EA-18G. FLIGHT MANUAL (2008)

A1-E18GA-NFM-000

Figure 24-7. NAVCK Page

24.2.3.5 Gyro Recovery. A gyro recovery is actually an AHRS attitude only INS in which reliable

INS attitude data is recovered. If the GPS is functional, the GPS will initialize and acquire satellites.

Select AUTO or INS with the ATT switch and maintain straight and level, unaccelerated flight. Select

OFF for 20 seconds prior to selecting GYRO. As the platform levels, the INS ATT caution clears and

standby attitude reference indicator data on the HUD is replaced with INS attitude data. A flashing

velocity vector replaces the waterline symbol until GPS velocity data is valid if operational. If takeoff

occurs before an adequate alignment is complete, GYRO mode is available.

24.2.4 ANAV BIT. The ANAV (INS and GPS) uses both periodic and initiated built−in test (BIT).

ANAV BIT status is displayed on the BIT page next to the INS and GPS legends. Periodic BIT

monitors essential parameters within the system and provides in−flight, shipboard, and ground failure

detection and isolation. Initiated BIT is performed on the ground and accomplishes that portion of the

failure detection and isolation capability which periodic BIT is unable to do. Initiated ANAV BIT can

be performed by selecting the INS/GPS option on the NAV sublevel of the BIT page.

24.2.5 NAVCK Page. The NAVCK page allows analysis of INS/GPS/FCC air data function

reliability (figure 24−7). The page is displayed by selecting the NAV CK option on the HSI A/C DATA

page. The velocity check more readily indicates an INS vertical or horizontal velocity problem. INS,

GPS and FCC air data function velocities are periodically compared and when an excessive

disagreement is sensed, the NAV VVEL or NAV HVEL cautions are set.

The top portion of the page consists of INS, GPS and FCC air data function (ADC) velocities. The

bottom portion consists of wind velocities, best available MC groundspeed (if valid) and best available

MC true airspeed (if not zero). INS, GPS and ADC velocity components are displayed even if invalid.

If INS, GPS or ADC data is invalid, a # is displayed to the right of the invalid data along with #

INVALID at the bottom of the page. If wind velocity is estimated, an * (asterisk) is displayed to the

right of the wind velocity components along with *EST at the bottom of the page.

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24.2.6 GPS Page. The GPS page displays current GPS status (see figure 24-3). The page is displayed

by selecting the GPS option on the SUPT MENU.

The GPS operating mode is displayed at the top of the page (GPS − XXXX) with possible modes

of NAV, INIT, NOT RDY, or TEST (see 24.2.2 for a description of operating modes). When the GPS

is not in TEST, the NAV and INIT options are available. The use of these two options is not

recommended.

The GPS Figure of Merit (FOM) is an indication of the estimated GPS position accuracy with a

value from 1 to 9, with 1 being the best and 9 the worst. The following table shows the corresponding

estimated accuracy.

FOM Value

Expected Position Error* (Meters)

Less than or equal to 25

Greater than 25 up to 50

Greater than 50 up to 75

Greater than 75 up to 100

Greater than 100 up to 200

Greater than 200 up to 500

Greater than 500 up to 1000

Greater than 1000 up to 5000

Greater than 5000

* 3−dimensional, 1−sigma

The SAT STATUS is an indication of satellite signal integrity. Possible indications are GOOD,

MARGINAL, and JAMMED. An overall State 5 indicates GOOD, State 3 indicates MARGINAL, and

if not in State 5 and not in State 3, JAMMED is indicated.

The GPS current position is displayed along with the GPS’s Horizontal and Vertical Estimated

Errors (HERR and VERR) in feet and GPS TIME.

Up to 4 individual satellite channel states are displayed. If the number of satellites in State 5 are

greater than or equal to 4, all 4 positions will indicate State 5. If less than 4 satellites are indicating

State 5, the corresponding number of positions will indicate State 5 and the remaining positions will

indicate State 3 or be blank.

The bottom of the page displays the crypto key status. Up to seven crypto key status messages can

be displayed. Three of the status messages are mutually exclusive: VERIFIED, UNVERIFIED, and

INCORRECT. The other six messages are displayed when reported by the GPS: GUV USER (group

unique variables), KEY FAIL (key failed parity), INSUFF KEY (insufficient keys), ERASE FAIL

(erase failure), 2 HR ALERT (2 hour alert), and VALID ENTRY (receiver contains keys).

24.2.7 INS Knob. The INS knob is located on the right hand console SNSR panel and has positions

of OFF, CV, GND, NAV, IFA, GYRO, GB, and TEST.

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OFF

Removes power from ANAV (INS and GPS).

Commands the INS carrier alignment mode. GPS initializes and acquires satellites.

GND Commands the INS ground alignment mode. GPS initializes and acquires satellites.

NAV Commands the INS to unaided navigation mode (POS/INS) which enables the MC to use un-

aided INS or GPS data to provide navigation steering.

IFA

Commands the INS in−flight alignment mode. Also commands the INS into aided navigation

mode (POS/AINS) after alignment complete.

GYRO Commands the AHRS mode. GPS initializes and acquires satellites.

Commands the INS to CV or GND alignment mode indefinitely. GPS initializes and acquires

satellites.

TEST Enables the INS and GPS to perform an initiated BIT upon command from the MC.

24.2.8

INS/GPS Related Cautions and Advisories. The following INS/GPS related cautions and

advisories are described in the Warning/Caution/Advisory Displays in Part V:

• GPS DEGD caution

• INS ATT caution

• INS DEGD caution

• NAV FAIL caution

• NAV HVEL caution

• NAV VVEL caution

• POS/ADC caution

• POS ERROR caution

• ALGN (x’d out) advisory

• GPS advisory

• GPSMP advisory

• NODOV advisory

• NOSEC advisory

• P/INS advisory

• PCODE advisory

• VVEL advisory

• YCODE advisory

24.2.9 Waypoints, Offset Aimpoints (OAP), and Offsets. A waypoint is a geographical point for

which latitude, longitude, and elevation are stored in the MC. An OAP is a waypoint which has an

offset associated with it. An offset is a point defined by bearing and range from the OAP along with

elevation of the point (offset).

Mission data such as waypoints and offsets may be entered using the Data Transfer Equipment

(DTE) and the mission initialization display or manually.

24.2.9.1 Waypoint/Offset Aimpoint Programming. Waypoint/OAP data is entered by selecting the

DATA option on the waypoint data top level display. The waypoint data display is automatically

initialized with WYPT boxed. This display shows the current waypoint/OAP data: waypoint lat/long

position, UTM Grid coordinates, and elevation; offset range, GRID, bearing, and elevation (if

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applicable). Waypoint/OAP data is entered by selecting an up/down arrow to select the desired

waypoint/OAP and the UFC option to initialize the UFCD for waypoint/OAP data entry. On the

UFCD the following selections complete the selection: POSN option to enter lat/long data, ELEV

option to enter elevation data, and O/S option to enter offset data (offset range, bearing, UTM grid

coordinates and elevation). Offset data is in relation to the offset aimpoint. Waypoint/OAP data is

entered through the UFCD keypad, with a maximum of 60 waypoints (0 to 59) available for

programming. See figure 24-8, sheets 1 and 2.

Waypoint data can also be entered using the map slew method by selecting WYPT on the DATA

option display, and actuating the SLEW button. Pressing the TDC and slewing the map to the desired

lat/long position under the waypoint symbol locates the point.

NOTE

Lat/long and elevation data on the MPCD reflect the current map

position under the waypoint symbol as the map is being slewed.

Upon release of the TDC the current waypoint data is entered for the map position under the

waypoint symbol. Selecting the next waypoint number as required (using the waypoint increment/

decrement option buttons) allows further waypoint data entry.

Another map slew method is to select WYPT on the DATA option display, actuating the SLEW

button, and pressing and holding the TDC to slew the map to the desired lat/long position under the

waypoint symbol. This position is entered by selecting another waypoint (using the waypoint

increment/decrement option buttons). Continuing to hold the TDC, the map is slewed as required, and

the next waypoint is selected for further waypoint data entry.

Offset aimpoints may also be entered using the map slew method; however, the associated offset

must be entered through the UFCD.

24.2.10.1.1 GPS Waypoint Programming. Aircraft with GPS can utilize the GPS to store up to 200

waypoints. GPS points are loaded into the GPS from the memory unit. GPS points can be displayed

and/or transferred into the MC waypoint data base using the HSI/DATA/GPS display. A GPS point

can be transferred into any MC waypoint by pressing the XFER option on the GPS display. When GPS

option is selected the first 24 GPS points are displayed in alphanumeric order. Selection of points to

load is accomplished by the right and down arrows and page selection arrows. Repeated selection of

these arrows causes the cursor to wrap around. It may take as long as three seconds to retrieve selected

position data and display it on the GPS display. See figure 24-8. GPS waypoints are transferred to the

MC by selecting the desired waypoint number with the up/down arrows on the HSI/DATA/GPS

sublevel, moving the cursor down/right and/or page up/down to the desired waypoint ID code, and

pressing XFER. The GPS LAT/LONG, GPS altitude, and current ID code displays are blanked and

the XFER option is removed. The selected ID code is displayed in the ‘‘Current ID’’ position indicating

that waypoint is requested. After approximately 3 seconds, the requested GPS LAT/LONG and GPS

altitude is displayed and the XFER option is returned for transfer selection. If a GPS ID code is

requested and is not available, the selected ID code is displayed with a line through it. Once a GPS

waypoint has been transferred from the GPS to the MC it becomes an MC waypoint. The waypoint ID

code is retained and is displayed on the top level HSI and HSI/DATA/WYPT formats when the

waypoint is selected as the current waypoint.

24.2.10.1.2 UTM Data Entry. Data for all waypoints and OAPs may be entered as universal

transverse mercator (UTM) coordinates. See figure 24-9. UTM grid coordinates are defined by a

spheroid, grid zone designation, square identification, and easting/northing. Grid zone designation

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Figure 24-8. GPS Waypoint Display

divides the world area between N84° and S80° into 100 km squares. At power up with WonW the MC

initializes waypoint elevation, O/S range and elevation, and TACAN elevation in FEET, and O/S

bearing to TRUE. UTM data for waypoints are entered by performing the following:

1. Select DATA/WYPT on the HSI top level display.

2. Select the desired spheroid by selecting the spheroid option.

3. Select UFC on the HSI. The first cockpit to select UFC has control of grid data entry and has the

GRID display on the RDDI.

4. Select GRID on the UFCD. The MC determines the grid zone designation and 100 km square ID

of the reference position and constructs a five by five Square Identification Grid (SIG) centered

about the reference position and displayed on the RDDI. Reference position is either the A/C

present position or the referenced waypoint position (REF WP Boxed).

5. Slew the acquisition cursor into the desired square, depress and release the TDC.

6. On the UFCD enter the six digit easting/northing and press O/S. Leading zeros must be input for

easting/northing. The UTM coordinates are displayed on the HSI under the lat/long provided the

latitude is within the N84° to S80° limits.

UTM data for O/S are entered by performing the following:

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7. Select DATA/WYPT on the HSI top level display.

8. Select UFC on the HSI.

9. Select O/S on the UFCD.

10. Select Grid on the UFCD.

11. Slew the HOTAS cursor into the desired square, depress and release the TDC.

12. Enter O/S easting/northing in the UFCD.

The MC converts the UTM Grid coordinates to latitude/ longitude and then to range and bearing.

O/S coordinates more than 400,000 feet from the OAP cause the UTM coordinates to flash in the O/S

grid field on the HSI. The UTM coordinate is displayed in the O/S field on the HSI.

