map errors.

The panel display consists of four line LCD readout. The top

e. Procedure for Displaying Wind Speed a

line of the display is reserved for the display of Fly-To

destination number and destination name/International Civil

NOTE

Aeronautic Organization (ICAO) identifier, EPE in meters,

mode of GPS and mode of AN/ASN-128B operatIn MGRS

mode, wind speed isdisplayed i

target store number. The remaining lines wilin LAT/LONG mode,

wind speed is displ

accordance with the DISPLAY and MODE switchknots,en

Wind direction is defined as t

depressing the KYBD key for the first timfrom which the wind originates.

procedure, the display freezes, kybd is displayed in the

bottom right corner indicating the display is(1) Set MODErd

switch to LAT/LONG

mode and the input field under keyboard cmay also be used).it is

not desired to change the display field under control, the pilot

can advance to the next field of the display by(2)pSet DISPLAY switch to WIND-UT

KYBD key again. Depressing the ENT key (andtobserve

display.

Change

3-34.5

55-1520-240-10

(3) The display indicates:

KEY STATUS

TIME

REMARKS

Days or hours

PS daily key

SP;XXXKn

available on

n use and

DIR:XXX°

verified

f. Procedure for Displaying/Entering UTC and

No GPS daily

Displaying GPS Status.

key available

(1) Set MODE switch to LAT/LONGDK

GPS daily key

may also be used).

available but

not verified

(2) Set DISPLAY switch to WIND-UTC/DATA

and observe the wind speed/direction disp3-61.12.

Preflight Procedures.

Required Prior to DGNS Turn-on

(3) Depress ENT key. Observe that a.DataU

display indicates year XX, day XXX and indicates hours,

The following initial data must be entered by

minutes, and seconds of UTC time: XX Hours, XX Minutes,

system turn-on and initialization, unless prev

XX Seconds.

data is satisfactory:

(4) To enter year, day and time depress the KYBD

Datums of operation, when using MGRS coordi

key to select the field for input shown as a blinking field, enter

This data may be part of the data load if prep

the desired data and depress the ENT key.

In combined or GPS mode the GPS provides p

(5) To display GPS status depress theposition.

If the Doppler only mode is selec

display selection menu.

coordinates of present position

- zone area,

northing; latitude/longitude coordinates may al

1> SEA CURRENT

input present position. This data may be part o

2> SURFACE WIND

if preprogrammed. Variation of present posit

3> GPS STATUS

nearest one-tenth of a degree.

4> DATA LOAD end

Coordinates of desired destinations 00 through

y to enter all destinations in the sa

(6) To select the GPS STATUS page deprnecessar

system. This data may be part of the data

key.

preprogrammed.

(7) Observe the CDU display. The display

Variation of destinations to the nearest on

indicated the GPS test mode status as of one of the following:

degree.

GPS TEST: IN PROCESS

Crypto-Key variables necessary to enable t

GPS TEST: NOT RUN

receiver to operate in Y code are entered via r

GPS TEST: PASSED

only and not via the CDU keyboard.

GPS TEST: FAILED

NOTE

g. Procedure for Displaying GPS Key and GPS Space

Destinations are entered manually when stee

Vehicle Status.

information is required to a destination th

not in the set of data loaded via the data loa

(1) Set the DISPLAY switch to XTK/TKE/is d

esired to update present position by ove

a destination, or a present position var

(2) Set the MODE switch to LAT/LONG (MGcomputation is desired. (See CDU operation).

may also be used.

present position variation update is des

destination variation must be entered. T

(3) The display indicates GPS daily operator may enter one or more destinati

time remaining on the currently entered keysvariations: it is not necessary for all dest

Space Vehicles (SV) are currently being usedhave associated variations entered and also

3-34.6

Change

55-1520-240-10

necessary to enter all destinations into be performed. Foraccurate navigation it

variations must be entered AFTER desvariations after each destination unless t

coordinates are entered.

same.

The Doppler outputs true heading and accepts(8) Select

DGNS operating mode (para

heading from gyromagnetic heading reference. If accurate

magnetic variations are not applied, then navigation accuNOTEy

will be affected.

The set will automatically select comb

(default or primary operating mode) as

b. System Initialization

the system to select the best possible

(1) Enter GPS mode “M”.

method available.

NOTE

(9) Set the FLY-TO DEST to the

tination location.

You must select GPS mode “M” durdes

initialization. If “Y” mode is selected before

Crypto-Key variables are loaded the sysc.mProcedure for Downloading Data From

lock-up forever.

Cartridge

(2) Perform self test (para d. below).

(1) Set the CDU mode switch to OFF.

(3) Perform download (para c. below) o(2)aInsert the preprogrammed dat

loader cartridge if necessary, or manuacartridge. datum,

destinations. magnetic variations, and present position (para

f. org. below).

(3) Set the CDU mode switch to

(LAT/LONG may be used). Enterdesired GPS c

(4) LoadCrypto-Keyvariables (unless

mode of operation.

previously loaded and still valid) necessary for operation of

the GPS in Y mode.

(4). Setthe DISPLAY switch to

WIND-UTC/DATA.

NOTE

It is necessary to wait at least 12 minutes for key

(5)To display the select menu depre

validation when new keys have been entered, or

key twice.

collection of almanac data when set has no

previous almanac data. During this time the GPS

1> SEA CURRENT

operating mode must be M and uninterrupted.

2> SURFACE WIND

After this time the GPS operating mode may be

3> GPS STATUS

switched to Y. Observe the GPS Key status and

4> DATA LOAD end

number of SVs tracked after switching to Y mode.

If the SV number goes to zero repeat this

(6) To select the DATA LOADER page d

procedure. The Key status shall switch from DK

the 4 key.

IN to DK OK sometime during the 12 minutes.

DATA LOADER

(5) Check datum of operation, if MGRS is being

used.

ENTER DATA: N

end

(6) Check destinations in MGRS or LAT/LONG

coordinates as desired.

(7) To begin the download depress the

(7) Check associated destination enter Y (yes)

desired. Remove all incorrect variationsby setting DISPLAY

switch to WP/TGT, setting the destination (8) Observe the CDU display. The

appropriate destination, and depressing tdisplay DOWNLOAD WAYPTS and WAIT ACK.

ENT key in that order. Variations of at ltransmission error occurs the CDU display

must be entered for automatic variation

ERROR-RETRYING.

Change

3-34.7

55-1520-240-10

(9) When the transmission is complete the CDU

(a) All edge lighting is illuminated.

shall display DOWNLOAD WAYPTS COMPLETE. If this

display is not obtained within one minute of beg(b) All keyboard keys are illuminated.

download check the data programming and connections.

(3) Set MODE switch to TEST.

(10)Set the CDU mode switch to OFF, remove

the data loader cartridge if desired, and then s(a) While

test is performing, depre

mode switch to the desired setting.

