747-400 FMC Radio Update Rejection Criteria
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747-400 FMC Radio Update Rejection Criteria
Gentlemen...
If the 3 IRU positions agree with each other, but not with a radio location (e.g. DME-DME), will the FMC reject the radio update?
Would the same apply to GPS?
A long time ago, I vaguely recall reading something about the IRU's still having the final say if there was a large discrepancy between IRU and radio position, even though the FMC position is heavily biased towards radio updating.
Things might have changed, however. Doesn't the FMC now know how accurate the GPS signal is? (ANP value)
Thanks
Regards
NSEU.
If the 3 IRU positions agree with each other, but not with a radio location (e.g. DME-DME), will the FMC reject the radio update?
Would the same apply to GPS?
A long time ago, I vaguely recall reading something about the IRU's still having the final say if there was a large discrepancy between IRU and radio position, even though the FMC position is heavily biased towards radio updating.
Things might have changed, however. Doesn't the FMC now know how accurate the GPS signal is? (ANP value)
Thanks
Regards
NSEU.
