If a human can breathe, then you are low enough to fly.[8D] (this is ment to make you laugh)

10,000 feet is aprox 50% of sea level air pressure.

Did you state an airplane will fly at about 75% ?

If so then your heli will be about the same.

aim for a high performance heli, such as the Trex 600e like I own. It has massive power .......and you don't have a fuel needle to adjust either...

Harry