DP
That is my point and I am still trying to get my head around how an artificial setting of 1013 which bares no relationship to the actual pressure of the day can be used as a level limitation for avoiding hypoxia.
Forget 1013 lets make an artificial setting of 1040 or one of 980 why not use those? They would be as accurate as 1013? everyone could fly around in teh airways using 1040 or 980 with the push of a regulation pen.
You could be talking about a difference of 1000 feet from your flight level to your actual altitude.
Am I missing something here or being stupid?
Pace, I know you know this, but FL measures atmospheric pressure (albeit in units of feet), so it is exactly what the regs should specify
A flight level doesnt measure anything and altimeter with 1013 set will show an altitude if the QNH happens to be 1013 but will show a FL which bares no relationship to an altitude if the pressure of the day is not 1013
Pace