just my type of subject, studying millitary, and commercial aircraft. the only thing that could mess with it, would, yes be the turbulance, but if an airplane had enough turbulance to mess with dvd playback, then you wouldnt be messin with the laptop, ud be holdin on for life. air pressure wouldnt do squat, but, it could be the forward motion, as they do travel at about 500+ mph. but if that was it, then it would have to be constant acceleration. so my best bet would be a shotty dvd drive. weird tho, works on ground, dosent in air. on the ground is it plugged in? and what is the bat condition when in the air? dead/dying battery could do it. otherwise that, i got no idea.