muff528 writes:

If that's as high as your airplane will go you probably should get another
airplane. At least don't fly around out west where the hills are higher than
that. Sometimes even the ground is higher than that! :-)

I try to avoid the mountains when flying a small plane. There are some
extensive flat areas in the American west, but it is true that sometimes to
get between two points it's hard to avoid the mountains, short of crossing
half the continent to go around them. Even if the aircraft has the requisite
ceiling, carrying oxygen for everyone is awkward and will not inspire
confidence in passengers.