TM 55-1510-220-MTF
PROCEDURE
TROUBLESHOOTING
REFERENCE
F.
AVIONICS FLIGHT CHECKS (CONT)
operation. HOLD key will dim.
o.
Leg Switching - Check as follows:
(1) INS - Set up for manual flyover when approaching waypoint.
(2) ALERT indicator - Monitor. (The ALERT monitor will illuminate approximately two minutes
before the waypoint is reached.)
(3) Data selector - L/L POS (when approaching waypoint).
(4) HOLD key - Depress when closest to the waypoint.
(5) Present position readout - Record.
(6) Error distance (if any) - Visually estimate between the location at which the HOLD button was
pressed and the location of the waypoint.
(7) Compare the frozen INS display of present position with the coordinates of the waypoint, taking
into account the visually observed error distance. This position error shall not exceed 1200
feet.
4-20
