DURING CRUISE (CONT)
Register/zeroize switch - Select desired fill
OFF/ON/TD switch - ON
(interrupted tone should be heard in headset).
Microphone switch - Press
momentarily (interrupted tone in headset
Microphone switch - Press (do not talk).
When beep is heard in headset, conduct two
way communication check.
Check the following modes of operation:
(1) Aircraft and ground station-
both in CIPHER mode, operating the air-
craft and the ground station each in turn, as
the transmitting station.
(2) Aircraft and ground station in PLAIN mode,
operating each in turn as the transmitting
(3) Aircraft in CIPHER mode, and the ground
station in PLAIN mode, operating the
ground station as the transmitting station.