Originally Posted by
mad_jock
Enroute you are not using the GPS as your primary nav source. You are using it as another tool in your box. All information is required to be cross referenced to your primary nav kit ie vor's,NDB etc. And if there is a discrepency you go with the NDB,VOR's etc.
The systems that do allow you to use the FMC as primary nav source are because there is redundacy.
Would you like to describe in more detail how a VOR or NDB has "redundancy" that would motivate me to "go with it" in case of a discrepancy while ignoring a 12-channel RAIM-capable GPS?