Maybe a bit of a rethink required there Chris.
Engine failure at a couple of feet, fair enough, skid it on (at high speed, but just like a motorbike there.)
A couple of hundred feet? Deploy the parachute, you'll land happily in the playground of the kindy you were flying over, a few seconds after your hoverbike became an uninvited playmate in the sandpit.
In between? How good's your parachute at inflating from 50 feet, say?
He could just put a placard on it forbidding riding above 3 feet, though; that should solve the problem.