Originally Posted by
n5296s
That's a new one to me. I've never heard of an IRS approach. Do you get a penalty if you go below minimums? Can it be audited?
On my aircraft the assumed ADIRU drift if GPS is lost is 8 NM per hour. If you’re already on an RNAV approach when you lose GPS, it’s perfectly feasible to complete the approach before you get NAV UNABLE RNP.