T-45C TS, ADV & IUT ENG-22
CNI System Malfunctions
B. GINA GPS-INS mismatch
1. Causes
a. INS-GPS position computation disparity
b. INS-GPS velocity computation disparity
c. Disparity persists for a 3-sigma period
(1) Three sigmas equates to three (3) times the
nominal allowed deviation: a total of 24-30
seconds until cockpit displays are affected
(2) Either GPS or INS may be in error
(3) Both GPS and INS may be in error (unlikely)
2. Indications to pilot
a. ADI
(1) Barometric altitude is no longer filtered;
indications may mildly fluctuate
(2) Vertical velocity is removed from displays
(3) AV BIT advisory displayed on all MFDs in
lower right-hand corner
NOTE: AV BIT advisory may be removed from
view by selecting the BIT display.
(4) GINA DEGD is indicated on the BIT display
sub-menu
b. HSI
(1) Ground track marker is removed
(2) Groundspeed is removed
(3) Wind direction and speed are removed
Original (9-98)
Page 22-9