DIM pushbutton several times, then the BRT p

several times. The LCD display should glow di

d. Self-Test

brighter. Adjust LCD display for comfortable

(1) Set the MODE switch to LAMP TEST. Enter

(h) After Doppler and/or GPS self tests

GPS mode “M” or “Y”. Verify the following:

completed (approximately 15 seconds for Dopple

minutes for GPS), one of the following disp

(a) All LCD on four-line display are

observed in the left and right displays:

illuminated.

NOTE

(b)The MAL lamp is illuminated.

In the event the TEST mode display is not

(2) Rotate the center console lightiALL the system should be recycled through O

Verify the following:

to verify the failure is to a momentary on

LEFT DISPLAY

RIGHT DISPLAY

REMARKS

Doppler has completed Built in Test ( BIT) and is

factorily, GPS is still performing BIT (GPS has

cycle maximum). Note that a rotating bar in the d

that the GPS is still performing self test.

ALL

The entire system has completed BIT and is operati

rily.

Pitch or Roll data is missing or exceeds 90°. In

and roll in the computer are both set to zero and n

Doppler mode continues with degrade operation. P

be in the vertical gyro or aircraft cabling.

C.R.S. or H followed Ayfailure has occurred in the Computer Display Un

a numeric code

nal Data. Converter Power Supply. The operator sh

the system

GPS failure code

GPS has failed but operator can use doppler to pe

gation.

Doppler failure code Doppler has failed. GPS is still performing self

Doppler failure code Doppler has failed but operator can use GPS to pe

gation.

3-34.8

Change

55-1520-240-10

e. Procedure for Displaying or Selectin9.GASYM

will be displayed. Depress ENT

Operating Mode, Doppler, GPS, or Combindisplay will blank out for less than one s

and Displaying Groundspeed and Track.

display will now indicate: Y.

(1) Set MODE switch to MGRS positi(5) Selection of DGNS mode of operat

(LAT/LONG or GPS LDG position may also be used).

As an example, consider selection

mode of operation. Depress KYBD key twice

(2) Set DISPLAY switch to GS/TK/NAV M.

the DGNS mode blinks. To enter G (for GPS

(3) The display indicates the curkey LTR LEFT

followed by key

3. A G wil

navigation mode on the top line:

Depress ENT key. The entire display will

than one second and the DGNS Mode will no

(a) Selected Fly to waypoint.

(or * if GPS is not available).

(6) Ground Speed and Ground Track An

(b) EPE (GPS Estimated Position Error in

displayed on lines 3 and 4.

Meters. An asterisk (*) in the character position of the EPE

display indicates an EPE of greater than

999 or data

f. Procedure for Entering/Displaying Pres

unavailable.

One of the 100 Possible Destinations in M

(c)GPS mode of operation:

The DGNS has the capability to display

(numbered 00 through 99).

M for mixed C/A and P/Y code GPS

reception

100 destinations

Y for only Y code GPS reception

-00 to 69 Standard Waypoints

(d) DGNS mode of operation:

-70 to 89 Data Load-only Waypoints,

Observable but not changeab

C for combined Doppler and GPS

CDU keyboard. Used for Nat

Airspace Data Such as VORs,

D for Doppler only

NDBs. and intersections.

G for GPS only

-90 to 99 Target Store Waypoints (Usa

Standard Waypoints)

R for remembered velocities

As an example, consider display of desti

* for no navigation.

(1) Enterdatum asdescribed in paragra

(e) Target destination where the present

(2) Set MODE switch to MGRS.

position will be stored next time TGT/STR is depressed.

(3) Set DISPLAY switch to WP/TGT.

NOTE

(4) Notice the current destinat

In MGRS mode, ground speed is displayed in

displayed. To display destination number 2

km/hr; in LAT/LONG mode, ground speed is

or DEC keys, or depress keys 2 then 5. Th

displayed in knots.

entry action.

Only mode C, G, and D may be selected as the

primary navigation mode. Modes R and

* a(5) Observe that the current desti

automatic fall back modes used when zonearea, and easting/northing coordina

Doppler and GPS are unavailable.

displayed. The destination number

name/ICAO identifier also appears in the

(4) Selection of GPS mode of operation:

(6) Entry for destination coordinates

As an example, consider selection oname/ICAO identifier: As an example, consi

Depress KYBD key. Observe that the GPS mo18T, area WN, easting

5000, northing

enter Y (for Y mode) depress key LTR LEFTidentifier BANDO.

Change

3-34.9

TM 55-1520-240-10

(7) To enter keyboard mode depress or DECD

keys, or depress keys 2 then 5. This i

key. Observe “kybd” displayed in the botentry action.ner of

the display. (Destination number blinks.) Depress KYBD

e1,8,

that the current Latitu

again. (Zone field blinks.) To enter

18T depr(5)Obs

Longitude coordinates are now displayed. The

LTR MID.

number 25 and location name/ICAO identifier a

(8) Depress KYBD. (Area and northdisplay.ing

blinks.) To enter WN5000 6000 depress keys LTR MID, 8

(6) Entry of destination coordinates and

LTR MID,

5, KYBD,5,0,0,0,6,0,0,0.

name/ICAO identifier: As an example, consid

Latitude N41°

10.13 minutes and longitude E

(9) Depress KYBD. (Location name/ICAO

minutes and ICAO identifier BANDO.

identifier blinks.) To enter BANDO depress keys LTR MID,

1, LTR LEFT, 1, LTR MID, 5, LTR LEFT, 2, LTR RIGHT, 5.

(7)To enter keyboard mode depress KYBD

Observe “kybd” displayed in the bottom right

(10)To store the displayed information into the

display. (Destination number blinks.) Depress

selected destination display position depress the ENT key.

(Latitude field is blinks.) To enter N41° 10.

N,4,1,1,0,1,3.

NOTE

To access P, depress the LTR LEFT key follo(8) Depress KYBD. (Longitude field blink

by the 6 key. Another way to access P ienter E035°

50.27 depress keys E,0,3,5,5,0,2,7

way point 99 then depress the INC key or display

way point 00 then depress the DEC key.

(9) Depress KYBD. (Location name/;l

identifier blinks.) To enter BANDO depress ke

Way points cannot be recalled by location

1, LTR LEFT, 1, LTR MID, 5, LTR LEFT, 2, LTR

name/ICAO identifier.

(10)To store the displayed information

g. Procedure for Entering/Displaying Present Position

selected destination display position depress

or one of the 100 Possible Destinations in LAT/LONG.

Display indicates:

The DGNS set has the capability to display

100

destinations (number 00 through 99).

N41° 10.13 E035° 50.27.

100 destinations

NOTE

To access P, depress the LTR LEFT key foll

-00 to 69 Standard Waypoints

by the 6 key. Another way to access P is to

way point 99 then depress the IUNC key or di

-70 to 89 Data Load only Waypoints,

way point 00 then depress the DEC key.

observable but not changeable via

Waypoints cannot be recalled by locati

CDU keyboard. Used for National

name/ICAO identifier.

Airspace Data such as VORs.

NDBs, and intersections.

h. Procedures for Entering Variation and Lan

Data

-90 to 99 Target Store Waypoints (Usable as

Standard Waypoints)

(1)Set MODE switch to MGRS position-alt

entered/displayed in meters (LAT/LONG may

As an example, consider display ofdestinused-

altitude entered/displayed in feet).

