That still doesn't explain the owner of the aircraft smoking in the back with no apparent effects )
Ok roughly 17 K not 20K
It also brings up a disparity between FAA and EASA
FAA it is up to 12500 feet unlimited 12500 to 14000 for 30 minutes 14000 and above all the time on oxygen for pilots! But wait for it PAX don't have to use oxygen till 15000 feet ASL
Pace