TM 1-1510-224-10
(d)
CLR/TST.
When
clear/test
is
selected, all memory of past strikes and symbols are
erased. After 3 seconds the system enters the test mode.
In the test mode, simulated lightning signals are fed
into the test loop in the antenna and a lightning strike is
simulated-at a bearing of 45 degrees at 25 nautical miles.
A lightning alert is also generated along the outermost
range ring at a bearing of 45 degrees. This simulated
strike will progress in severity through level three within
15 seconds of entry into the test mode. If the mode
selector is left in the CLR/TST mode, the alert and strike
symbols will reduce in severity and disappear. The
lightning rate symbol will disappear after approximately 2
minutes.
NOTE
The lightning sensor system antenna
is used in this test, and as a result,
any real lightning activity that occurs
while the test is in operation may
also be displayed.
(8)
Radar system mode selector switch.
(a)
OFF. Turns the radar system off.
(b)
SBY. Places the radar system in
standby. This is a ready state with the antenna scan
stopped, the transmitter inhibited, and the memory
erased. STBY will be displayed on the EHSI.
(c)
WX. Selecting WX places the radar
system in the weather detection mode. WX (green) will
be annunciated on the EHSI. The system is fully
operational and all internal parameters are set for enroute
weather detection. Automatic or variable gain control
may be used. Radar display levels are depicted in four
colors as described in figure 3-31. If WX is selected prior
to the expiration of the initial system warm-up period
(approximately 45 seconds),
WAIT (green) will be
annunciated on the EHSI. In wait mode, the transmitter
and antenna scan is inhibited and the memory is erased.
Upon completion of the warm-up period, the system will
automatically switch to WX mode.
(d)
GMAP. Selecting GMAP places the
radar system in the ground mapping mode. The system
is fully operational and all internal parameters are set to
enhance returns from the ground and reduce returns from
weather targets.
CAUTION
Weather
type
targets
are
not
calibrated when the radar is in the
GMAP mode. Because of this, the
pilot should not use the GMAP mode
for weather detection.
As a constant reminder that GMAP has been
selected, the GMAP legend is displayed and the color
scheme is changed to cyan, yellow, and magenta. Cyan
represents the least reflective return, yellow is a moderate
return, and magenta is a strong return. If ground mapping
is selected prior to the expiration of the warm-up period
(approximately 45 seconds), a white WAIT legend will be
displayed. In the WAIT mode, the transmitter and
antenna scan will be inhibited and the memory is erased.
Upon completion of the warm-up period, the system will
automatically switch to the GMAP mode.
(e)
FP. Selection of the FP position
places the radar system in the flight plan mode permitting
the display of navigation data on the EFIS with radar data
omitted. This position allows an extended MAP display
range (up to 1200 nautical miles) to be selected for
navigation data.
(f)
TEST. Selection of TEST position
selects test mode and puts a test pattern on the screen to
verify system operation. TEST will be annunciated on the
EHSI in the radar mode field. TEST mode is inhibited
when system is in forced standby mode.
(9)
Radar receiver gain control. This control
(placarded GAIN, MIN MAX ) is used to adjust receiver
gain when gain is variable. Pulling out on gain control
makes gain control variable. A fully automatic gain
control is provided when the gain control is in the preset
(pushed in) position.
b.
Weather Radar Normal Operation. Radar turn-on
procedure.
1.
Radar system mode selector switch OFF.
2.
Radar receiver gain control Preset (pushed
in) position.
3.
Antenna tilt angle control +15 degrees.
4.
Weather (WX) pushbutton selector switch
(display
controller)
Depress
to
select
weather display mode on the EHSI.
5.
Radar mode selector switch SBY or TEST.
3-83
