the CRT display on the instrument panel as an
individual discharge point (+).
b. Controls and Functions.
(1) Power/Brightness Control. Rotate to turn
on the system and adjust the brightness of the display.
(2) Selector Buttons. The specific function of
each button is displayed adjacent to the button in each
c. Normal Operation.
(1) Self-Test. Each time the system is turned
on it will automatically cycle through a series of self-
tests which ensure that all major functions are
approximately 15 seconds to complete, check antenna
reception, processor circuitry calibration, memory and
microprocessor function, and proper operation of the
options. After proper operation has been verified by
the self-test program, a confirmation message, ALL
TESTS ARE OK, will display in reverse video. This
message will remain on the display for approximately
3 seconds and then will be replaced automatically with
If the system fails any of the internal tests, an
error message will appear indicating which test failed
and which functions may be inoperative. In most
cases, all other systems will continue to operate. If
continued operation is possible, the message, PRESS
ANY KEY TO CONTINUE will display.
When initially turned on, the system may
complete its self-test program before the CRT comes
on. In that case it is possible that the first message
that will be seen is the main menu. This is normal
If the weather screen is selected immediately, it
is possible the advisory message FLAG will display
where heading information is normally displayed. This
usually means the gyro system has not yet come up to
speed. FLAG should be replaced with heading
(2) Main Menu. The main menu provides
access to the two weather mode views and additional
information, options, and navaid display. To select a
specific menu item, press NEXT button on the display
until the desired item is highlighted and press the GO
button to view the selected menu item.
(3) Weather Modes. Two weather mode
views are available from the main menu by pressing
either the 360° or the 120° button. The symbol Ü
means to "go to." When the weather mode is initially
selected, it will always be in the 200-nm range.
Pressing the button beside the range setting will cycle
through the additional range selections from 200 nm to
100 nm to 50 nm to 25 nm and back to 200 nm. The
25-nm range is indicated by a solid ring to advise of
close proximity to potential thunderstorms. Either view
can be selected from the main menu or the opposite
view. When changing from one view to another, the
range remains constant.
The 120° view provides an expanded view so
thunderstorm information is displayed in greater detail.
Refer to Figure 3B-154.
Figure 3B-154. 120° Weather Mode
Press the CLEAR button to erase all weather
data from the display and system memory. The
intensity of a thunderstorm can be identified by the
speed with which the discharge points appear. The
system continually receives and processes new
electrical discharge information. Monitor this by
pressing the clear button often. The more intense the
storm, the faster the discharge points reappear.
Multiple discharges which appear as clusters are
indicative of thunderstorm activity. A large number of
discharge points indicate a faster rate of occurrence
and, therefore, a more severe thunderstorm. Fewer
necessarily, weaker, cell. Thunderstorm conditions
change rapidly and monitoring their activity over a
period of time by use of the CLEAR function is
recommended. Any grouping of discharge points
within the 25-nm range is cause for immediate