(1) Enter the datum as described in parag(2) Set

DISPLAY switch to WP/TGT positio

below.

(3) Select the way point number desi

(2) Set MODE switch to LAT/LONG.

directly entering the two digit target number

INC/DEC keys. Observe the way point number en

(3) Set DISPLAY switch TO WP/TGT.

position data.

(4) Notice that the current destination n(4)rDepress the ENT key and observe

displayed. To display destination number

way point number, variation and/or landing da

3-34.10

Change

55-1520-240-10

(5) To enter a magnetic variation and/or(4) Depress the ENT key and observe t

mode data depress the KYBD key to select speed and direction

page.

and enter the desired data as shown in steps 6 through 10

elect target speed depress th

below. To end the entry operation depress the (5)To s

twice and enter the target speed. The maxi

(6) Entry of variation: as an exathat may be entered is

50 knots. Fill le

entry of a variation of E001.2. Depress entering.0,1 and 2.

The decimal point is inserted automatically. If no landing

(6) To select the target direction

mode data is to be enter depress ENT to complete the

KYBD key and enter the target direction.

operation. Display indicates: E001.2°

(7)To end the entry operation depres

NOTE

key. At the time the ENT key is depressed

An asterisk appearing in the variattarget position will begin to be updated a

indicates the variation is not enterebased on thes

speed and direction entered.

may not be entered for waypoints containing

NOTE

target motion.

To abort/cancel and entry of target mot

(7) The bottom two lines indicate target speed of 000 using the above pro

altitude, desired glideslope, and the desired inbound

approach course (IAC) to the indicated dej. Procedure for

Entering/Displaying Datu

example, consider entry of a glideslope oAll°Waypoints 270°,

and an altitude of +230 meters. for destination number 25.

(1) Set the MODE switch to MGRS

(LAT/LONG may also be used).

(8) Depress the KYBD key to blink the altitude

field. Depress the INC/+ key to enter a positive altitude,

(2) Setthe DISPLAY switch to

depress keys 2,3,0 (the leading zeros may be omitted) for the

DATUM/ROUTE.

altitude of 230 meters in the example.

(3) To select the datum field depres

(9) Depress the KYBD key to blink theKEY.de slope

field. Enter glideslope. The maximum allowable glideslope

9 degrees. In the example enter

8 for an (4) Entry of

datum: as an example con

glideslope.

25. Depress keys LTR

2,5. Depress the

display shall show DATUM:25.

(10)Depress the KYBD key to blink the inbound

(5) To clear all waypoints, varia

approach course field. Enter a three digit inbound approach

data and target motions, enter RDW for the

course angle. In the example enter 2,7,0 to enter a 270 degree

inbound approach course. Depress the ENT key to complete

k. Procedure for Entering Sea Current

the operation.

Direction for Water Motion Correction.

i. Procedures for Entering Target Motion and Direction

NOTE

In MGRS mode, wind speed isdisplayed in

In MGRS mode, target speed is entered in km/h; in

in LAT/LONG mode, wind speed is displa

LAT/LONG mode, target speed is entered in knots.

knots. Leading zeros must be entered. Se

direction is defined as the direction

(1) Set the MODE switch to LAT/LONG (MGRS

flowing.

may be used).

(1) Set MODE switch to LAT/LONG

(2) Set the DISPLAY switch to WP/TGT and

may be used).

select the target number desired (00-69 or 90-99) by directly

entering the two digit target number or INC(2) Set DISPLAY switch to WIND-UT

Observe the way point number entered and and observe t

he standard wind speed and di

(3) Depress the ENT key and observe (3)

Depress the ENT key twice to

way point number, variation and/or landi

selection menu

Change

3-34.11

55-1520-240-10

1> SEA CURRENT

3> GPS STATUS

2> SURFACE WIND

4> DATA LOAD end

3> GPS STATUS

4> DATA LOAD end

(4) Depress the 2 key to select SURFACE WI

The display indicates:

(4) Depress the 1 key to select SEA CURRENT.

The display indicates:

SURFACE WIND

SP:XXXKn

SEA CURRENT

DIR:XXX°

SP:XXXn

DIR:XXX°

(5) Entry of wind speed and direction:

example, consider the entry of 20 knots and 1

(5) Entry of sea current speed and direction: as an

Depress KYBD key. Observe that the wind speed f

example, consider the entry of

4 knots and

135 degrees.

Depress KYBD key. Observe that the speed field blinks.

(6)To enter speed, depress keys 0, 2 and

wind speed indicates 020. The maximum surface w

(6)To enter speed, depress keys 0,0 and 4. The

is 50 knots.

speed indicates

004Kn. The maximum sea current speed that

may be entered is 50 knots.

(7) Depress KYBD key. The direction d

(7) Depress KYBD key. The direct blinks.play

blinks.

(8)To enter direction, depress keys 1, 5

(8) To enter direction, depress keysWind direction indicates 150°.

Direction indicates

135°.

(9) Depress ENT key. The display momenta

(9) Depress ENT key. The display momentarily

blinks and then reappears.

NOTE

To abort entry of surface wind speed a

To abort entry of sea current, enter a sea current

direction, enter a surface wind speed of 000

speed of 000 using the above procedure.

the above procedure.

1. Procedure for Entering Surface Wind Speed and

3-61.13. Flight Procedures.

Direction for Water Motion Correction.

NOTE

Not required or necessary when in combinThisrprocedure is applicable to the Dopple

GPS mode. In MGRS mode, surface wind speedmode. Present position is automatically up

entered in km/hr; in LAT/LONG mode, surwhen

DGNS is in combined mode.

wind speed is entered in knots. Leading zeros

must be entered. Wind direction is defia.dUpdating Present Position from a Stored De

direction from which the wind originates.

NOTE

(1) Set MODE switch to LAT/LONG (MGRS

The preface is: The aircraft is flying

may also be used).

destination, that is, the FLY-TO Destinatio

to the number of the desired destination.

(2) Set DISPLAY switch to WIND-UTC/DATA

and observe the wind speed/direction display.

(1) Set DISPLAY switch to DIST/BRG/TI

(3) Depress the ENT key twice to position. Distance, bearing and time-to-go t

selection menu.

destination are displayed.

1> SEA CURRENT

(2) When the aircraft is over the des

2> SURFACE WIND

depress KYBD key. Observe that the display fre

3-34.12

Change

55-1520-240-10

(3) Position update can be effected by depr(3)Depress KYBD key. Observe that th

the ENT key. The computer updated the prefreezes.sition at

the time the KYBD key was depressed by using the stored

enter the landmark coord

destination coordinates, and adding to them (4) Manually

traveled between the time the KYBD key wadepressing thed

KYBD key to blink the field t

ates.

the ENT key was depressed. In addition,enter the coordin

variation for the stored destination exists, the present position

(5) When overflying landmark, depress

variation is also updated.

