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Abnormal Procedures
5-17
GPSS INVALID
Failure Indication:
If the DFC-PFD system recognizes that the autopilot mode is
GPSS but the roll steering information from the GPS Nav-Com is
invalid, a yellow “
GPSS INVALID
” message is displayed on the
PFD.
Functionality Lost:
Either a flight plan has not been entered in the governing GPS
Nav-Com and GPSS mode was selected on the autopilot control
head in which case, there is no lost of functionality, or the system
is unable to fly the flight plan in GPSS roll steering due to some
anomalous GPS Nav-Com situation or the ground speed is less
than 40 knots.
Recommended Pilot Action:
Enter a flight plan into the navigator or select an autopilot mode
that is not GPSS.
Change 3