e. Fly aircraft within line of
sight of interrogating stations.
f. Contact the facility by radio
and request that the aircraft
be interrogated and that the
reply be checked for satisfac-
*17. Encoding altimeter.
Check as follows:
a. Mode C switch (transponder
control panel) - Check on
b. Contact ground radar facility
and request them to give you
Ground facility altitude read-
out must agree with aircraft
altitude within ±200 feet.
18. Radar set (RDR 1200).
Check while airborne as follows:
During the first five seconds after turning
the system on, a distinct noise and/or vibra-
tion may occur in the antenna. This is the
normal sound of the stepping drive motor
waiting for the strobe line to catch up for
a. Turn on procedure: Mode
switch - TEST.
b. Initial control settings:
(1) Wx/GAIN control - Wx.