(6) If an update is not desired, set

(4) If a present position update is unnecessary (as

switch to some other position. This action

indicated by an appropriately small value of DISTANCE to

mode.

go on overflying the destination), set the DISPLAY switches

to some other position - this action abort61.14. Fly-update mode.

To Destination Operation.

b. Updating Present Position from a Landmark

a. Initialization of Desired Course

NOTE

When a fly-to destination is selected such

There are two methods for updating leg, the present position at the time is s

position from a landmark. Method

A course is then computed between the select

particularly useful if the landmark

destination. If the aircraft deviates from

ral offset or crosstrack distance

unexpectedly and the operator needs the late

determine the coordinates. Method

2 is useful

Distance and bearing to destination, actual

when a landmark update is anticipated.

track angle error correction are compute

position to destination. See figure

3-15

Method 1 (Unexpected update)

definition of these terms.

(1) Set DISPLAY switch to PP position.

b. Procedure for Selecting One of 100 Po

Destinations (Direct Mode)

(2) Overfly landmark and depress KYBD key.

The present position display shall freeze.

The Doppler/GPS navigation set has the

selecting a fly-to destination from 100 d

(3) Compare landmark coordinates with those on

00 through 99).

display.

As and example, consider selecting Fly-

(4) If the difference warrants an update, enter the

number

43.

landmark coordinates by depressing the KYBD key to blink

the field to be changed, enter coordinates, then depress the

(1) Set MODE switch to MGRS (LAT/LON

ENT key. The computer updates the present position (from

GPS LDG may also be used).

the time the KYBD key was depressed) to the landmark

coordinates, and adds to the updated present(2) Set DISPLAY switch to XTK/TKE. O

distance traveled between the time the standard Cross Track (XTK) and Track angl

depressed and the ENT key was depressed.

display. (DIST/BRG/TIME may also be used)

(5) If an update is not desired, set the(3)ToAY

display Fly-To destination 43

switch to some other position. This actioINC or DEC keys, or

depress keys 4 then 3

mode.

key entry action.

Method

2 (Anticipated update)

Left-Right Steering Signals

(1) Set DISPLAY switch to WP/TGT posiThere

are two methods the pilot may

destination, using left-right steering sig

(2) Access P by depressing the LTR computer-display unit. Left-right steerin

followed by the

6 key, entering destiused when flying the shortest distance to

depressing the DEC key, or entering despresent

position

(Method 1) or when flyin

depressing the INC key.

from start of leg to destination (Method

Change

3-34.13

55-1520-240-10

METHOD

(6)Depress KYBD key. (END field bl

enter ending destination 45 depress keys 4

When flying shortest distance to destination from

present pos

set DISPLAY switch to

(7) Depress KYBD key. (SELECT field

DIS/BRG/TIME position and steer Enter Y (yes) for mode selection. N may be

bearing displayed. As an aid to maisystemgwithrsthe start and end destinati

set DISPLAY switch to XTK/TKE posenteringd

the Route-Sequence To-To mode,

steer aircraft to keep track anglroute-Sequence

To-To mode if the system is

nominally zero. If the display indmode.s a L (left)

TKE, the aircraft must be flown to the left to zero the

NOTE

error.

If an entry is changed after Y is e

METHOD

selection, and N must be entered for th

then it may be changed to Y. The sequence

When flying a ground track, set DISPLAYflown from

the beginning waypoint.

XTK/TKE position. Steer vehicle to obtain zero for

No target destinations or destinations

crosstrack error (XTK). If XTK is left (L), aircraft is

motion may be included as To-To waypoi

to right of the desired course and must be flown to

the left to regain the initial course.

d. Procedure to Enter Route-Sequence Ran

NOTE

The Doppler/GPS navigation set has the

Since the aircraft has the Horizontanavigate through a sequence of random

Indicator (HSI) and when the Dopplerdestinations.

selected then the pilot may use the “#1” needle and

ple, consider navigating thro

course deviation indicator (CDI) for naAs an exam

the Fly-To destination selected on thnumbers 32, 25, 74, 01, 48, 83, 35.

(1) Set MODE switch to MGRS (LAT

Select CDI by depressing, then releasing the DPLR GPS

may also be used).

lens on the HSI Mode Select Panel.

(2) Set DISPLAY switch to DATUM/ROU

c. Procedure to Enter Route-Sequence To-To Mode

(3) Depress the ENT key. Observe that

The Doppler/GPS navigation set has the capability to

special steering functions appears.

navigate a course set up between to destinations.

(4) To select the Route-Sequence

As an example, consider navigating onto a course starting

display depress key 2. Observe that RT SEQ

from destination number

62 and ending at destination

appears in the display followed by th

number 45.

destination numbers and a continuation pr

(1) Set MODE switch to MGRS (LAT/LONG

(5) Enter the sequence of destination

may also be used).

depressing the KYBD key to enter keyboar

destination field is blinks.) To enter

(2) Set DISPLAY switch to DATUM/ROUTE.

depress keys 3, 2.

(3) Depress the ENT key. Observe that a menu of

(6) Depress KYBD key. (next destinat

special steering functions appears.

blinked.) Depress keys 2., 5 to enter seco

(4) To select the Route-Sequence To-To di(7)yRepeat step

6 until a maxim

depress key

1. Observe that TO-TO and sdestinations

are entered or if less than

appears in the display. The display proviasterisks are left f

or remaining destinat

and ending destination numbers.

(8)To complete the entry of the rando

(5) To enter keyboard mode depress of waypoints depress ENT key.

key. (START field blinks.) To enter starting destination

depress keys 6, 2.

(9) Depress ENT key to select next pa

Change

3-34.15

55-1520-240-10

(10)To select the start field and enter t(7) Depress

KYBD key. (SELECT field bli

destination depress KYBD key.

Enter Y (yes) for mode selection. N may be ente

system but without entering the Route-Se

(11) To select the ending field Consecutivehe

mode, or to exit the Route-S

ending destination depress KYBD key.

Consecutive mode if the system is currently in

entry of Y and R indicates a choice of Y-flyi

(12)Depress KYBD key. (SELECT fieldorder, or

R-flying in reverse order.

Enter Y (yes) for mode selection. N may beentered to arm the

system but without entering the Rout-Sequence Random

NOTE

mode, or to exit the rout-Sequence Random If an entry

is changed after Y or R is en

system is currently in that mode. An entry Y selection, and N

must be entered for the s

choice of Y-flying in forward order, or R-then it may be changed to Y or R. the seq

order. To clear the random sequence, enter amust be flown from the beginning waypoint

No target destinations or destinations wit

NOTE

motion may be included as Route sequenc

If an entry is changed after Y or R is econsecutive waypoints.

selection, an N must be entered for the selection

cedure for Displaying Distance/Bea

then it may be changed to Y or R. The sf. Pro

Information

must be flown form the beginning waypoint.

No target destinations or destinations with target

(1) Set MODE switch to MGRS (LAT/LONG o

motion may be included as Route sequence

GPS LDG may also be used)

random waypoints.

(2) Set DISPLAY switch to DIS/BRG/TIME.

(13)After all entries are made, depress ENT key.

