Lighting Strokes Required per Symbol
vs. Range to Storm
receiver is inhibited by the XMIT INH input during
transmission by communications transmitters. No
lightning may be received during this condition.
LH/H (green). Indicates that heading
input has been deselected by the HDG VALID input.
LX/C (green). Indicates that the
system is in the self-calibration mode. This will revert to
the selected mode approximately 10 seconds after
power has been applied.
LX/I (green). The number of computed
lightning rate symbols exceeds the capability of the
(10) LX (green). Indicates that the system
is in the normal operating mode.
If two or more of the above situations are
true at the same time, the annunciation
which is highest on the above list will be
Lightning Rate of Occurrence Symbols
Self Calibration Mode. During approximately
the first 8 seconds after power is applied, the system
performs a self-calibration process to cancel out
variations in antenna gain and cable loss (LX/C will be
displayed on the EHSI). As soon as this is complete,
the letter C will be removed from the display. If strong
interfering signals outside the aircraft, or equipment
malfunction prevent the calibration of the system, it will
revert to preset calibration factors, in which case the C
will not be removed from the display. In this case the
operator should select the TST mode and evaluate the
test display. Interference signals can be caused by
other systems on the aircraft, by adjacent ground
installations such as power transformers, or by nearby
aircraft. If sources outside the aircraft cause the C to
remain displayed, they will not be present after takeoff,
and the LSS mode selector switch should be switched to
OFF and set back to the LX mode to force recalibration
for greater accuracy. If the C display persists after
takeoff, TST mode should be selected again to re-
evaluate the system.
Range switches (radar control panel, fig.
3-29) - Select range of 50 nautical miles
Lightning sensor system (LSS) mode
selector switch (radar control panel) -
CLR/TST. Verify that all lightning rate
symbols are erased from display.