Maximun is 45,000 ft under ATC, Absolute Maximun is 60,000 without special permission from the FAA
because it has been pressurised in a similar way (outcome) to how a commercial airplane is pressurised for passengers to fly at altitude.
The Blackbird
It depends on what kind of jet or commercial airplane it is.
It depends what aircraft and what speed you are going
There is no certain cruising altitude for a commercial airline. it depends on where they are flying and how long they fly. most airlines fly above 10,000 ft. the max altitude is around 41,000 ft.
an added tank
The stratosphere
stratosphere
22 hours
Above 50,000 feet (15 kilometers)
The u2 spy plane it can fly so high you and see the curveture of the earth
10 kilometers (about 32,808 feet).