(3) Observe that the distance-to-go in k

e. Procedure to Enter Route-Sequence-Consecutive

(to the fly-to destination), bearing, and tim

Mode

the bottom two lines of the display. (Distan

miles when MODE switch position is LAT/

The Doppler/GPS navigation set has the capability to

Bearing-to-destination is displayed in degr

navigate through a sequence of consecutively numbered

time-to-go is displayed in hours, minutes, a

destinations.

minute.

As an example, consider navigating through destination(4)The display of the second line depend

numbers 32 through 35.

current steering mode as follows:

(1) Set MODE switch to MGRS (LAT/LONG

(a) Direct-To Steering (default):

may also be used).

destination number and ICAO identifier are

Example:

58:BANDO

(2) Set DISPLAY switch to DATUM/ROUTE.

(b) To-To Steering: TO-TO-:XX TO

(3) Depress the ENT key. Observe thatwhere XX is the ‘To-To’ start-of-leg destinat

special steering functions appears.

YY is the ‘To-To’ fly-to destination number.

(4) To select the Route-Sequence-Consecuti(c) Route-SequeSteering(both

display depress key 3. Observe that RT SEconsecutivew

and random): RT-RANDOM:XXTOYY w

appears in the display, followed by stXX is the current

Route-Sequence fly-to desti

destination numbers, and mode selection.

and YY is the next destination number in th

Approximately

10 seconds before overflying

(5) To enter keyboard mode depress destination, the system automatically ‘pickl

key. (START field blinks.) To enter stardestination, and

the new fly-to number blinks

depress keys 3, 2

then stops blinking.

(6) Depress KYBD key. (END field g. Procedure for Displaying Present Positio

Depress keys 3, 5 to enter ending destinaAltitude

3-34.16

Change

55-1520-240-10

(1) Set the MODE switch to MGRS (LAT/LONG6) If it is not desired to store the

or GPS LDG may also be used). Set the DISDISPLAYiswitch

momentarily or permanently

PP and observe present position display.

position.

e for Entering Landing Mode

(2) To display present position variati. Procedur

altitude depress the ENT key. Present position variation may

(1) Set the Fly-to destination by

be entered by depressing the KYBD key to select the

DISPLAY switch

itherX T K / T K E / K E Y o r

variation field. A variation is entered and the ENT key is

DIST/BRG/TIME. Directly enter the two di

depressed.

number or use the INC or DEC keys.

h . Target Store (TGT STR) Operation

(2)Set MODE switch to GPS LDG.

Two methods may be used for target store o(3)The DISPLAY switch continues to fu

Method

1 is normally used when time isbefore. To switch

between metric and Engli

preplan a target store operation. Method the ENT key.n time

is available and it is desired to store a target in a specific

location.

NOTE

In this mode, the DGNS provides rea

Method 1 (uses location 90-99)

landing guidance information to th

indicator. To display course deviation

(1) Depress the TGT STR key while flyi(CDI)er

on VSI and HSI, depress then rel

target.

DPLR GPS button on the HSI Mode Select P

(2)

Present

position

and

variaj.P

rocedure for Transferring Stored Dest

on to Another

automatically stored in the target destiData From One Locati

was displayed in the target store field immediately prior to

The following procedure allows the opera

depressing the TGT STR key.

stored destination/target data from one

location to another destination location.

Method 2 (uses locations 00-69 and 90-99)

consists of destination name/ICAO ident

variation, and landing information. For i

(1) Set MODE switch to MGRS or LAT/LONG

only, it is assumed that the operator w

position, depending on coordinate from desired.

coordinates of stored target

97 into t

destination 12.

(2) Set DISPLAY switch to WP/TGT position.

(1)Set DISPLAY switch to WP/TGT posi

(3) To access P, depress the LTR LEFT key

followed by the 6 key. Another way to access P(2) Depress keys

9 then 7.

way point 99 then depress the INC key ordisplay way point 00

(3) Depress KYBD key, depress keys 1 t

then depress the DEC key.

NOTE

(4) Depress KYBD key when overflying potential

target. Observe that display freezes and kybLocation name/ICAO identifier, variat

the bottom right corner of the display indlanding data may

be deleted by first di

mode. The destination number is now underwaypoint,

depressing the KYBD key, th

control indicated by a blinking field.

ENT key.

CAUTION

(4) Depress ENT key.

k. Operation During and After a Power In

Do not depress ENT key while destination is set to

During a power interruption, the stored

target data and present position are retai

(5) If it is desired to store the taRAM inside the CDU. This makes it unnecess

digit destination number and depress the

any navigation data when power returns. GP

Change

3-34.17

55-1520-240-10

are also retained by a rechargeable battery in(3) Observe the CDU display. The top indic

This makes it unnecessary to reload the crin degrees and tenths of a degree, aircraft sy

the collection of any almanac. Navigationpitch, and roll.pted

during the absence of power; however the present position

will be updated when the GPS data becomes valid provided

nd Indicators - Horizontal

the DGNS mode has not been selected as Do3-61.15.r oControlsa

g. 3-15.3.)

pilot will have to re-enter the GPS operating mSituation(Indicators.Y(fi

using a single key (5 or 9).

CONTROLS/

In the event the CDU is initialized, the display will indicate

INDICATOR

FUNCTION

only EN when the CDU is operated. This is an indication to

the operator that previously stored data has been lost and that

spheroid/variation, destinations, and calibration data must be

Compass Card

The compass card is a 360° scale

entered. Present position needs to be entered only if Doppler

that turns to display heading d

only mode has been selected. The KYBD key must be

obtained from the gyro magneti

depressed to clear the EN.

compass (AN/ASN-43). The

helicopter headings are read a

The computer initializes to the following: operating mode

the upper lubber line.

to combined, present position variation to E000.0,

destinations and associated variations to a non-entered state,

wind speed (water motion) and sea currenBearing Pointer

The 1pointeroperatesin

DATUM:

00, present position to N45°

00.00' E000°00.00’

conjunction with doppler/GPS

(until

updated by GPS), target store location to

91, alInd

icates magnetic bearing to

track calibration correction to

00.0 percent, and magnedop

pler/GPS destination set on

compass deviation corrections to

000.0 degrees. The

FLY-TO-DEST.

following data must be entered:

(1) Depress KYBD key.

Bearing Pointer The 2pointeroperates in

conjunction with selected VOR

(2) Set MODE switch to OFF momentarily, to

or ADF receiver. The pointer

LAMP TEST for approximately one second, and then to

read against the compass card

MGRS or LAT/LONG.

and indicates the magnetic

bearing to the VOR or ADF

(3) Select GPS M or Y mode.

station.

(4) Select DGNS operating mode if other than

combined.

Course Deviation

his indicator indicates later

cator

deviation from a selected VOR

(5) Enter datum.

course or doppler computed

course or heading in the case

(6) Enter present position if Doppler only has

FM homing. When the helicopter

been selected.

is flying to correct course,

course indicator will be alig

(7) Enter each destination and its associated

with the course pointer and w

variation.

be centered on the fixed aircr

1. Procedure for Displaying Aircraft Heading, Pitch, andymbol. The two dots on eithe

side of the indicator indica

roll (Maintenance Function)

amount of course deviation. On

(1) Set the CDU mode switch to test and observe

dot displacement is equivalent

the CDU test mode display.