SIG square blanking must be checked any time the SIG is built. If the latitude is out of UTM range

(above N84°or below S80°) the entire row is blanked. At certain latitudes, due to the convergence of

the earth, individual squares are blank.

Grid shift options are provided to view and select grid squares in the eight adjacent grid squares

whenever the A/C or Waypoint symbol is in the center square of the SIG and the adjacent SIGs exist.

See figure 24-9. N, S, E, W, SE, SW, NE, or NW can be selected by pressing the grid shift options on

the HSI, or by pressing and releasing the TDC when the HOTAS cursor is over a grid shift push button

legend. The MC determines a new center position about which to construct a new SIG. Selecting the

A/C or waypoint symbol returns the SIG to the original position.

Units can be input as FEET or MTRS for elevation; FEET, MTRS, NM, or YARD for range. The

MC tests that all bearing, range and elevation data input through the UFCD are in the valid range.

Unit

Valid Range

Easting/Northing

000000 - 999999

Bearing

0 - 359° 59’ 59’’

Offset

0 - 400,000 FT

0 - 122,000 MTRS

0 - 66 NM

0 - 133,000 YDS

When data is outside the valid range, the MC causes the word ERROR to flash in the UFCD

scratchpad and requires the data to be reinput.

24.2.10.2 Target (TGT) Programming. A target must be entered in a waypoint/OAP sequence so the

MC can calculate the groundspeed required to arrive on target at the appropriate time. Only one

waypoint/OAP can be designated as a target for all three sequences. A waypoint/OAP is identified as

a target on the waypoint data sublevel display by an inverted triangle above the waypoint/OAP number

in the waypoint/OAP sequence. At power up with WonW the previous target waypoint/OAP is cleared.

A waypoint/OAP as a target in a waypoint/OAP sequence is designated the DATA option on the HSI

top level display, the SEQUFC option on the waypoint data sublevel display to initialize the UFCD.

The waypoint/OAP number is entered on the UFCD keypad and the TGT option selected. The target

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waypoint/OAP is undesignated by either entering the target waypoint/OAP a second time or entering

an invalid waypoint/OAP. See figure 24-9.

24.2.10.3 Time On Target (TOT) Programming. TOT pertains to the programmed target waypoint/

OAP, and is relative to the programmed ZTOD (zulu time of day). ZTOD must be programmed before

TOT can be entered. TOT is programmed from 00:00:00 to 23:59:59 and is displayed on the waypoint

data sublevel display.

TOT is entered by selecting the DATA option on the HSI top level display, selecting the SEQUFC

option on the waypoint data sublevel display to initialize the UFCD, entering the desired TOT value

on the UFCD keypad, and selecting the TOT option. See figure 24-9.

24.2.10.4 Groundspeed Programming. Groundspeed pertains to the desired groundspeed for the

final leg to the target waypoint in the sequence. Groundspeed values up to 999 knots may be entered.

Groundspeed is entered by selecting the DATA option on the HSI top level display, selecting the

SEQUFC option on the waypoint data sublevel display to initialize the UFCD, entering the desired

GSPD value on the UFCD keypad, and selecting the GSPD option. See figure 24-9.

24.2.10.5 Waypoint/OAP Sequence Programming. A total of three waypoint/OAP sequences are

available for waypoint/OAP sequence programming and a maximum of 15 waypoint/OAPs may be

programmed in each sequence. These sequences are used for AUTO sequential steering and time on

target groundspeed cuing.

The waypoint data sublevel display on the HSI display must be used with the UFCD to allow the

pilot to program a waypoint/OAP sequence. The SEQ # option on the lower right corner of the display

indicates the waypoint/OAP sequence in use and initializes to the sequence selected on the HSI top

level display. This option selects the sequence to be programmed (SEQ1, SEQ2, SEQ3, or SEQL).

Selecting the SEQUFC option, on the lower left corner of the display, initializes the UFCD for

waypoint sequence programming. A waypoint/OAP cannot appear more than once in sequence but a

waypoint/OAP may be entered in more than one sequence. Mark points cannot be programmed in a

sequence. Each waypoint/OAP entered is placed to the right of the last waypoint/OAP in the sequence.

15 waypoints/OAPs are programmed, the first waypoint in that sequence is deleted and the

remaining waypoints/OAPs move to the left one space. Data for the current waypoint/OAP inserted/

deleted in the sequence is provided on the waypoint data level display.

A new waypoint/OAP sequence is programmed by selecting:

1. The waypoint data sublevel display using the DATA option

2. The desired sequence route number using the SEQ # option

3. The SEQUFC option to initialize the UFCD for sequence programming

4. The desired waypoint/OAP number via the UFCD keypad

5. The INSERT option on the UFCD

6. Repeat steps 4 through 5 for each waypoint/OAP in the sequence. See figure 24-9.

Waypoints/OAP are inserted into an existing sequence by selecting:

1. The waypoint data sublevel display using the DATA option

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2. The desired sequence route number using the SEQ # option

3. The SEQUFC option to initialize the UFCD for programming

4. The number of the waypoint/OAP to the left of the desired insertion point via UFCD keypad

5. The INSERT option on the UFCD keypad

6. Number of the waypoint/OAP to be inserted via the UFCD keypad

7. The INSERT option via the UFCD keypad

Waypoints are deleted from a sequence by selecting:

1. The waypoint data sublevel display using the DATA option, the desired sequence route number

using the SEQ # option

2. The SEQUFC option to initialize the UFCD for programming

3. The number of the waypoint/OAP to be deleted via the UFCD keypad

4. The DELETE option via the UFCD keypad

When a waypoint/OAP is deleted from a sequence all waypoints/OAPs to the right of the deleted

waypoint/OAP shift left one space.

24.2.11 Aircraft (A/C) Programming. Aircraft data is entered by selecting the DATA option on the

HSI top level display and the A/C option on the waypoint data sublevel display to bring up the A/C

data sublevel display. This display shows the current aircraft data: latitude/longitude position, wind

speed, wind direction, magnetic variation, and magnetic/true heading selection. Aircraft data is

entered by selecting the UFC option to initialize the UFCD keypad for aircraft data entry, selecting the

LATLN DCML or SEC option and then POSN option to enter lat/long data, the WSPD option to enter

wind speed data, the WDIR option to enter wind direction, and MVAR to enter magnetic variation

(degrees/minutes beginning with E or W). The TAWS/GPWS option allows selection/deselection of

TAWS and GPWS. See figure 24-9, sheet 3.

NOTE

Entering a MVAR value without selecting the MVAR option will result

in changing the aircraft position and may result in large INS position

keeping errors.

24.2.11.1 Latitude/Longitude Display/Entry. Latitude and longitude are displayed either as

Degrees/ Minutes/ Ten Thousandths of minutes (LATLN DCML) or Degrees/Minutes/Seconds/

Hundredths of seconds (LATLN SEC). Actuating the LATLN XXXX option toggles between the

selection of LATLN DCML and LATLN SEC. The selected LATLN format is reflected on all displays

and UFCD formats throughout the cockpit. DCML is the cold start default.

24.2.11.1A True/Magnetic Heading Selection. Heading indications that appear on the HUD and

HSI display can be referenced to either true north or magnetic north. The capability to select a true

north heading is useful in extreme northern operations. With true north heading selected, the HSI

display, A/A and A/G radar displays, Link 4 display, and the HUD all are referenced to true north. The

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true north indication on the HUD is a T displayed below the current heading. True north indications

on the HSI display consist of TRUE displayed below the current heading readout and a T displayed

below the lubber line. The true heading indications on the HSI display also appear on the Link 4

display. No indications of true north selection appear on the A/A or A/G radar display. Since aircraft

magnetic variation is used as the best available magnetic variation source, the heading reference should

not be changed when navigating a selected course.

With true heading selected, TACAN symbology is also referenced to true north if the TACAN

station is in the TACAN data table. If the TACAN station is not in the TACAN data table, magnetic

heading is used. There is no indication when magnetic heading is selected. When INS true heading

becomes invalid, magnetic heading is used. If MC1 fails, heading selection is not available. At power up

with WonW the system initializes with magnetic heading selected. The reference heading is selected by

selecting DATA on the HSI display and the A/C option to access the A/C data sublevel display.

Actuating the HDG XXX option toggles between the selection of HDG TRUE and HDG MAG.

24.2.11.2 Barometric (BARO)/Radar Low Altitude Warning Programming. The BARO/RADAR

altitude warning can be set up to a maximum of 25,000 feet for BARO and 5,000 feet for RADAR.

Setting the RADAR at a value greater than 5,000 feet results in 5,000 feet being used. Passing through

the BARO/RADAR programmed altitude from above results in the ALTITUDE voice alert. Setting

the BARO/RADAR altitude warning to 0 feet disables this function. At power up with WonW, RADAR

altitude warning initializes to 5,000 feet and BARO altitude warning initializes to 10,000 feet.

Set the BARO/RADAR low altitude warning function by selecting the DATA option on the HSI top

level display selecting the A/C option to bring up the A/C data sublevel display. The BARO/RADAR

altitude functions are located on the lower left corner of the display. Selecting BARO or RADAR

initializes the UFCD for altitude entry. Enter the desired altitude through the UFCD keypad and press

the BARO or RADAR option. The entered altitude appears on the A/C data sublevel display below

BARO/RADAR as appropriate. See figure 24-9, sheet 3.

24.2.11.3 Zulu Time of Day (ZTOD). The FIRAMS Real Time Clock (RTC) is used to keep ZTOD.

The only time ZTOD needs to be set is if the FIRAMS RTC failed power up BIT. In this case the MC

internal counter would be used and requires the MC internal clock to be set. ZTOD is displayed on the

HUD and HSI display and is needed to calculate MC required groundspeed and TOT.

Enter ZTOD by selecting the TIMEUFC option on the HSI top level display to initialize the UFCD

for ZTOD programming. Enter 6 digits (HHMMSS) on the UFCD keypad, and then select the ZTOD

option on the UFCD. At first selection of ZTOD, it is displayed on the HUD and HSI display. ZTOD

is displayed on the lower left corner of the HUD and HSI display. If time is displayed on the HUD, the

respective option has ″*HUD″ displayed below it. ZTOD is not displayed on the HUD when either the

ET or CD is selected for display. See figure 24-9, sheet 4.

24.2.11.4 Elapsed Time (ET). ET starts incrementing in minutes and seconds from 00:00 to 59:59.

When 59:59 is reached ET resets and begins incrementing again from 00:00. ET is displayed on the

lower left corner of the HUD and on the lower right corner of the HSI display. ET is not displayed on

the HUD or HSI display when either ZTOD, LTOD or CD is selected.

Activate ET by selecting the TIMEUFC option on the HSI top level display initializes the UFCD for

ET selection. Selecting the ET option on the UFCD displays ET 00:00 on the HUD and HSI display.

See figure 24-9, sheet 4.

24.2.11.5 Countdown Time (CD). CD starts decrementing in minutes and seconds from a default

value of 06:00. When 00:00 is reached, the CD timer is removed from the HUD and HSI displays. CD

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Figure 24-10. Position Keeping

is displayed on the lower left corner of the HUD and on the lower right corner of the MPCD. CD is not

displayed on the HUD or HSI when either ZTOD, LTOD or ET selected. The CD timer initializes to

the default value at power up with WonW.

Activate CD by selecting the TIMEUFC option on the HSI top level display to initialize the UFCD

for CD selection. Selecting the CD option on the UFCD displays CD 06:00 on the HUD and HSI

display. See figure 24-9, sheet 4.

