CL300
"......on when they reach 51000ft."
I take it you are a trainer of some description, line trainer maybe.
If you are cruising at 51,000ft, you are compromising on safety IMHO. What if you have a "blowout" up there? I think you would be very lucky to survive and your passengers would not have a show in hell.
In spite of what the glossy sales pamphlets state, at that altitude you are in pressure suit territory, with pressure breathing available.