DevonDiver
N/A
One thing I find intersting is that the OP is asking specifically about computers for nitrox dives. Why not all dives?
Probably because MOD is a mystery to non-nitrox trained divers... and the OP (and many others) have never even contemplated diving deep enough that the MOD for 21% would be an issue...
Is MOD A.) unimportant for air,
For recreational divers, with an abaolute recommended max depth of 40m, yes.
B.) easier to remember than for nitrox, or
I doubt it differs. But you wouldn't mark an MOD on your tank for an air-fill.
C.) is it deeper that you'll go?
I reckon this hits the nail on the head.
Plan your dive including a "this is as deep as I'll go" parameter. Regardless of whether it's most severely limited by deco, gas supply, gas contents, etc., remember the most severe limit.
Yep... that's the max depth used in dive planning. Not the max operating depth used in conjunction with ppo2.
As others have said, if you were going deep enough to worry about the ppo2 of air then you would know how to plan that dive. If you didn't then Darwin's Law covers it.