G Farris wrote:



I love GPS, and I see no problem in being highly reliant on it, because it is
intrinsically reliable - however I believe it would be practical and desirable
to build a system that maintains full RNAV capability in the event of a loss
in GPS integrity.

You're thinking in light aircraft terms. All modern air carrier jets and
biz jets have IRUs, which will provide a decent RNAV platform for a
reasonable length of time in the terminal area and for a very long time
en route.