5° off VOR or doppler and 1 1/

degrees off localizer course

(2) After the Doppler test iscompleted depress the

These displacements do not

ENT key.

apply to FM homing.

3-34.18

Change

55-1520-240-0

CONTROL/

FUNCTION

CONTROL/

FUNCTION

INDICATOR

CRS Knob

The COURSE indicator and

Course Indicatorcourse pointer operate in course

Glide Slope PoinDisplays glide slope p

Pointer

conjunction with

the course

relative to the helicopt

select (CRS) knob, and allow the

homing signal strength.

pilot to select any VOR course.

pointer

bove center,

The course pointer turns with the

helicopter is below glid

compass card and will be aligned

conversely

pointer is

with the lubber line when the

below center, helicopter

helicopter heading is the same as

glide slope. Increasing

the selected course.

signal strength is sho

pointerrisingDecreasing

Range Indicator

Digital distance display in

homing strength is show

kilometers (KM) to destination

pointer falling.

set on doppler FLY-TODEST

thumbwheel.

HDG Knob

Heading select (HDG) kGlide Slope (GS)Indicates loss of or an

Flag

glide slope or FM homing

operates in conjunction Warning

heading bug. It allows the pilot to

select any one heading. With

CMD SEL (fig. 3-14) selec3-61.16.Horizontal Situation Indicator Mode

the HSI MODE SELECT panel,

Select Panel. (fig.

3-15.3)

the AFCS (chapter

2) will turn

the helicopter to and maintain the

selected heading.

The HSI MODE SELECT panel is on each pil

panel below the HSI. The panel allows the

HDG Flag

The HDG flag is in view when

navigation mode to be displayed on the HSI

the signal from the gyro magnetic

heading select feature, and visually indi

compass is unreliable or power to

passage. The panel isdivided into threese

the indicator is lost.

BRG, and MKR BCN,

To-From Arrow

To-from arrow indicates that the

helicopter is flying to or away

a. The CRS (course) section consists of

from a selected VOR.

selector switches labeled VOR SEL, GPS/

NAV Flag

The NAV flag turns witSEL,e

and CMD SEL. Pressing VOR SEL, GPS/D

compass card. The flagFM SEL causes the output of the selected na

retract from view when aelectrically connected to the course devi

VOR doppler or FM homicorresponding HSI and lights SEL legend

signal is being appliedThese switches are electrically interloc

instrument.

may be selected at a time. Selecting an

modes, automatically disengages the mode

Aircraft Symbol Corresponds to longitudithe SEL

legend of the mode in use, enga

of the helicopt

shows

mode, and lights the SEL legend of the se

helicopter position andpilot may independently select different

relative to the selected forrdisplay on his HSI.

Change

3-34.19

TM 55-1520-240-10

b. Pressing CMD SEL engages the AFCS headtwo segments labeled VOR and ADF. If the

feature, causes the helicopter to turn tolit, the No.,h2 pointer will indicate

to which the HSI heading bug is set, and station to which the VHF navigation set is

legend on the switch. Due to electrical iswitch will cause the VOR segment to go

two HSI control panels, both CMD SEL swipointer will indicate the bearing to th

engaged at the same time. The engaged switcADF set is tuned out and light the AD

the lit SEL legend. If the opposite CMopposite actions

occurs if the ADF segme

pressed when operating with heading selecswitch is pressed.

AFCS panel will release and heading select will be

disengaged. Control of the course deviatiod. A MKR BCN light will illuminate

VOR mode relative to bearing and coursebeacon passage. The light labeled O comes

from a VOR is assigned to the pilot whothrough an outer marker beam. The light la

engaged. If the pilot who does not have Cwhen passing through a middle marker and

makes an adjustment on his CRS knob, it wlabeled I comes on

when passing through an

on the CDI relative to the course.

each light illuminates, a distinctive

beacon will be heard over the interphon

c. Pressing VOR/ADF pushbutton on thlights have a press-to-test feature; pre

selects the navigational aid, the bearinthree lamps will cause all mode select p

indicated by the HSI No. 2 pointer. The stotilluminatedon that HSI MODE SELECT p

Change

3-34.21

55-1520-240-10

SECTION IV TRANSPONDERS

3-62. Transponder System (AN/APX-100).

CONTROLS/

INDICATOR

FUNCTION

The transponder system provides automatic radar iden-

tification of the helicopter. The syM-1, M-2, M-3/A SA

itONes

position, the appli-

codes, and replies to interrogations on modes

3/Acble mode is selected for

4, TEST and C from all suitably equipped challenging

operation. OUT position

helicopter or ground facilities. The receiver sectioturns off applicable mode.

operates on a frequency of

1,030 MHz and the trans-

At TEST position, that

mitter section operates on

a frequency of

1,090 MHz.

particular mode is tested

Because these frequencies are in the UHF band, the

for proper operation. If

operational range is limited to line-of-sight. Power te

st is valid, TEST lamp

operate the system is supplied by the No.

2 DC bus

will illuminate.

through the COMM IFF circuit breaker on No.

2 PDP.

M-C

In mode C, altitude infor-

The integral receiver-transmitter-control panel is on mation is provided to

console. It provides the control switches for applicatground controllers by the

of power, setting of the -modes and codes, modes of

AAU-32A encoding altim-

operation, identification of position, and emergencyeter. Switch position func-

functions of the set. It receives coded interrogatintons are the same as for

pulses and tests them for validity. If the signals confM-l, M-2, and M-3A

to the preset mode and code, a coded reply is transmit-

switches.

ted. Additional preset codes for emMODEc1 Selecto

Selects and indicates a

available when selected. These emergeSwitcheses are

two digit

32 code reply

transmitted on modes

1,2,3/A and

4 regardless of codes

number.

selected. Transponder functions are continuously mon-

MODE

2 Selector

Selects and indicates a

itored by built-in-test circuits. Each mode also has a

Switches

digit

4096 code reply

self-test feature which can be selected by the pilot to

number. (Switches are

verify operation. The RT-1285/APX-100 is the interim

preset and covered by a

NVG compatible control. The RT-1558/APX-100 is the

guard. Only the reply

NVG Blue Green version. Both units are form, fit and

code can be seen.)

functionally interchangeable. The receiver-transmitter

must be removed from the console to rMODEc3/A Selector

Selects and indicates a

Switches

digit

4096 code reply

3-83. Controls and Function, Transponder Control

number.

(RT-1285/APX-100)(RT-1558/APX-100).

(fig.

3-16)

MODE

4 CODE ContSelects type of MODE

Switch

operation.

CONTROLS/

HOLD

This function is enabled

INDICATOR

FUNCTION

only when the right aft

MASTER Control

landing gear strut is com-

Switch:

pressed. It holds the

OFF

Removes power from

MODE

4 code which

transponder set and com-

would otherwise be

cleared when the set is

puter.

turned off or electrical

STBY

Power is applied to tran-

power is removed. Switch

sponder receiver and com-

is spring-loaded to A.

puter; transmitter inoper-

HOLD function is reset

ative. Set ready for

when the transponder is

operation after

2 minute

turned on.

warmup in STBY.

