if you can, go to a seminar, that the royal institute of navigation run, very interesting, in a nut shell, every single person who spoke, summed it up with,
GPS as a back up ONLY, never ever, get to rely on it !
Never in the history of navigation is so much bo11ocks spoken by so few to so many as in a lecture by the RNI. I've been to one of them; the old boy spent an hour explaining what a DOP was...
What really amazes me however is how many obviously intelligent people on the flying scene buy into this anti-GPS stuff.
Sure, a GPS can pack up. I've had the panel mount one pack up, on the ground, and had to fly VOR/DME/vectors for 700nm all the way home. No big deal at all. I had a couple of backup GPSs which worked but not much good for airways. A VOR or DME could pack up just as easily; the difference is that somebody will just have a moan and get his cheque book out whereas with a GPS he tells everybody about it, as some sort of apocalyptic warning of impending doom for all things that get airborne.
But the most amazing thing is who finances these wonderful olde English institutes, with their grand buildings in London full of old master paintings of their past famous chaps dressed up in fancy coats and collars and stockings and high heeled shoes (they'd do OK in certain bars in Brighton which I have dropped into by mistake) ... all the way back to Isaac Newton (who was truly brilliant).