The CD default value can also be reset by entering in a value between 00:00 and 59:59 by selecting

the TIMEUFC option on the HSI top level display to initialize the UFCD for CD programming,

entering in the reset value through the UFCD keypad, and pressing the CD option. The reset value

must be less than or equal to 59:59 so that when the CD option is pressed the CD timer begins to

decrement. If the reset value is greater than 59:59, selection of the CD option sets the reset value to

59:59 and freezes the CD timer.

24.2.11.6 Local Time Of Day (LTOD) Programming. LTOD is displayed on the HUD and HSI

display. Set LTOD by selecting the TIMEUFC option on the HSI top level display initializes the

UFCD for LTOD programming. Enter LTOD (HHMMSS) on the UFCD keypad, and select the LTOD

option. The LTOD option is displayed if the FIRAMS passes power up BIT. See figure 24-9, sheet 4.

24.2.11.7 Date (DATE). Set the date by selecting the TIMEUFC option on the HSI top level display

initializes the UFCD for date programming. Enter the date in MDDYY format on the scratchpad , and

select the DATE option. See figure 24-9.

24.2.11.8 Time Zone. The time zone is set by first entering ZTOD followed by LTOD. The MC uses

the difference between these values as the current time zone. Any future changes to ZTOD

automatically changes LTOD based on the current time zone. Any future changes to LTOD resets the

time zone.

24.2.12 Position Keeping. Selection of the POS/XXX option on the HSI top display provides the

position keeping option display, see figure 24-10. This display allows in-flight selection of POS/AINS,

POS/ADC, POS/GPS, POS/INS, POS/MIDS (if installed), or POS/TCN as the position keeping

source. Selecting one of these options returns the HSI top level display with the appropriate position

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keeping source selected. INS position keeping is automatically selected during ground operations when

INS data is valid. Should the INS fail, the mission computer automatically begins FCC air data

position keeping from the last valid INS position; however, it is unreliable.

AINS and GPS position keeping are not available unless good GPS data is available. GPS data is

good when the GPS vertical error (GPS VERR) and GPS estimated horizontal error (GPS HERR), as

shown on the aircraft data format, are each less than 100 feet. AINS position keeping is selected by

placing the INS mode switch in the IFA position. Automatic position keeping reversion with a

hierarchy of AINS, INS, GPS , MIDS (if installed) and FCC air data is provided in case of an INS

and/or GPS failure. TACAN position keeping provides distance data from one of the previously stored

TACAN stations. The desired TACAN station is selected on the UFCD. See TACAN position keeping

this section.

MIDS Precise Participant Location and Identification (PPLI) altitude

shall not be used as an altitude reference for determining safe separation

of aircraft or terrain avoidance.

MIDS position keeping is the default position keeping mode if GPS and

INS are not available. Because MIDS alone is unreliable as a position

keeping source, POS/ADC should be selected if INS and GPS fail or

become unreliable as position keeping sources. Aircrew is unable to enter

data parameters required for an INS or radar IFA if POS/MIDS is the

position keeping source.

24.2.13 Position Updating. Selecting the UPDT (update) option on the HSI top level display

provides the update sublevel display, see figure 24-11. This display allows in-flight selection of VEL

(velocity), TCN (TACAN), GPS, DSG (designate), AUTO (automatic), and MAP as the update

options. These options provide position/velocity updating to the INS/ADC during NAV or IFA modes.

All updates must be performed while in the NAV or A/G master modes, unless noted otherwise. TCN

position updating is described in the TACAN section, and VEL updating is described in NTRP

3-22.2-EA-18G (EA-18G Classified Manual).

NOTE

The update option is not available in AINS position keeping.

After an update is performed, the CANCEL option is displayed on the HSI UPDATE option display.

Pressing the CANCEL option cancels the previous update and removes the CANCEL option. The INS

updates the aircraft position using the last accepted position update. The CANCEL option is also

removed on touchdown or when present position is changed using the UFCD.

24.2.13.1 Designation (DSG) Update. A designation update is performed by pressing the UPDT

option on the HSI top level display. Selecting the DSG option on the UPDT sublevel display.

Designating a waypoint/OAP with a sensor (radar, or LDT), a HUD designation, or an overfly

designation. The DSG option may be selected before or after waypoint designation. When the

designation has been performed and DSG option selected, sensor ranging components to the target are

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added to the previously entered waypoint position to give an aircraft computed position. The

difference between the computed aircraft position and the onboard aircraft position produces the

position error readout in bearing and range on the ACPT/REJ display. Selecting the ACPT option

accepts the position update and returns the HSI top level display. Selecting the REJ option rejects the

update and returns the HSI top display. A DSG update may be performed in the A/A master mode if

the designation was performed in A/G prior to entering A/A. The selection of UPDT/DSG suspends

auto sequential steering and disengages coupled steering.

24.2.13.2 Post-flight Update. The INS post-flight update collects terminal INS maintenance data.

The post flight update is performed using the overfly designation update method. The INS determines

the overfly designation update is a post flight update using the WonW transition. The aircraft must be

completely stopped and the parking brake engaged to prevent erroneous terminal velocity data. The

post flight update is not performed onboard ship.

The INS post flight update may be performed when the parking brake is set and the aircraft is

within 600 feet of the appropriate waypoint entered in the system (the update waypoint need not be

waypoint 0). If the waypoint position is known but not programmed in the system, the position may be

entered and used for the update. If no waypoints are available, no update should be attempted.

24.2.13.3 MAP Update. A MAP update is performed by selecting the UPDT option on the HSI top

level display, designating a waypoint/OAP with a sensor (radar, or LDT), a HUD designation or an

overfly designation and selecting the MAP option on the update sublevel display. When this is done the

word SLEW appears in the upper right corner of the HSI and the TDC is automatically assigned to the

MPCD (for map slewing). The map can now be slewed so the target on the map is under the designation

symbol (diamond). The difference between the target position and the designated position produces

the position error readout in bearing and range on the ACPT/REJ display. Selecting the ACPT option

accepts the position update and returns the HSI top level display. Selecting the REJ option rejects the

position update and returns the HSI top level display. The MAP option is not available if a map is not

installed.

24.2.13.4 AUTO Update. An AUTO update is performed by selecting the UPDT option on the HSI

top level display and selecting the AUTO option on the UPDT sublevel display. When this is done the

AUTO option is boxed and the VEL, TCN, DSG and MAP options are removed. The pilot must assign

the TDC to the MPCD, overfly the waypoint/OAP and press the TDC while over the waypoint/OAP.

The MC enters the waypoint/OAP as the aircraft present position and the HSI top level display is

returned. The next waypoint in succession becomes designated or, in the case of an OAP, the offset

becomes designated. There is no ACPT/REJ display in the AUTO update mode.

24.2.14 NAV/TAC Bank Limit Options. Bank angle control 1 (BAC1) is engaged when any coupled

steering mode is engaged. BAC1 provides aircraft steering commands and limits; and maintains the

aircraft on course to the selected waypoint(s), offset aim point(s), or TACAN station. BAC1 also

provides steering to capture and hold a course line through the current WYPT, OAP, or TACAN

station. The maximum bank limit (BLIM) is selectable on the A/C data display. TAC BLIM is used for

tactical missions and limits the bank angle between ±30° and ±60° with a bank rate between 10° and

30° per second based on airspeed. NAV BLIM is used for general navigation and sets bank angle to a

fixed ±30° limit with a maximum bank angle rate of 10° per second.

24.2.15 Steering. Types of waypoint/OAP steering described include direct great circle, course line,

auto sequential, and target.

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24.2.15.1 Waypoint/OAP Direct Great Circle Steering. Direct great circle steering is available in all

master modes and is selected/deselected by actuating the WYPT/OAP option on the HSI. Selecting

waypoint/OAP steering deselects ILS, D/L, and TACAN steering. When steering is selected, the option

is boxed and direct great circle steering is provided on the HUD as shown in figure 24-12. To follow a

direct great circle path to the waypoint/OAP, the aircraft is turned so that the command heading

steering pointer under the heading scale is centered in the heading caret. The steering provided by the

steering pointer is corrected for wind drift. When the steering pointer is within ±5° of the caret as

measured on the heading scale, it provides a direct indication of steering error. Between ±5° and the

ends of the heading scale (±15°), the steering pointer moves nonlinearly so that it is at the end of the

heading scale when the steering error is 30°. The steering pointer is displayed at the end of the heading

scale when the steering error is greater than 30°, the steering pointer begins to move to provide

anticipation for rolling out of the turn, and the actual steering error is indicated when within 5°.

Waypoint/OAP range, identification, and number are displayed on the lower right side of the HUD.

On the HSI, the position of the waypoint/OAP is indicated by the waypoint/OAP symbol as shown

on figure 24-12. If the selected steer to point is an OAP, the position of the offset is indicated by the

offset symbol. Bearing to the waypoint/OAP is indicated by the pointer inside the compass rose. The

waypoint/OAP symbol and pointer are displayed whether or not direct great circle steering is selected.

They provide a navigation situation display only. Steering (corrected for drift) is provided only on the

HUD. A digital readout of bearing and range to the waypoint/OAP is provided on the upper

right corner of the MPCD. Time to go to the waypoint/OAP in minutes and seconds, based on range

and groundspeed, is provided under the bearing and range readout.

24.2.15.2 Waypoint/OAP Course Line Steering. Course line steering is used when it is desired to fly

a selected course to the waypoint/OAP. Course line steering is selected by selecting direct great circle

steering and actuating the course select switch. When the course select switch is actuated, the course

line appears through the waypoint/OAP symbol as shown in figure 24-13, sheet 1. The course line

rotates clockwise while the course select switch is held to the right and counterclockwise while it is held

to the left. A digital readout of the selected course is provided in the lower right corner of the MPCD.

When the waypoint/OAP symbol is beyond the range of the selected MPCD scale, the waypoint/OAP

symbol is limited at the inside of the compass rose coincident with the head of the pointer and the

course line rotates about the head of the pointer. It does not then overfly its correct position on the

map; but, does correctly indicate to which side of the aircraft the course lies, and the intercept angle

is correctly represented.

When a course line is selected, steering on the HUD is displayed. The arrow provides a horizontal

situation indication relative to the velocity vector. As shown, the aircraft is to the right of the selected

course, but is converging toward it. Two dots are displayed on the side of the velocity vector toward the

steering arrow and in a line perpendicular to it. The outermost dot represents full scale deflection of

the arrow (8°) and the innermost dot indicates half scale deflection (4°). If the arrow moves to the other

side of the velocity vector, the dots appear on that side. The dots are not displayed when within

approximately 1.25° of being on course. Figure 24-13, sheet 2 shows an example of the HUD steering

arrow display as the aircraft crosses a course line. The HUD situation arrow display is available only

in NAV master mode, although waypoint/OAP steering can be selected and the course arrow can be

displayed and used on the MPCD in any master mode. Only waypoint/OAP direct great circle steering

is available on the HUD when designated. Course line steering can be deselected either by deselecting

waypoint/OAP direct great circle steering or by selecting a new waypoint/OAP, initializing direct great

circle steering.

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Figure 24-13. Waypoint/OAP Course Line Steering (Sheet 2 of 2)

24.2.15.3 Coupled Waypoint/OAP Steering. When waypoint steering is coupled, CPL WYPT is

displayed on the HUD and HSI display, and a CPLD advisory appears on the DDI. The aircraft steers

to intercept the desired course line, or flies to the point if no course line is selected. Bank angle is

limited by NAV or TAC bank limit option as selected on the A/C sublevel display and described in

chapter 2. As the aircraft gets close to the desired course, the bank angle is reduced to maintain the

aircraft on the desired course. If course line steering is not selected, when the aircraft reaches the

waypoint or offset aim point (OAP) WYPT steering uncouples and reverts to HDG hold. If course line

steering is selected, the aircraft remains coupled and flies an outbound radial. RALT or BALT,

whichever is selected, remains engaged when the aircraft passes the waypoint. If a ground point is

designated, WYPT steering does not couple, or uncouples if previously coupled. If waypoint steering

does not engage or disengages without being commanded, an AUTOPILOT caution is displayed on the

DDI, and CPL WYPT flashes for 10 seconds on the HUD and HSI displays. The caution can be cleared

with the paddle switch.