Enables transponder to

NORM

Transponder in normal

reply to code A interroga-

operation.

tions.

EMER

Transmits emergency re-

Enables transponder to

ply signals to mode

reply to code B interroga-

3/A and

4 interroga-

tions.

tions, regardless of mode

control settings.

3-34.22

Change

TM 55-1520-240-10

CONTROLS/

INDICATOR

FUNCTION

INDICATOR

FUNCTION

ZERO

Clears (zeroizes) mode

RAD TEST feature is

inoperative.

code settings in transpon-

der computer.

IDENT-MIC Switch

At IDENT, the set will

transmit a coded identifi-

MODE 4 AUDIO

At AUDIO, the REPLY

indicator light will illumi-

cation pulse for about 20

LIGHT OUT Switch

nate when the transpon-

seconds to all interrogat-

der replies to valid mode

ing stations on modes 1, 2,

4 interrogations. A pulse

and 3/A to identify the

helicopters position. OUT

tone will be heard in the

headset when a code A

position turns off the

interrogation is received

identification pulse. MIC

but the CODE control

feature is not used in this

switch is in B position and

installation.

vice versa. At LIGHT,

STATUS Indicators

The indicator lights are

only the light will illumi-

part of built-in-test equip-

nate when the transpon-

ment. A lit ALT indicator

der replies to mode 4 in-

indicates trouble in the

terrogations. At OUT, the

encoding altimeter. A lit

audio and REPLY light

KIT indicator indicates

monitoring is disabled.

trouble in the computer

MODE 4 TEST-ON-OUT

At ON, the transponder

or the computer is not

Switch

replies to valid mode 4

installed. A lit ANT indi-

interrogations. At OUT,

cator indicates antenna

mode is disabled. At

trouble.

TEST, mode 4 is tested

ANT Switch

Three-position antenna

for proper operation. If

diversity switch labeled

test is valid, TEST GO.

TOP, DIV, and BOT.

Normal position is DIV.

Mode 4 REPLY Light

Illuminates to indicate

When jamming is heavy,

valid mode 4 replies when

TOP or BOT antenna

MODE 4 AUDIO

may be selected.

LIGHT switch is set to

either AUDIO or LIGHT.

IFF Fail Light

The light will illuminate in

TEST GO Light

Illuminates when tran-

sponder responds properly

(Located on the center

MODE 4 when any of the

to TEST position of M-1,

instrument panel)

following occurs:

M-2, M-31A, M-C, or

The computer is in-

MODE 4 TEST-ON-

stalled without a code.

OUT switches.

No reply or improper

TEST/MON NO GO

The light illuminates when

reply is made to a valid

Light

any of the following oc-

interrogation.

curs:

c. A malfunction occurs

MASTER switch is on

in the transponder.

STBY.

Transponder does not

3-64. Normal Operation - Transponder System.

respond to interroga-

The following steps provide transponder system operat-

tion.

ing procedures.

Transponder does not

a. Starting.

respond to TEST posi-

tion of mode switches.

(1)

MASTER control switch - STBY. Red

TEST/MON NO GO light illuminates.

d. Transponder malfunc-

tions.

(2)

Warmup

- 2 minutes.

RAD TEST Switch

At RAD TEST, the tran-

(3)

RAD TEST switch - OUT.

sponder replies to interro-

(4)

IDENT-MIC switch - OUT.

gations from external test

equipment. At OUT, the

(5) AUDIO-LIGHT switch

- OUT. (During

mode 4 operation - As desired.)

3-35

TM 55-1520-240-10

3-65.

AN/ASN-149(V) Global Positioning System

satellites. The aircraft location data calculated by the

(GPS).

GPS is then used to update the INS present position of

a. Description.

The AN/ASN-149 Global

the aircraft.

Positioning System (GPS) shown in Figure 3-17 receives

satellite signals through an antenna located on top of the

b. Controls and Functions. The controls and

aircraft above the cockpit. The GPS then calculates the

functions for the Global Positioning System are

aircraft’s location with respect to the position of the

described in Table 3-5.

Table 3-5. AN/ASN- 149( ) GPS Controls/Indicators and Functions.

Control/Indicator

Function

Line Select

Keys

Lighted. Momentary-contact push-button switches.

Provide three functions:

Enable scratch-pad display to allow operator to enter data on display line

Transfer data from scratch-display to memory.

Select or cancel action displayed on the data entry display line.

Display Screen

Displays operational menus and data entry fields. Contains four display lines with

each line displaying up to 13 characters.

Mode Switch

Four-position rotary switch with pull-to-turn mechanical interlock at OFF and TEST

positions.

OFF

Disables Receivel aLid ilndicaiil-Coiitroller power supplies. Mode switch knob must

be pulled out to rotate to or from OFF position.

INIT (initialize)

Enables initialization (start-up) of the GPS.

NAV (navigation)

Enables GPS navigation functions and sends/receives outputs/receives to/from the

operator and/or other on-board navigation systems.

TEST

Enables GPS self-test. Failures are isolated to assembly level and failure codes

are displayed on the data display. Mode switch knob must be pulled out to rotate to

or from TEST position.

BRT Control

Adjusts data display brightness.

NOTE

Panel lighting brightness is controlled by aircraft dimmer control.

Data Entry Keys

Lighted momentary-contact push-button switches.

Change 6 3-37

TM 55-1520-240-10

Table 3-5. AN/ASN- 149( ) GPS Controls/indicators and Functions - (Continued)

Control/Indicator

Function

USE LTR Key

Lighted momentary-contact push-button switch.

Allows letters to be selected for entry. Also terminates alphabetic data entry.

CLR (clear)

Lighted momentary-contact push-button switch. During Data entry:

One press clears last character entered.

Two presses clears entire display line.

Three presses exits data entry and returns original data display.

WP (Waypoint) Key

Lighted momentary-contact push-button switch.

Allows selection of destination (> ) or waypoint (WP) operation.

MARK Key

Lighted momentary-contact push-button switch.

Enters present position into scratch-pad memory to either freeze position display

or store position information in GPS memory.

Data Select Switch

Ten position rotary switch.

POS (position)

Allows display of resent position coordinates and altitude when D is displayed

on display line 1 or waypoint position coordinates and altitude when WP is

displayed on display line 1.

MSN (mission)

Allows selection of area navigation (RNAV) (stationary waypoint), rendezvous

(moving waypoint) operation. Doppler aiding and GPS outputs to other aircraft

systems. Operates only when > is displayed on display line 1.

OPT (option)

Allows selection of display options.

STAT (status)

Allows display of system status and performance information. Operates only

when > is displayed on display line 1.

VAR-DTM

Allows display of present position magnetic variation and map datum when

(magnetic

> is displayed on display line 1, or waypoint magnetic variation and map datum

variation-map

when WP is displayed on display line 1.

datum)

ERR (error)

Allows display of crosstrack, vertical and track angle errors. Operates only when

> when WP is displayed on display line 1.

