Is it permissible to don the ihram garments and make the intention for ihram at home, and to stipulate that the ihram will commence on the airplane a period of time after its departure?

If you made the intention for ihram (definition) before boarding the plane and then stipulated a condition, your ihram is valid, and the stipulation is null and void.

If you made the intention for ihram and stipulated a condition at the same time while on the plane, either at or before passing the miqat (definition), then both your ihram and your stipulation are valid.

Whoever enters into ihram before the miqat becomes a muhrim, by the consensus of the scholars.

If you entered into ihram after the plane has passed the miqat, you are obliged to return to the miqat to enter into ihram from there. Otherwise, you must slaughter a sheep and distribute it among the people of the Haram (definition).