All lights in data displays and on the mode selector unit momentarily illuminate, followed by a 10-second self-test.
Use only during alignment.
TK/GS –
Left window displays true track (course).
Right window displays present ground speed (knots).
PPOS –
Left window displays present latitude.
Right window displays present longitude.
WIND –
Left window displays present inflight true wind direction.
Right window displays present inflight wind speed (knots).
HDG/STS –
Left window displays present true heading.
Right window displays any applicable maintenance status codes.
During alignment, right window displays minutes remaining until alignment is complete. For alignments greater than 15 minutes, the window displays 15 until the time remaining reaches 14 minutes. The display then counts down in one-minute intervals.
Brightness (BRT) Control
Rotate – Adjusts brightness of the data displays.
System Display (SYS DSPL) Selector
L – Selects left IRS for the data displays.
R – Selects right IRS for the data displays.
Enter (ENT) Key
Illuminated (white) – N, S, E, W, or H entries are being keyed.
Push – Keyed data is entered into IRS following completion of valid self-test for reasonableness.
Data Displays
Two windows display data for the IRS selected with the system display selector:
Type of data displayed is normally determined by the display selector.
Keyboard entry of present position or magnetic heading overrides the selected display.
Last digit of each window is for a decimal place (tenths).
Keyboard
Push –
Alpha keys:
Data displays are controlled by the keyboard when the N, S, E, W (latitude/longitude), or H (heading) keys are pushed.
Pushing an alpha key arms the keyboard for numeric entries.
Numeric keys:
Permit manual entry of present position when ALIGN light is illuminated.
Permit manual entry of magnetic heading when either mode selector is in ATT.
Clear (CLR) Key
Illuminated (white) – An ENT attempt has failed (entry not accepted by IRS).
Push – Clears data display of any data not yet entered or accepted. If illuminated, cue lights extinguish.