3-38 Change 6

TM 55-1520-240-10

Table 3-5. AN/ASN- 149( ) GPS Controls/lndicators and Functions - (Continued)

Control/Indicator

Function

WIND

Allows display of wind speed and wind direction. Computed by GPS using drift

angle, true airspeed and heading. Operates only when> is displayed on

display line 1.

DIS-TG (distance-

Allows display of great circle distance, time to go, bearing and slant range to

time to go)

waypoint.

TRK-GS (track

Allows display of ground track, ground speed of aircraft and time of day when

ground speed)

> is displayed on display line 1, or display of ground track, ground speed and

time of fix of moving waypoint when WP is displayed on display line 1.

DKT-VA (desired

Allows display of desired track and vertical angle to destination when >

track-vertical angle)

is displayed on display line I or desired track and angle to waypoint when WP

is displayed on display line 1.

SLEW ( ) Key

Lighted momentary-contact push-button switch.

Accesses next page of multiple-page displays. Operates when double-headed

arrow ( ) is displayed on right side of display line 1.

Change 6 3-39

TM 55-1520-240-10

c. Operation. The GPS requires map datum. a

If the GPS already has current almanac, the first search

position reference, a time reference, and almanac or

pattern will be based on information contained in the

ephemeris data to perform a normal start-up. Table 3-6.

almanac. For example, if the GPS contains almanac for

If the position reference is not available from internal

PRN3, 9, 12 etc., it will search for PRN3 first then PRN6

memory or external aircraft systems the GPS will request

etc. The time cold start takes under these conditions

position data be entered by the operator. If the almanac

may be considerably less than described above:

data is not available from memory or the data loader,

however, it is still based on satellite visibility. The start-

the GPS will automatically perform a cold-start of the sky

up procedure must be performed prior to using the GPS

to receive satellites. The GPS begins cold-start by

for navigation. Before operating, be sure GPS antenna

searching for PRN6. The search takes up to 6 minutes.

is open to the sky (TM 11-5826-308-12),

If PRN6 signal is not received (tracked), the GPS will

search for PRN 7. If PRN7 is not tracked in 6 minutes,

(1) Preliminary Procedures. Perform the

the GPS will search for PRN

8.This process will

following procedure before attempting GPS start-up.

continue up to PRN32 and start over at PRN1 until a

good satellite is tracked.

Commanded Self-Test - Table 3-8.

Once a good satellite is tracked the AN/ASN149(V)

Selecting units of measurement, coordinate systems,

receive almanac (data). This takes about 13 minutes.

north reference, altitude reference. Table 3-7.

After which the GPS will begin normal start-up operation.

Based on the above description, the time to complete a

cold start is totally dependent on satellite visibility. If

Start-up is being done when PRN6 is overhead and

good. start-up may be completed in less than

minutes.

Table 3-6. AN/ASN-149(V) GPS Start-Up Procedure

Step

Procedure

Display

Set mode switch to INIT.

NOTE

Complete step b if data transfer module receptacle is installed; if

not, go to step c. Transfer data takes 30 seconds. If NAV is

selected before data transfer is finished, the data will be lost.

Ensure data transfer module (if required) is programmed with current data,

then insert data transfer module into data transfer module receptacle.

Change 6 3-41

TM 55-1520-240-10

Table 3-6. AN/ASN-149(V) GPS Stan-Up Procedure - (Continued).

Step

Procedure

Display

NOTE

ENTER POS will be displayed if AN/ASN-

149(V) has no position data in memory. If

ENTER POS is displayed, line select key 3 must

be pressed to return to normal display.

Set data switch to VAR-DTM.

Check display line 1. If WP is displayed, press WP key.

Check map datum on map in use- Look up code for that

map datum in Table 3-16. Compare map datum (DTM)

code displayed on display line 3 with Table 3-16 map

datum code. If displayed DTM code is incorrect, enter

correct DTM code display line 3.

Set data switch to POS.

NOTE

When entering MGRS coordinates, do not press

line select key 2 after entering zone, and line

select key 3 before entering coordinates. MGRS

zone and coordinates are entered like a one

display line entry.

NOTE

Leading zeros must be entered (Example:

91°02'28.3' = 091°02'28.3", 800 = 00800) in steps

g. thru i. if required.

Check latitude/MGRS zone displayed on display line 2. If

displayed position and actual position differ by more

than 60 miles or 100 kilometers, enter correct position

on display line 2.

Check longitude/MGRS coordinates displayed on display

line 3. If displayed position and actual position differ by

more than 60 miles or 100 kilometers, enter correct

position on display line 3.

3-42 Change 6

TM 55-1520-240-10

Table 3-6. AN/ASN-149(V) GPS Start-Up Procedure - (Continued).

Step

Procedure

Display

Check altitude on display line 4. If displayed altitude and

actual altitude differ by more than 656 feet (FT) or 200

meters (M), enter correct altitude on display line 4.

Set data switch to TRK-GS.

Press slew key.

NOTE

Time is displayed in coordinated universal

(Zulu) time (24 hour clock).

Leading zeros must be entered (Example: 1:09:08

= 01:09-.08) in step I if required. Leading zeros

will not be erased when entry is complete.

Check Zulu time displayed on display line 2. If displayed

Zulu time differs from actual Zulu time by more than 1

minute, enter correct Zulu time on display line 2.

NOTE

Day of year is Julian date.

Leading zeros must be entered (example: 3 =

003, 33 - 033) in step m, if required. Leading

zeros will not be erased when entry is complete.

Check year (YR) and day of year (DOY) on display line 4.

If YR and DOY and actual YR and DOY differ, enter

actual YR and DOY on display line 4.

Set data select switch to MSN.

Check display line 3; if *DOP ONLY displayed, press line

select key 3.

Check display line 4; if *GPS ONLY displayed, press line

select key 4.

Press slew key.

Change 6 3-43

TM 55-1520-240-10

Table 3-6. AN/ASN-149(V) GPS Start-Up Procedure - (Continued).

Step

Procedure

Display

Check display line 4; if - BARO is displayed, press line

select key 4.

NOTE

After NAV is selected, time and position

initialization inputs cannot be changed.

Remove data transfer module from data transfer module

receptacle if installed.

NOTE

Complete steps t thru y if AN/ASN-149(V) is to

supply time correction information to precise

time and time interval (PTTI) equipment. If

not, go to step z.

Rotate data switch to OPT.

Press slew key until CW is displayed on display line L

Enter 12 on display line 1.

NOTE

Leading zeros must be entered (example: 5 =

005, 10 = 010) in steps w and y, if required.

Leading zeros will be erased when data entry is

complete.

Check LI path delay on display line 2. If displayed LI

path delay and actual LI path delay differ, enter actual

LI path delay in nanoseconds on display line 2.

3-44 Change 6

TECHNICAL MANUAL MAINTENANCE MANUAL FOR ARMY CH-47D HELICOPTER (1992) - page 6