24.2.15.4 AUTO Sequential Steering. Before AUTO sequential steering can be selected a waypoint/

OAP sequence must be programmed.

AUTO sequential steering is selected by actuating the AUTO option (AUTO boxed) on the MPCD.

When selected, other steering modes not compatible with AUTO sequential are deselected.

With AUTO sequential steering engaged, great circle steering is provided to the first waypoint/OAP

in the selected sequence, see figure 24-14. When range to the steer to waypoint/OAP is less than 5 NM

and bearing is greater than 90°, the next waypoint/OAP in the sequence is automatically selected.

Great circle steering is automatically provided for each new steer to waypoint/OAP in the sequence.

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During AUTO sequential steering course line steering is available but course line is deselected when

the steer to waypoint/OAP is within the range and bearing mentioned above. The waypoint/OAP

up/down arrows provide manual selection for steering to the desired waypoint/OAP in the sequence.

With AUTO sequential steering engaged, selecting the SEQ # option provides dashed lines on the

MPCD connecting the waypoint/OAPs of the chosen sequence.

AUTO sequential steering is deactivated when any of the following occur: the AUTO option

deselected (unboxed), the last waypoint/OAP in the sequence is within the parameters mentioned

above, selection of another steering mode, the FCS is coupled to the D/L, AUTO update is selected, a

ground point is designated, magnetic heading is invalid, aircraft present position is invalid, aircraft

ground track is invalid, or steering waypoint/OAP range/bearing is invalid.

Auto sequential steering is suspended if UPDT/DSG is selected to perform an overfly designation.

The automatic transition to the next waypoint does not take place until the update is either accepted

or rejected and the sequence criteria is satisfied.

24.2.15.5 Coupled Auto Sequential Steering. When auto sequential steering is coupled CPL SEQ

#( ) (current sequence number: 1, 2, 3, or L replaces the parenthesis) is displayed on the HUD and HSI

display and a CPLD advisory appears on the DDI. The aircraft steers to intercept the desired course

of the current WYPT/OAP in the sequence. Bank angle is limited by NAV or TAC mode as described

in chapter 2. As the aircraft gets close to the desired course, the bank angle is reduced to maintain the

aircraft on the desired course. An OVFLY( ) option is available on the WYPT data option display.

When this option is selected (boxed), the aircraft overflies the current WYPT/OAP in the sequence

before intercepting the course of the next one. When OVFLY( ) is not selected, the aircraft performs

a lead turn to intercept the course of the next WYPT/OAP just prior to reaching the current point.

Once the aircraft reaches the last point in the sequence, auto sequential steering uncouples, reverting

to HDG hold in the roll axis. RALT or BALT, whichever is selected, remains engaged when the aircraft

passes the final point. If auto sequential steering does not engage or disengages without being

commanded, an AUTOPILOT caution is displayed on the DDI, and CPL SEQ( ) flashes for 10 seconds

on the HUD and HSI displays. The caution can be cleared with the paddle switch.

Coupled AUTO sequential steering is selected and deactivated as described above in the Auto

Sequential Steering paragraph.

Coupled auto sequential steering is disengaged if UPDT/DSG is selected to perform an overfly

designation. The automatic transition to the next waypoint does not take place. When auto disengage

from coupled steering occurs, autopilot cautions occur. Coupled steering is not automatically reengaged

after the update is complete.

24.2.15.6 Groundspeed Cuing. Before groundspeed cuing is available for display, certain criteria

must be meant: a waypoint/OAP sequence must be entered, a target waypoint/OAP in the sequence

must be selected, time of day must be entered (ZTOD or LTOD), and TOT must be entered. With

waypoint/OAP great circle steering engaged to the target waypoint/OAP, the MC calculates the

groundspeed required to arrive at the target based on a direct path to the target and the entered TOT.

With AUTO sequential engaged, the MC calculates the groundspeed required to arrive at target

waypoint/OAP taking the sequential path to the target. The MC calculates the necessary groundspeed

based on the pilot entered groundspeed, providing there is enough time to travel the final leg at the

entered groundspeed and arrive at the target at the TOT. If there is not enough time to travel the final

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leg at the pilot entered groundspeed, the MC ignores the pilot entered groundspeed and calculates a

groundspeed to arrive at the target on time.

NOTE

• Programming a required groundspeed is not necessary for ground-

speed cuing calculations.

• The designated target waypoint/OAP must be in the waypoint/OAP

sequence in order for the required groundspeed cueing function to

operate.

If the target is an OAP the groundspeed required calculation includes the distance from the OAP to

the offset. If the target is NAV designated the MC uses the NAV designation location in the calculation

of groundspeed required for TOT. When the target waypoint/OAP is NAV designated, any other

designation means may be used to adjust the designation and the groundspeed calculation is calculated

to the adjusted designation.

HUD cuing of required groundspeed consists of a tick mark and arrow head located under the

airspeed box. The arrow head is referenced to the tick mark and indicates if the aircraft is traveling too

fast or too slow to reach the target on time. The arrow head is displayed to the left of the tick mark

when the aircraft is traveling too slow and to the right of the tick mark when the aircraft is traveling

too fast. Full displacement of the arrow head left or right of the tick mark indicates a difference of 30

knots between actual and required groundspeed. The aircraft is traveling the correct speed when the

arrow head is centered on the tick mark. The required groundspeed readout is displayed on the MPCD

under the present ground speed readout. See figure 24-14 for an example of HUD and MPCD

groundspeed cuing.

24.2.16 Designation. Designation of a waypoint/OAP is the action by which the pilot identifies a

waypoint/OAP position to the MC so that position can be used for sensor slaving, steering, or position

updating. Navigation and overfly designations are discussed here but sensor designations are described

in NTRP 3-22.2-EA-18G (EA-18G Classified Manual). Designating a waypoint/OAP initiates the

following changes on the MPCD: the WPDSG option is removed/replaced with the O/S option,

WYPT/OAP is replaced with a boxed TGT/OAP legend, the waypoint symbol is replaced with the

target diamond, the waypoint symbol inside the waypoint steering pointer is also replaced with the

target diamond and the steering information in the upper right corner now relates to the target.

Designating a waypoint/OAP also provides the following changes on the HUD: a target diamond

appears below the heading scale to provide target heading information, another target diamond also

appears indicating the target line of sight (LOS) and the WYPT data (range) on the lower right corner

is replaced with TGT data. HUD target steering operates the same as described for waypoint/OAP

great circle steering.

24.2.16.1

Navigation Designation (WPDSG). Selecting the WPDSG option designates the waypoint

as a target. The changes mentioned above appear at designation, see figure 24-15.

To WPDSG an OAP the procedure is slightly different. When the WPDSG option is selected, the

OAP is designated and all data for the designated target on the MPCD and HUD operate the same as

described above, except that the WPDSG legend is replaced with the O/S option and the OAP option

is boxed. The O/S option must now be selected to add the offset data to the OAP position and complete

the designation. Another method of adding the offset data to the OAP position (completing the

designation) is to assign the TDC to the MPCD and actuate the TDC. When this occurs, the O/S legend

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is removed, the boxed OAP legend is replaced with a boxed TGT legend, the offset symbol is replaced

with the target diamond and the designated aimpoint reverts to the aimpoint symbol. A WPDSG

cannot be performed if a waypoint/OAP is already designated.

24.2.16.2 Overfly Designation. An overfly designation is performed on a waypoint/OAP by pressing

the TDC while it is assigned to the MPCD and the aircraft is overflying the waypoint/OAP. When this

happens, the MC assumes that the aircraft is over the waypoint/OAP and the aircraft position at that

time is designated as the waypoint/OAP position. In the case of an OAP the offset data is automatically

added to the aircraft present position to complete the designation. When an overfly designation is

performed the changes mentioned above occur, see figure

24-16.

24.2.17 INS Updates (not available in AINS).

Radar -

Master mode - NAV (RADAR SURF) or A/G

Radar mode - EXP 1, EXP 2, EXP 3, or MAP

WYPT - SELECT

WYPT DSG - PRESS

TDC/DC - ASSIGN TO RADAR

UPDT - PRESS

DSG - PRESS

Slew cursor over waypoint and release TDC/DC.

Accept or reject.

HUD -

WYPT - SELECT

WYPT DSG - SELECT

TDC - ASSIGN TO HUD

UPDT - PRESS

DSG - PRESS

Slew HUD diamond over waypoint and release TDC/DC.

Accept or reject.

Overfly -

1. WYPT - SELECT

2. TDC/DC - ASSIGN TO MPCD

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24.3 TACTICAL AIR NAVIGATION (TACAN)

The Multifunctional Information Distribution System (MIDS) gives precise relative bearing and/or

slant range distance to a TACAN ground station or range to a suitably equipped aircraft. The TACAN

system operates in the L-band frequency range, limiting the operating range to line of sight, which

depends upon aircraft altitude. The maximum operating range is 390 nm when the selected TACAN

station is a surface beacon and 200 nm when the selected TACAN station is an airborne beacon. The

aircraft receives a three letter Morse code signal to identify the beacon being received. When operating

in conjunction with aircraft having air-to-air capability, the A/A mode provides line of sight distance

between two aircraft operating TACAN sets 63 channels apart. Up to five aircraft can determine line

of sight distance from a sixth, lead aircraft in the A/A mode.

TACAN functionality is embedded in the MIDS terminal. To preclude MIDS interference with the

IFF system, notch frequency filters were placed in the MIDS TACAN antenna lines. The upper filter

is fixed, while the lower filter is switched in for Link-16

transmissions, and out for TACAN

transmissions and all reception. Because the upper antenna filter is fixed, it filters A/A TACAN

frequencies on channels 1−36 and 64−99 (X AND Y). A/A TACAN channels should be chosen outside

of these ranges. The upper filter makes the top antenna unusable for T/R (AIR TO GROUND)

TACAN channels 1−29 X and Y, 47X to 63X and 64Y to 92Y. For TACAN channels in these ranges,

the bottom antenna is the only antenna for TACAN. With a centerline tank installed, the antenna is

blocked approximately 180 ± 15° relative to the aircraft nose. This shadowing of the bottom antenna,

combined with the lower transmitter power of the MIDS, causes reduced ranges for DME at channels

within the range of the filter when flying directly away from the TACAN station. Flight test data at

afloat stations shows that maximum tail-aspect DME ranges of approximately 22 nm at 6,000 feet and

26 nm at 15,000 feet can be expected making DME unreliable when headed outbound in the marshal

stack. At shore stations, flight tests have shown substantially better tail-aspect DME ranges (e.g. 52 nm

at 15,000 feet). DME ranges in the forward and side quadrants of the aircraft, and bearing performance

in all quadrants, are not impacted. Therefore, approach performance on the affected channels is

nominal.

NOTE

Aircraft may experience TACAN bearing and DME dropouts. Aircraft

with a centerline tank may experience loss of DME during outbound

legs from TACAN stations 1 to 29X and Y, 47X to 63X and 64Y to

92Y.

There is also attenuation on A/G TACAN channels 1 to 36 (X and Y), 40X to 63X, and 64Y to 99Y

on the upper antenna, but is less of a problem due to A/G TACAN using primarily lower antenna.

