T-45C TS, ADV & IUT ENG-20
Flight Instruments Malfunctions
c.
Potential navigation problems due to heading errors
d. Instrument approach capabilities degraded due to heading
errors
e. You must use standby compass
E. Incongruent GINA GPS-INS positon and/or velocity computations
1. Causes
a. INS-GPS position computation disparity
b. INS-GPS velocity computation disparity
c.
Disparity persists for a 3-sigma period (three "sigmas" equates
to three [3] times the nominal allowed deviation period;
24-30 seconds)
(1) Either GPS or INS may be in error
(2) Both GPS and INS may be in error (unlikely)
2. Indications to pilot
a. ADI
(1) Barometric altitude is no longer filtered, meaning indications
may mildly fluctuate
(2) Vertical velocity is removed
(3) AV BIT advisory are displayed on all MFD's
(4) GINA status DEGD on the BIT display page
b. HSI
(1) Ground track marker is removed
(2) Groundspeed is removed
(3) Wind direction and speed are removed
(4) All time-to-go data is removed
(5) AV BIT advisory are displayed on all MFDs
(6) GINA status DEGD is indicated on the BIT display page
Original (9-98)
Page 20-5
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