Knox pauses. He has a very vague idea. But he is no scientist.

"Um, there's a very strong engine that pushes, I think, and it has wings, like a bird only not like a bird, and it...

"Shufti, all I know is that it has something to do with something pushing it and air currents. Other than that, I just let the pilot do his job, and hope my luggage doesn't go to Omaha."