24.3.1 TACAN BIT. A TACAN BIT check is manually initiated by ensuring the TACAN is turned on

and pressing the TCN/IFF option on the BIT sublevel display. If the TACAN is good, the DDI shows

the BIT status as GO. If the TACAN does not pass the BIT check, BIT status is DEGD. The TACAN

system also has an automatically initiated BIT. If the automatic BIT check detects a wrong signal or

a failure, TACAN DEGD is displayed on the BIT display and the BIT line on the left DDI. If no fault

is detected, nothing is displayed next to TCN.

24.3.2 TACAN Mode Selection. To enable the TACAN system, select the TCN option on the UFCD

top level CNI display. The TACAN channel number is displayed on the TCN option. If the TACAN

is powered the TCN option is corner highlighted. If TCN is selected with no data entered in the

scratchpad the TACAN sublevel is displayed, see figure 24-17. TACAN operation is controlled from

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Figure 24-17. TACAN Mode Selection

the TACAN sublevel. The TACAN system is turned on by pressing the ON/OFF option on the TACAN

sublevel.

When the TACAN sublevel is selected, the following TACAN mode options appear: T/R (transmit/

receive), RCV (receive), A/A (air-to-air), and X and Y channel. Border highlights indicate which TACAN

mode is operating. In the T/R mode the TACAN computes bearing and measures slant range from the

selected TACAN station. In the RCV mode only bearing from the selected TACAN station is computed. In

the A/A mode, interrogations and replies are single pulse from one aircraft to another. The TACAN channel

mode is indicated in the X/Y option which is always border highlighted in the TACAN sublevel and toggles

between X and Y mode with each selection.

24.3.3 TACAN Programming. TACAN station data is entered by selecting the DATA option on the

HSI top level display. Selecting the TCN option on the data sublevel display provides the TACAN data

sublevel display. This display shows the TACAN station lat/long position, elevation, and magnetic

variation. TACAN station data is entered by selecting the desired TACAN station number on the

UFCD keyboard. Pressing the X or Y option to select the TACAN channel, the POSN option enters

lat/long data, the ELEV option to enter elevation data, and the MVAR option to enter magnetic

variation. TACAN data is entered on the UFCD keypad for up to 252 TACAN stations (126 on X

channel, 126 on Y channel). See figure 24-18.

24.3.4 TACAN Position Keeping. The TACAN system may be used for position keeping purposes. To

do this the TACAN system must be in the T/R mode with the proper channel (X or Y) and channel

number selected. The TACAN station selected must be one of the prestored stations. Selecting the

POS/XXX option on the HSI top level display provides the position keeping option display. Selecting

the TCN option as the position keeping source causes the HSI top level display to be returned and

POS/TCN to be displayed as the position keeping source.

24.3.5 TACAN Position Updating. The TACAN system may also be used for position updating

purposes. To do this the TACAN system must be in the T/R mode with the proper channel (X or Y)

and channel number selected. The TACAN station selected must be one of the prestored stations.

Selecting the UPDT option on the HSI top level display provides the UPDT option display. Selecting

the TCN option causes the MC to use position data from the selected TACAN station to compute

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aircraft present position. The difference between the TACAN computed present position and the on

board determination of aircraft present position produces the position error readout in bearing and

range on the ACPT/REJ display. Selecting the ACPT option accepts the position update and returns

the HSI top level display. Selecting the REJ option rejects the update and returns the HSI top level

display.

24.3.5.1 TACAN Steering. Types of TACAN steering available for selection are direct great circle,

and course line steering. These TACAN steering options are mechanized identical to waypoint/OAP

direct great circle and course line steering, with steering being referenced to the TACAN. Selecting the

TCN option on the HSI top level display provides TACAN direct great circle steering, see figure 24-19.

Activating the CSEL switch with TACAN direct great circle steering selected provides TACAN course

line steering, see figure 24-20.

24.3.5.2 Coupled TACAN Steering. When TACAN steering is coupled, CPL TCN is displayed on the

HUD and HSI display and a CPLD advisory appears on the DDI. The aircraft steers to intercept the

desired course line, or flies to the TACAN station if no course line is selected. Bank angle is limited by

NAV or TAC mode as described in chapter 2. As the aircraft gets close to the desired course, the bank

angle is reduced to maintain the aircraft on the desired course. If a course line is selected, the aircraft

continues past the TACAN station on the outbound radial until the mode is decoupled. If no course

line is selected, TACAN steering uncouples when the aircraft reaches the TACAN station, reverting to

HDG hold. RALT or BALT, whichever is selected, remains engaged when the aircraft passes the

TACAN station. If TACAN steering does not engage or disengages without being commanded, an

AUTOPILOT caution is displayed on the DDI, and CPL TCN flashes for 10 seconds on the HUD and

HSI displays. The caution can be cleared with the paddle switch.

24.4 ICLS - INSTRUMENT CARRIER LANDING SYSTEM

The AN/ARA-63A ICLS is an all weather approach guidance system which operates with an aircraft

carrier installed transmitting set AN/SPN-41. The ICLS decodes transmitted azimuth and elevation

signals during an approach and provides steering information for display on the HUD, standby attitude

reference indicator, and EADI. The major components of the AN/ARA-63A system are a receiver and

a decoder.

24.4.1 ICLS Receiver. The ICLS receiver receives coded transmissions of azimuth and elevation

guidance data from surface transmitters. The receiver transforms these signals into coded pulses

suitable for processing in the decoder. A BIT module for system BIT check is contained within the

receiver.

24.4.2 ICLS Decoder. The ICLS decoder receives and decodes azimuth and elevation pulses from the

receiver and converts them to azimuth and elevation command signals for the HUD and standby

attitude reference indicator.

24.4.3 ICLS BIT. An ICLS BIT check is manually initiated by ensuring the ICLS is on and selecting

the ILS/AUG/BCN/D/L option on the BIT sublevel display. If any of the BIT monitored outputs fail,

a BIT status message of DEGD (degraded) appears on the BIT sublevel display. If the BIT checks are

good, a BIT status message of GO appears on the BIT sublevel display.

24.4.4 ICLS Initialization. The ICLS is enabled by placing the ILS UFC/MAN switch on the COMM

control panel to the UFC position, pressing the D/L BCN ILS option, and pressing the ILS option, on

the UFCD. This allows the ICLS channel number and ON/OFF status to be displayed on the UFCD

and CHNL # to appear on the CHNL option, see figure 24-21. Pressing the ON/OFF option turns the

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Figure 24-21. ICLS Initialization

ICLS on. The ICLS channel may be changed (1 to 20) using the UFCD keypad. The ICLS is

automatically selected when the ACL data link mode is selected.

Another method of enabling the ICLS is to place the ILS UFCD/MAN switch on the COMM control

panel to the MAN position. When this is done the ICLS is turned on and the ILS channel push buttons

on the COMM control panel are used for channel selection. The letters MAN appear on the scratchpad

and below the CHNL option.

24.4.5 ICLS Steering. When the ICLS is on and the ILS option on the HSI top level display is

selected (boxed), ICLS steering is provided on the HUD, the standby attitude reference indicator, and

the EADI, see figure 24-22. The azimuth and elevation deviation bars are referenced to the velocity

vector. When the waterline symbol is displayed, the deviation bars are referenced to it. As shown, the

deviation bars are deflected full scale and the aircraft is below glide slope and to the left of course. The

azimuth bar is deflected full scale for azimuth deviations of ±6° to ±20°. The elevation bar is deflected

full-scale down for elevation deviations of 1.4° to 20°, and full-scale up for deviations of -1.4° to -3°.

If a valid azimuth or elevation signal is not received by the ICLS, the corresponding bar is not

displayed.

ICLS steering is automatically provided when the ACL mode is selected and valid ICLS steering

signals are received.

24.5 DATA LINK SYSTEM

All information on the data link system, except for the automatic carrier landing mode, is contained

in NTRP 3-22.2-EA-18G (EA-18G Classified Manual). For typical Automatic Carrier Landing

procedures, refer to Chapter 8.

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24.5.1 Automatic Carrier Landing (ACL) Mode. The system for automatic landing of aircraft onto

the aircraft carrier deck is comprised of the AN/SPN-42 or AN/SPN-46 installed aboard the carrier

and Automatic Carrier Landing (ACL) equipment installed in the aircraft. The aircraft data link

system is the ACL component over which steering commands are received from the carrier for guidance

of the aircraft.

The data link automatic carrier landing (ACL) mode is available only when the NAV master mode

is selected. The ACL steering commands may be coupled to the flight control computer for fully

automatic approaches to touchdown, or the pilot may elect to use the steering displays for a manually

controlled landing. The traffic control (T/C) mode is a submode of ACL. The T/C mode provides data

link heading commands to aid the pilot in reaching the marshal point and/or it may be used for

azimuth alignment from marshal until ACL acquisition. These heading commands can be coupled to

the flight control computer for automatic lateral axis control or can be used for manual steering aids.

Two uplinked control messages (label 5 and label 6) are uniquely addressed to a specific aircraft and

received by the data link for ACL mode (and T/C submode) control and display. The label 5 message

is used only for T/C mode, while both label 5 and label 6 are required for ACL modes 1, 1A, and

control and display. The contents of the uplinked label 5 and label 6 messages follows:

Label

Message

Command Altitude

Displayed on SA display.

(feet)

Command Airspeed

Displayed on SA display.

(knots)

Command Rate of

Displayed on SA display.

Descent

(feet per minute)

Command Heading

Displayed on SA and HUD.

Group 1 Discretes

ACL RDY, CMD CNT, LND CHK, NOT

CMD, W/O, and CHG CHNL.

Group 2a Discretes

Monitor Altitude and Altitude Change

Warning

Receipt of either discrete causes the Command

Altitude and Command Rate of Descent to be

underlined on the SA display.

Group 2b Discretes

Monitor Speed and Speed Change Warning.

Receipt of either discrete causes the Command

Airspeed to be underlined on the SA display.

Group 2c Discretes

ADJ A/C, VOICE and 10 SEC.

Label

Message

Vertical Glide Slope Error

Used for data link HUD situation display.

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Label 6 Message

Lateral Glide Slope Error

Used for data link HUD situation display.

Mode Status Discrete

Indicates that uplinked longitudinal and lateral

axes commands may be used for mode 1 ap-

proach.

Longitudinal Axis Command

Used by FCS for longitudinal axis control.

(altitude rate in feet/second)

Lateral Axis Command

Used by FCS for lateral axis control.

(roll angle in degrees)

The ground station also periodically uplinks two universal test messages (UTM-3A and UTM-3B).

These two messages have a canned constant content and carry a universal address, rather than being

addressed uniquely to a controlled aircraft, as are the label 5 and label 6 messages. During ACL mode

test, the data link is commanded to accept these two UTM as part of the determination of onboard

ACL capability.

24.5.1.1 ACL Mode Displays. The ACL mode displays consist of the SA display on the DDI and the

data link situation display on the HUD. The following paragraphs contain a general description of the

Figure 24-23. DDI SA ACL Display

displays related to the ACL mode. A more explicit definition of the utilization of these displays is

presented in ACL Mode Operation, this chapter.

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24.5.1.1.1 SA Display. Figure 24-23 shows the ACL and T/C information which may be displayed on

the link SA display. The lettered symbols and cues on the display are described after the corresponding

letter in the following paragraphs.

a. The following uplinked group 1 discretes may be displayed in this slot:

LND CHK Landing check indicates that SPN-42/SPN-46 control radar communication has

been established. It also cues the pilot to be in the landing configuration with ATC

engaged.

