Peter R. wrote:

Stan Gosnell wrote:


As others have said, the GPS will still work, you just won't be assured of
enough accuracy for the approach at MDA. You will still have plenty of
accuracy for holding at the MAP holding fix, though.


I think you mean only when there is a RAIM warning does the GPS still
provide course navigation. When I experienced a GPS error message with the
KLN-94, the GPS was completely useless and needed to be recycled before it
began working again, much like a computer hard-boot.

It is also worth noting that this particular error only happened this one
time with the KLN94. Having a few hundred hours now behind a GNS430, I
have never experienced any type of GPS system error or RAIM error with the
Garmin.

The new RNAV (RNP) criteria presume a complete loss of GPS for the
missed approach. If the airspace/obstacle environment will permit a
heading or track to a VOR missed approach in the event of loss of GPS,
then no backup is required. If the missed approach areas are too tight
then dual or triple IRUs are required.

With the present RNAV (GPS) approaches the presumption is that flying
headings will get you out of the woods until you can either get a vector
or receive a VOR. There is some risk with this presumption.