The fastest growing recreational sport meets the most popular form of foriegn travel.
As others have said, this is potentially a very complex subject, and becoming more so as Trimix courses become available to the recreational diver.
I do both, at a professional level, although the diving is not as frequent as it used to be.
The CAA/JAA guidelines are that 12 hours should elapse between a shallow dive and flying, whilst the diving organisations (who are more likely to end up in court) say 24 hours.
After a solid two weeks of leading dives in the 12 - 40 metre depth band, plus an occasional forray past 50 metres with friends, my Aladin computer gave me a desat time of 32 hours, with a no fly limitation of 14 hours.
I use the desaturation time rounded up to the nearest 12 hours so in the case above 36 hours before my flight home I will have packed my kit.
You may use Air/Nitrox/Trimix, do deco/non deco dives, use tables or a computer, whatever, I would suggest that you work on the safe side of when your nitrogen loading is ZERO, and if you are serious about your diving then a good computer is invaluable.
As for X ray machines reducing dive computers to scrap ? thats a new one on me, my computer travels the world and shows no ill effects.
More to the point, if you are flying, it should mean that you are completely desaturated.
Ergo the information in the volatile memory is irrelevent.