ACL RDY ACL ready indicates that SPN-42/SPN-46 acquisition has occurred and uplinked

longitudinal axis (altitude rate) and lateral axis (roll rate) commands are being

received equal to zero. The ACL RDY indication is also displayed on the HUD.

Receipt of the ACL RDY discrete is one of the onboard prerequisites for ACL

couple.

CMD CNT Command control discrete indicates that the carrier has received a verbal confir-

mation from the pilot that FCS is coupled to the ACL longitudinal and lateral

commands, and further indicates to the pilot that longitudinal and lateral com-

mands are now active.

W/O

When this discrete is received the FCS is uncoupled from the uplinked commands.

NOT CMD The not command discrete indicates that label 5 information is invalid. When this

discrete is received the label 5 information is removed from the SA display and the

FCS is uncoupled from the T/C heading command/ACL steering commands.

CHG

The change channel discrete indicates that the data link frequency should be

CHNL

changed.

b. The following ACL mode operational cues may be displayed in this slot.

MODE 1

Indicates that the entire loop is capable and ready for coupling for dual axes ACL

control.

MODE 2

Indicates that the entire loop is not capable of Mode 1 coupled approach but is

capable of Mode 2 manual control approach using uplinked situation steering.

T/C

Traffic control cue indicates that the entire loop is capable and ready for couple to

the T/C heading command.

TILT

Indicates that the uplinked information is not being updated. When this condition

exists all uplinked information is removed from the displays and the FCS is

uncoupled from the data link commands.

c. The following uplinked group 2 C discretes may be displayed in this slot. These cues are

displayed for 30 seconds after initial receipt, then removed.

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10 SEC

Indicates that SPN-42/SPN-46 is now adding deck motion compensation to the

longitudinal and lateral axes commands. This discrete is received approximately

12.5 seconds before touchdown.

ADJ A/C

Adjacent aircraft cue indicates that another aircraft has been detected in the area

of controlled aircraft.

VOICE

Indicates that the pilot is to establish voice contact with control.

d. The following onboard capability cues are displayed in this slot.

ACL 1

Indicates that onboard systems are capable of an ACL or T/C couple to the FCS.

ACL 2

Indicates that onboard systems are not capable of ACL or T/C couple to FCS, but

are capable of displaying uplinked information for a mode 2 manual approach.

ACL N/A Indicates that onboard systems are not capable of using uplinked information and

that a carrier controlled approach (CCA) must be made.

TEST

Indicates that ACL mode is in test.

e. The UTM FAIL cue is displayed in this slot when valid uplinked UTM 3A and UTM 3B were

not received during automatic test.

f. Command heading is displayed by the double chevron symbol on the outside of the compass

rose.

g. Command airspeed is displayed in this slot.

h. Command altitude is displayed on this slot.

i. Command rate of descent is displayed in this slot.

j. The compass rose is track-up oriented with selectable ranges of 10, 20, 40, 80, 160, and 320 nm.

24.5.1.1.2 HUD ACL Display. Figure 24-24 shows the HUD ACL display information. The lettered

symbols and cues on the HUD are described after the corresponding letter in the following paragraphs.

a. Uplinked command heading is indicated by the command heading steering pointer below the

heading scale.

b. The following cues may be displayed in the command heading slot:

10 SEC

Displayed for 30 seconds after receipt and then removed. Also displayed on SA dis-

play.

TILT

Displayed when communication has been lost with data link control. Also on SA

display.

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DATA

Displayed for 10 seconds and flashed at a rate of two times per second when new

data is initially displayed on the SA display.

W/O

When this discrete is received the FCS is uncoupled from the uplinked commands.

c. The following cues may be displayed in this slot:

ACL RDY Displayed when received via data link and the FCS is not coupled. Also displayed

on SA display.

CPL P/R Coupled in pitch and roll is displayed when the FCS is coupled to the longitudinal

and lateral commands. The cue is flashed for 10 seconds at two times per second

then removed if the couple attempt is unsuccessful, or if uncouple occurs for any

reason other than pilot deselection. Disengagement, other than pilot initiated, also

results in an AUTOPILOT caution.

CPL HDG Coupled to heading commands cue is displayed when FCS is coupled in the T/C

mode. This cue is flashed for the same reasons as described for the CPL P/R cue.

d. The following cues may be displayed in this slot. These cues may be displayed in any master

mode:

ATC

Displayed when automatic throttle control is engaged. If an unsuccessful engage-

ment attempt occurs, or if the ATC disengages for any reason other than pilot

deselection, the ATC cue is flashed for 10 seconds at two times per second, then

removed.

NWS

Indicates low gain nosewheel steering is engaged.

NWS HI Indicates high gain nosewheel steering is engaged.

e. When ACL mode is initially selected, waypoint steering is automatically deselected, if selected,

and the system is automatically undesignated if an aimpoint is designated. If TACAN is on,

TACAN range is automatically displayed regardless of TACAN steering selection unless the

pilot subsequently designates an aimpoint or selects waypoint steering.

f. The tadpole steering symbol is referenced to the velocity vector and provides uplinked flight

path steering indications for the ACL glide slope and course.

24.5.1.2 ACL Mode Operation. The data link ACL mode is selected by actuating the ACL option

button on the MPCD.

24.5.1.2.1 Initialization. When selected, the ACL legend on the MPCD is boxed and the SA display

is automatically selected on the left DDI. The TEST cue is displayed indicating the ACL mode is in

test. The ICLS, data link, and radar beacon are automatically turned on if not previously on. IBIT is

run on the data link and radar beacon systems. The uplinked UTM is monitored for valid receipt.

When ACL testing is complete the TEST cue is removed, the systems are placed in the correct

operational mode, the stored data link ACL frequency is automatically selected, and the pilot is cued

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Figure 24-24. HUD ACL Display

on the SA display to onboard ACL capability (ACL 1, ACL 2, or ACL N/A) as previously described. If

during test, a valid uplinked UTM message was not received, the UTM FAIL cue is displayed on the

SA display.

24.5.1.2.2 Traffic Control Couple. When an uplinked label 5 message is received, a determination is

automatically made relative to total loop capability. If the ACL loop is ready for a T/C couple, the T/C

cue appears on the SA display and autopilot options are initialized on the upfront control display with

the CPL HDG option displayed (figure 24-25). The prerequisites for a CPL HDG option for T/C

follows:

1. Onboard systems fully operational.

2. Valid label 5 message received.

3. Waveoff (W/O) discrete not received.

4. Uplinked information being updated (no TILT cue).

5. NOT CMD discrete not being received.

6. Label 6 message not being received.

With T/C displayed FCS couple is selected by actuating the CPL option button on the UFCD. When

coupling to the T/C heading command is successful a colon is displayed in front of the CPL option on

the UFCD and the CPL HDG cue is displayed on the HUD. After couple the FCS banks the aircraft

to a maximum of 30° to capture and hold the uplinked heading command. Aircraft pitch attitude may

be controlled by the pitch hold function of the heading hold mode or by the BALT or RALT altitude

hold modes of the autopilot. A T/C couple precludes use of all other outer loop autopilot modes except

BALT and RALT. The T/C couple disengages, with reversions as noted, for any of the following

reasons:

1. Heading hold mode disengagement with reversion to CAS operation.

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When the pilot selects the CPL P/R option on the UFCD, an ACL couple to the FCS is requested

if prerequisites are met.

NOTE

If FCS is already coupled to T/C command heading, actuation of the

CPL HDG option disengages T/C couple and a second actuation (CPL

P/R) requests ACL couple.

The MC prerequisites for initial ACL couple are:

1. Basic FCS outer loop (heading hold) engaged. If heading hold is not engaged when the CPL

option is actuated it is automatically requested, and when FCS indicates it is engaged, ACL couple

is requested.

2. Onboard test results indicate ACL 1 capability.

3. Uplinked ACL RDY discrete being received. ACL RDY is required for initial couple only. It is not

required after ACL couple occurs.

4. Uplinked A/P bit set to couple state.

5. Valid uplinked longitudinal and lateral axes commands being received (no TILT).

The CPL P/R option is highlighted on the UFCD and the CPL P/R cue is displayed on the HUD to

indicate FCS is coupled. When ACL couple initially occurs, the FCS fades in the longitudinal and

lateral uplinked commands to minimize engagement transients. After FCS is coupled to the dual-axis

commands, the FCS limits the accepted magnitude of the uplinked commands to prevent excessive

pitch or roll changes due to large and/or erroneous uplinked commands. When FCS is coupled to ACL,

uncouple occurs, with reversion as noted, for any of the following reasons.

1. Heading hold mode disengagement with reversion to CAS operation.

2. Pitch or roll control stick steering engagement with reversion to CAS when CSS is no longer

engaged.

3. WonW with reversion to CAS.

4. Paddle switch actuation with reversion to CAS.

5. UFCD CPL option actuation with reversion to CAS.

6. Receipt of W/O discrete with reversion to CAS.

7. Receipt of command degrading approach to mode 2 state with reversion to CAS.

8. Loss of valid uplinked commands for more than 2 seconds (TILT) with reversion to CAS.

9. Detection of degraded onboard capability below that required for MODE 1 with reversion to CAS.

10. Selection of FLAPS AUTO.

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11. MC Failure or selected to OFF

NOTE

With MC1 failed or selected to OFF and coupled ACLS previously

engaged, the option to re-couple to ACLS is not presented on the

autopilot page of the UFCD when MC1 is restored. Deselecting and

then reselecting ACL on the HSI will bring the CPL P/R option back

if all coupled ACL engagement conditions are satisfied after the ACL

TEST sequence is complete. If MC2 is cycled with ACL selected, the

CPL P/R option is available without having to deselect/reselect ACL.

During an ACL coupled approach the D/L situation steering and the ICLS situation steering may

remain selected for HUD display to allow the pilot to monitor the progress of the automatic control in

capturing and holding the desired glide slope and azimuth.

NOTE

The D/L situation steering may be removed from the HUD by

unboxing ACL on the MPCD, however, reselection of the ACL option

reinitializes the system as described in section 24.6.1.2.1.

24.5.1.2.4 ACL Mode 1A. For an ACL mode 1A approach, the aircraft may be coupled to data link

commands as described in the Mode 1 paragraph, then uncoupled at minimums (200 feet and 0.5 mile)

and manual control as described for Mode 2 used the rest of the way to touchdown.

24.5.1.2.5 ACL Mode 2. When a label 6 message is initially received and a mode 1 or mode 2

capability exists, a mode 2 manual approach may be made. Data link HUD steering is automatically

selected. The data link situation steering tadpole is displayed on the HUD with the tadpole referenced

to the velocity vector as shown in figure 24-27. The ICLS situation display may remain selected on the

HUD for cross check on the D/L situation display and/or either D/L or ICLS display may be deselected

by actuating the option button on the MPCD. Mode 2 approaches may be made with or without ATC

engaged, but ATC should be used for angle of attack/airspeed control, if it is available. If ATC is not

engaged the HUD angle of attack bracket should be used to control AOA/airspeed and the glide slope

maintained by flying the D/L situation steering display on the HUD.

24.5.1.3 Typical ACL Approach. Figures 24-26 and 24-27 describe the controls and displays for a

“canned” mode 1 ACL approach. The ACL mode is optimized for the described approach, but

abbreviated approaches and/or deviations as required may be used, dependent upon existing

operational procedures and collaboration between the pilot and carrier control. Figure 24-27 shows a

plan view of the approach with controls and displays for selected points prior to marshal. Figure 24-28

shows descent from marshal to touchdown. The depicted scenario uses only D/L steering and

commands complemented with ICLS steering in order to more clearly define D/L capability. It does

not show TCN or WYPT steering which may be used in conjunction with, or independent of, D/L

steering during the approach.

