abc1 - do NOT forget that each pilot should be aware of the other's instrument readings - ie the odd 'cross-check' would have avoided one of the incidents mentioned here. If you have 2 of the 3 ASI's or altimeters in agreement..................It is not a bad idea to try and cover up the misleading instrument either to minimise distraction.
INS or GPS groundspeed is of no use at anything other than low level except as an indication of whether you are accelerating or decelerating. Aeroplanes fly and crash because of IAS, not GS or TAS.
If, heaven forbid, the worst happens to you -ALL sources are out - and you are sitting fat and happy with the correct pitch and power, ignoring all the false warnings and just wondering how you are going to get down, hetfield's suggestions will help a lot. Getting out over some oggin would be nice too, where the Radalt will safely give you a cross-check. After that, you need to find an ILS or PAR, hopefully in reasonable weather, which is reachable at a 'safe' altitude that you can confirm.
Don't forget - we're all counting on you...
