Calm down to a panic. All I said was I don't have as much faith in it as yourself. In my experence its not as good as your experence.
Still use it everyday at work.
But hey I am only a commercial pilot and have never had the fancy GPS you have, just an old trimble to play with mostly.
INS is a slighty different beast being totally internal to the airframe. With redundacy built in with 2 if not 3 units all cross checking each other and also cross checking using DME crosshatches.
And its a legal requirement you must be within 5 degrees of the final approach track according to the RMI before commencing your decent on a NDB approach. I don't have a clue if the CAA has deemed the risk of the INS all wandering off without indicating a failure in the final approach phase is low enough you can ignore the RMI.
I have never heard of anyone who is allowed to do that when there is a difference with the GPS and the RMI you follow the RMI.
As you well know its a politcal policy more than anything. Until it stops being one, the regulation stops you ustilising GPS to its full manner. There are european boffins that know alot more about the risk assesment than us are saying it isn't good enough at the moment with the lack control over it that Europe has. Any Mil flight can at the moment jam GPS with out telling anyone. FRA are payed to do it whenever there is an exercise on. Until the regulations change so they can't there is still a risk so we have to use stuff they can't fanny about with.
Here is a link to the real stats on whats happening with the GPS network and its errors from the stats
http://www.schriever.af.mil/GPSSUPPORTCENTER
And you can see by the Advisories that they are having a fair few problems. I bet the shuttle not flying has set back there update program somewhat. The page shows that atleast 5 out of the 24 sats are out of action and thats just this year. Not much error so far but... all it would take is a few more and..
MJ