24.6 NAVIGATION DATA ENTRY

The UFCD has two data entry protocols, Standard Data Entry (SDE) and Fast Data Entry (FDE).

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CHAPTER 25

Backup/Degraded Operations

25.1 MISSION COMPUTER FAILURE

25.1.1 Mission Computer Failure

25.1.1.1 Mission Computer Failure - Single. In the event of a MC failure, backup functions are the

same in either computer. Basic navigation and situational awareness functions are available, and

cautions and advisories are displayed. TACAN and IFF can be turned off/on in backup mode. TACAN

station ID or IFF mode code changes can be entered during backup mode operation. The radar

altimeter cannot be turned on/off, but the RALT bug can be entered via the UFCD. ACL Mode II is

available in MC backup mode. Autopilot, G-limiter and roll limiter are not available in MC backup

mode.

25.1.1.2

Mission Computer Failure - Dual. When both MCs are offline or in initialization, the SDC

acts as the backup bus controller and transmits a limited HUD display of essential flight information

to the forward MPCD and forward UFCD. The FCC provides calibrated airspeed, AOA, Mach, vertical

velocity, and baro altitude. The CSC provides pitch and bank attitude reference and radar altitude. See

figure 25-1. The SDC also provides L ATS and R ATS cautions.

25.1.1.3 Backup Navigational Information on Backup HUD. The navigational information on the

backup HUD is identical to the full-up HUD. Limited A/A and no A/G support is available.

25.2 BACKUP ATTITUDE AND NAVIGATION SYSTEM

If a failure occurs in the primary attitude and navigation system (INS), output signals of pitch, roll,

magnetic heading, and airspeed are provided to the mission computer system for use in the backup

attitude navigation computations. The backup system consists of standby attitude reference indicator,

static power inverter, and magnetic azimuth detector.

25.2.1 Standby Attitude Reference Indicator. The standby attitude reference indicator (figure 25-2)

is a self-contained pitch and roll instrument which is mounted on the main instrument panel. An

electrically driven gyro maintains vertical orientation by use of an electronic erection system. The

erection system automatically cuts off when lateral accelerations exceed approximately 0.15 g. The

gyro spin speed and erection system provides a minimum of 3 minutes of attitude information with a

total power loss. Pitch and roll servos provide back up pitch and roll attitude for use by other systems.

The attitude presentation is 360° in roll, 92° in climb, and 78° in dive.

25.2.2 Static Power Inverter. If there is an interruption or loss of aircraft ac power, 28 volt dc power

is applied to the static power inverter to produce the 115 volt ac power needed for standby attitude

reference indicator operation.

NOTE

The aft cockpit standby attitude reference indicator is not powered by

the essential bus. Hence, it only operates for 3 minutes after a loss of

aircraft ac power.

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Figure 25-1. SDC Backup HUD Display

25.2.3 Magnetic Azimuth Detector. The magnetic azimuth detector (MAD) consists of three sensing

elements configured in a wye. The sensing elements are mounted so that average positions are

maintained in the horizontal component of the earth magnetic field. The air data functions process the

detected magnetic heading and develop the magnetic error compensation signals.

25.2.4 Backup Attitude and Navigation System Controls and Indicators. The controls and indica-

tors for the backup system are on the AMPCD and the standby attitude reference indicator.

25.2.4.1

AMPCD. The AMPCD provides horizontal situation and steering control displays.

25.2.4.2 Standby Attitude Reference Indicator Controls and Indicators. The controls and indica-

tors on the standby attitude reference indicator (figure 25-2) are described as follows:

1. OFF flag. This flag is in view when power is removed or the pull to cage knob is pulled out.

2. Miniature aircraft. This represents the nose and wings of the aircraft and indicates pitch and roll

attitude relative to the horizon. The miniature aircraft is adjustable through ±5° of pitch trim by

rotating the pull to cage knob clockwise or counterclockwise when the knob is pushed in.

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3. Pull to cage knob. The knob is pulled out and held to orient the gyro spin axis to the ARI case

(pitch position). When the knob is pulled out and rotated clockwise to engage detent, the ARI

becomes caged.

Do not lock the gyro in the caged position with the pull to cage knob if

the gyro is spinning. Damage to the gyro might occur if the indicator or

the aircraft is moved while the gyro is spinning and caged. If the knob is

in the locked position, it must be pulled out to clear the detent before it

can be turned counterclockwise.

4. Slip indicator (inclinometer). This mechanical indicator displays sideslip.

5. Rate of turn needle. This needle displays the rate of turn. One needle width of deflection indicates

a 90° per minute rate of turn.

6. Test switch. The vertical and horizontal pointers and rate of turn needle are deflected when the

test switch is pressed.

7. Pointer shield. This shield conceals the vertical pointer in the stowed position.

8. Elevation deviation bar. This bar provides direction information for pitch steering.

9. Bank scale. The scale rotates with the aircraft to provide measurement of angular displacement

by the bank angle index during maneuvers.

10. Azimuth deviation bar. This bar provides direction information for azimuth steering.

11. Sky pointer. The pointer rotates with the aircraft to indicate vertical (sky) in any roll attitude.

12. Bank angle index. The index indicates vertical in any roll attitude.

13. Display sphere. The sphere is directly coupled to the gyro gimbals to provide a direct reading of

pitch and roll. The sphere is marked at each 5° in pitch.

25.3 NAVIGATION BACKUP

Position keeping for aircraft navigation requires available sources of heading information, attitude

information, and velocity. The INS normally provides position keeping for the aircraft. Under various

failure conditions alternate sources of heading, attitude, and/or velocity information may be used for

position keeping. The backup heading modes are discussed in a following paragraph. The attitude

reference indicator is the alternate source of attitude information. The alternate sources of velocity

information are air data (true airspeed and angle of attack) or radar doppler velocities. Air data vertical

velocity is an alternate velocity source if only the vertical component of INS velocity is invalid. The

flight control set is an alternate source for angle of attack information.

The system automatically reverts to alternate data sources under failure conditions. For example, air

data position keeping is automatically selected in case of an INS failure. If MIDS is installed and

operating, MIDS is automatically selected as the aircraft position keeping source when INS or GPS

fails. Because MIDS position keeping is unreliable, POS/ADC should be manually selected if

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Figure 25-2. Standby Attitude Reference Indicator

POS/MIDS is displayed. Air data position keeping uses true airspeed, and angle of attack from the air

data functions, and the last computed wind or the wind inserted by the pilot on the UFCD. The wind

can also be updated during air data position keeping by performing a velocity update. A new wind is

calculated when the velocity update is accepted. The velocity vector on the HUD is flashed at a slow

rate (on for 0.8 seconds and off for 0.8 seconds) during air data position keeping. A POS/ADC caution

is displayed on the DDI along with a master caution light and tone when the INS reverts to ADC

position keeping.

The radar doppler velocities are automatically used by the mission computer if available and no

other velocity sources are available (INS, GPS and FCC air data failed). This applies whether or not

TACAN position keeping is selected. Doppler velocities are available when the radar is operating in a

doppler beam sharpened (DBS) mode or PVU mode. The MC automatically uses the doppler velocities

under these conditions if a DBS mode is selected or if velocity update is selected without accepting or

rejecting the update.

25.3.1 Navigation Controls and Indicators.

25.3.1.1 HSI Display. The symbols and digital readouts that normally appear on the HSI during

backup system operation are the same as in the INS operation except for the POS option display.

25.3.1.2 POS Option Display. Pressing the POS/ADC pushbutton on the HSI display commands the

mission computer to use air data function true air speed, MAD heading, and wind speed and direction

to compute aircraft latitude and longitude in waypoint steering computations.

25.3.2 Backup Heading Mode Control. If the INS computer fails or if the INS switch is rotated to

the GYRO position the INS reverts to the gyro mode and true heading is no longer available from the

INS. The mission computer slaves the INS platform heading with the MAD to provide damped

magnetic heading. The slaving of the INS platform to the MAD occurs in straight and level flight.

During maneuvers, when roll is greater than ±5° or pitch is greater than ±10°, the MAD output is not

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used. Upon reversion to the Slaved heading mode, the bottom row of option selections on the HSI are

HDG/SLV, SYNC, and ERECT. The SYNC option can be used to quickly synchronize the heading

with the MAD output if a heading error exists. The MC automatically synchronizes the heading with

the MAD output when the heading error is greater than 11.25° during level flight. Pressing the ERECT

option commands the INS to increase the gains in the INS erection loops, fast-leveling the platform.

SYNC and ERECT are momentary options and should be used only in straight and level flight.

If it is desired to change the backup heading mode, the heading status option pushbutton should be

pressed (HDG/SLV in this case) and the available heading options (SLV, DG, and COMP) are

presented on the HSI. Selecting any of these options commands the MC to display the selected option

and the necessary controls for that option. For failure conditions the next best available source is

automatically selected.

Selection of the DG heading mode or failure of the MAD while in the HDG/SLV mode causes the

bottom pushbuttons on the HSI to display HDG/DG, HDG (arrow left), HDG (arrow right), and

ERECT. The MC computes aircraft heading using the INS platform heading as a smoothed heading

source to compensate for the difference between true north, platform heading (wander angle), and

earth rate. The aircrew may correct the aircraft heading by using the HDG slew option buttons.

Following the initial setting of heading, the MC provides heading compensation for earth rate but

changes in magnetic variation must be entered using the UFCD because the aircraft uses the last

known value of magnetic variation.

If the aircrew selects the compass heading mode, if the INS is turned off, or if the INS fails

completely the mission computer uses the MAD output, damped with body rate data from the flight

control system. During maneuvers, when roll is greater than ±5° or pitch is greater than ±10°, the flight

control system body rates are used to determine heading. In the compass heading (HDG/COMP) mode,

the bottom buttons are labeled HDG/COMP and ERECT. The ERECT option is displayed when the

INS is operating in the AHRS mode. The MC uses the last known magnetic variation to compute true

heading.

25.4 BACKUP FREQUENCY CONTROL

Backup frequency control for the radios in case of an UFCD or MPCD malfunction is provided by

the multiplex bus and a DDI display. The UFC backup (UFC BU) display can be selected from the

SUPT menu. Both comm 1 and comm 2 can be controlled from the UFC BU display. When the COM1

or COM2 button is pressed, the frequency on which that radio is operating is displayed below the

legend COM1 or COM2, as appropriate. A new frequency is selected by selecting OVRD and using the

numerical buttons along the sides of the display and the ENT button at the bottom. Frequencies can

be entered to 5 KHz of resolution. As the new frequency is entered, it is displayed in the scratchpad

above the COM1 or COM2 legend. When the ENT button is pressed, the frequency displayed in the

scratchpad is stored in the mission computer as the preset frequency for the radio. Pressing the CLR

button clears the scratch pad if an error is made when entering a backup frequency. Selecting the

OVRD option in the upper right corner of the display boxes the option and the radio operates on the

preset frequency stored in the mission computer, overriding the normal frequency control from the

UFCD. Frequency control reverts to the UFCD when OVRD is deselected. The frequency displayed

below the COM1 or COM2 legend is always the frequency on which the radio is operating, whether or

not OVRD is selected. Upon power up with WonW, the preset frequencies stored in the mission

computer for COM1 and COM2 are initialized to be the same as the last valid radio operating

frequencies.

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CHAPTER 26

Visual Communications

Communications between aircraft are visual whenever possible. Flight leaders shall ensure that all

pilots in the formation receive and acknowledge signals when given. The visual communications

chapters of NAVAIR 00-80T-113 should be reviewed and practiced by all pilots. Common visual signals

applicable to flight operations are listed in figure 26-1.

GENERAL SIGNALS

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

Thumbs up, or nod of

Flashlight moved verti-

Affirmative. (‘‘Yes’’, or,

head.

cally up-and-down re-

‘‘I understand.’’)

peatedly.

Thumbs down, or turn

Flashlight moved hori-

Negative. (‘‘No’’, or, ‘‘I

of head from side to

zontally back-and-forth

do not understand.’’)

side.

repeatedly.

Hand cupped behind ear

Question. Used in con-

As appropriate.

as if listening.

junction with another

signal, this gesture indi-

cates that the signal is

interrogatory.

Hand held up, with

Wait

palm outward.

Hand waved back and

Letter N in code, given

Ignore my last signal.

forth in an erasing mo-

by external lights.

tion in front of face,

with palm turned for-

ward.

Employ fingers held ver-

Numerals as indicated.

A nod of the head (‘‘I

tically to indicate de-

understand’’). To verify

sired numeral 1 through

numerals, addressee re-

5. With fingers horizon-

peats. If originator nods,

tal, indicate number

interpretation is correct.

which added to 5 gives

If originator repeats nu-

desired number from 6

merals, addressee should

to 9. A clenched fist in-

continue to verify them

dicates 0. (Hold hand

until they are under-

near canopy when sig-

stood.

naling.)

Figure 26-1. Visual Communications (Sheet 1 of

VII-26-1

ORIGINAL

A1-E18GA-NFM-000

TAKEOFF, CHANGING LEAD, LEAVING FORMATION, BREAKUP, LANDING

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

1. Section/Division

1. I am ready to take

1. Standby for re-

Lead gives thumbs up.

Lead turns formation

position on the runway.

sponse from wingman.

lights off.

2. Wingman gives

2. Wingman turns for-

2. I am ready to take

2. Lead calls for take-

thumbs up.

mation lights off.

position on the runway.

off.

2a. Wingman turns

2a. I am ready for

2a. Section/Division

formation lights on.

takeoff roll.

Lead formation lights

on.

3. Section/Division

3. I am executing

3. Wingman roll in

Lead kisses off wingman.

Lead turns formation

takeoff roll.

order.

lights on.

1. Leader pats self on

1. Lead aircraft turns

Leader shifting lead to

1. Wingman pats head

the head, points to wing-

strobe lights ON.

wingman.

and assumes lead.

man.

2. If external lights

2. Wingman turns

are inoperative, leader

strobe lights OFF and

shines flashlight on

assumes lead.

hard-hat, then shines

light on wingman.

If external lights are

inop-

3. Wingman shines

flashlight at leader, then

on his hard hat and as-

sumes lead.

Leader pats self on head

Leader shifting lead to

Wingman relays signal;

and holds up two or

division designated by

division leader desig-

more fingers.

numerals.

nated assumes lead.

Pilot blows kiss to

I am leaving formation.

Leader nods (‘‘I under-

leader.

stand’’) or waves good-

by.

Leader blows kiss and

Aircraft pointed out

Wingman indicated

points to aircraft.

leave formation.

blows kiss and executes.

Leader points to wing-

Directs plane to investi-

Wingman indicated

man, then points to eye,

gate object or vessel.

blows kiss and executes.

then to vessel or object.

Figure 26-1. Visual Communications (Sheet 3 of 9)

VII-26-3

ORIGINAL

A1-E18GA-NFM-000

TAKEOFF, CHANGING LEAD, LEAVING FORMATION, BREAKUP, LANDING (CONT)

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

Division leader holds up

Section break off.

Wingman relays signal

and rotates two fingers

to section leader. Section

in horizontal circle, pre-

leader nods (‘‘I under-

paratory to breaking off.

stand’’) or waves

good-by and executes.

Leader describes hori-

Series of ‘‘I’s’’ in code,

Breakup (and rendez-

Wingman take lead, pass

zontal circle with fore-

given by external lights.

vous).

signal after leader breaks

finger.

and follow.

Landing motion with

Refers to landing of air-

open hand:

craft, generally used in

conjunction with another

signal.

1. Followed by patting

1. I am landing.

1. Nods. (‘‘I under-

head.

stand’’) or waves good-

by.

2. Followed by pointing

2. Directs indicated air-

2. Aircraft indicated

to another aircraft.

craft to land.

repeats signal, blows a

kiss and executes.

Open hand held verti-

Adjust wing position for-

Wingman moves in di-

cally and moved forward

ward or aft.

rection indicated.

or backward, palm in

direction of movement.

Open hand held horizon-

Adjust wing position up

Wingman moves up or

tally and moved slowly

or down.

down as indicated.

up or down, palm in di-

rection of movement.

Open hand used as if

Adjust wing position lat-

Wingman moves in di-

beckoning inboard or

erally toward or away

rection indicated.

pushing outboard.

from leader.

Hand opened flat and

I am going to dive or

Prepare to execute.

palm down, simulating

climb.

dive or climb.

Hand moved horizon-

Leveling off.

Prepare to execute.

tally above glare shield,

palm down.

Figure 26-1. Visual Communications (Sheet 4 of 9)

VII-26-4

ORIGINAL

A1-E18GA-NFM-000

TAKEOFF, CHANGING LEAD, LEAVING FORMATION, BREAKUP, LANDING (CONT)

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

Two fingers pointed to-

1. Turn IFF to

Repeat then execute.

ward eyes (meaning IFF

STANDBY.

signals), followed by:

2. Set mode and code

1. CUT

indicated: first numeral-

mode, second and third

2. 3-digit numerals

numerals-code.

Head moved backward.

Slow down.

Execute.

Head moved forward.

Speed up.

Execute.

Headed nodded right or

I am turning right or

Prepare to execute.

left.

Thumb waved backward

Series of 00s in code,

Take cruising formation

Execute.

over shoulder.

given by external lights.

or open up.

1. Holds up right (or

1. Single letter R (or

1. Wingman cross un-

1. Execute.

left) forearm vertically,

K) in code, given by ex-

der to right (or left) ech-

with clenched fist or

ternal lights.

elon or in direction of

single wing-dip.

wing-dips.

2. Same as above, except

2. Series of RRs (or

2. Section cross under

2. Execute.

with pumping motion or

KKs) in code, given by

to right (or left) echelon

double wing-dip.

external lights.

or in direction of wing-

dips.

Triple wing-dip.

Division cross under.

Execute.

Series of VVs in code,

Form a Vee or balanced

Execute.

given by external lights.

formation.

Series of zooms.

Series of XXs in code,

Close up or join up; join

Execute.

given by external lights.

up on me.

Rocking of wings by

Prepare to attack.

Execute preparation to

leader.

attack.

Rocking of wings by any

We are being, or are

Stand by for and ex-

other member of flight.

about to be, attacked.

ecute defensive maneu-

vers.

Lead plane swishes tail.

All aircraft in this for-

Execute. Leader speeds

mation form step-down

up slightly to facilitate

column in tactical order

formation of column.

behind column leader.

Figure 26-1. Visual Communications (Sheet 5 of

VII-26-5

ORIGINAL

A1-E18GA-NFM-000

TAKEOFF, CHANGING LEAD, LEAVING FORMATION, BREAKUP, LANDING (CONT)

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

Shaking of ailerons.

Long dash, given with

Execute signal; used as

Execute last signal

Head raised then low-

external lights.

required in conjunction

given.

ered.

with another signal.

Open and close four fin-

Three dashes with exter-

Extend or retract speed-

Repeat signal. Execute

gers and thumb.

nal lights.

brake as appropriate.

upon head nod from

leader or when leader’s

speedbrake extends/

retracts.

Rotary movement of

Two dashes with exter-

Lower or raise landing

Repeat signal. Execute

clenched fist in cockpit

nal lights.

gear and flaps, as appro-

when leader changes

as if cranking wheels,

priate.

configuration.

followed by head nod.

Pointing index finger

One dash with external

Landing runway or ball

Ashore: Take position

toward runway/ship in

lights.

and ship in sight.

for landing.

stabbing motion, repeat-

edly, followed by lead

Carrier: Break off and

change signal.

land.

Raised fist with thumb

How much fuel have

Repeat signal, then indi-

extended in drinking

you?

cate fuel in hundreds of

position.

pounds by finger-

numbers.

Leader lowers hook.

Letter H in code, given

Lower arresting hook.

Wingman lower arresting

by external lights.

hook. Leader indicates

wingman’s hook is down

with thumbs-up signal.

Open hand held up, fin-

Course to be steered is

Nod of head (‘‘I under-

gers together, moved in

present compass head-

stand’’).

fore-and-aft chopping

ing.

motion (by leader).

ELECTRONIC COMMUNICATIONS AND NAVIGATION

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

Tap earphones, followed

Take over communica-

Repeat signals, pointing

by patting of head, and

tions.

to self, and assume com-

point to other aircraft.

munications lead.

Tap earphones, followed

I have taken over com-

Nod (‘‘I understand’’).

by patting of head.

munications.

Figure 26-1. Visual Communications (Sheet 6 of 9)

VII-26-6

ORIGINAL

A1-E18GA-NFM-000

ELECTRONIC COMMUNICATIONS AND NAVIGATION (CONT)

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

Tap earphones and indi-

Shift to channels indi-

Repeat signal and ex-

cate by finger-numerals,

cated by numerals.

ecute.

number of channel to

which shifting.

Vertical hand, with fin-

What is bearing and dis-

Wait signal, or give mag-

gers pointed ahead and

tance to the TACAN sta-

netic bearing and dis-

moved in a horizontal

tion?

tance with finger-

sweeping motion with

numerals. The first three

four fingers extended

numerals indicate mag-

and separated.

netic and the last two or

three, distance.

VISUAL EMERGENCY SIGNALS (AIR-TO-AIR)

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

Arms bent across fore-

Horizontal motion of

General emergency sig-

Carry out squadron doc-

head weeping.

flashlight shone at other

nal meaning, I am in

trine for escort of dis-

aircraft.

trouble.

abled aircraft.

Landing motion with

Circular motion of flash-

I must land immediately. Assume lead if indicated

open hand.

light shone at other air-

and return to base or

craft.

nearest suitable field.

Point to pilot and give

Flash series of dots with Are you having diffi-

Thumbs up: I am all

series of thumbs down

exterior lights.

culty?

right.

movements.

Thumbs down: I am

having trouble.

Lights off once then on

steady: I am all right.

Lights flashing: I am

having trouble.

Figure 26-1. Visual Communications (Sheet 7 of 9)

VII-26-7

ORIGINAL

A1-E18GA-NFM-000

ARMAMENT

SIGNAL

MEANING

RESPONSE

DAY

NIGHT

1. Shaking hand, with

1. Arm or safety

1. Repeat signal and

fingers extended down-

missile/rockets as appli-

execute.

ward.

cable.

2. Followed by

2. How many missiles/

2. Indicate with ap-

question-signal.

rockets do I have?

propriate finger-

numerals.

3. Followed by

3. I am unable to fire.

3. Nod head (‘‘I un-

thumbs-down signal.

derstand’’).

Jettison external stores.

Repeat signal and ex-

ecute.

Pistol cocking motion

1. Strobe light ON and

1. Set up your

with either hand, fol-

OFF by lead aircraft.

switches for jettison.

1. Set up jettison/

lowed by fore and aft

ordnance switches.

pulling motion with a

2. Strobe light turned

2. You are cleared to

clenched fist.

ON for second time (al-

drop.

2. Execute.

low time for setting up

switches).

Figure 26-1. Visual Communications (Sheet 8 of 9)

VII-26-8

ORIGINAL

EA-18G. FLIGHT MANUAL (2008) - page 11