... Airplanes are held up by the way air pressure rearranges itself when air flows over the wing of an airplane. ... With the airplane in flight, an air flow passes over the wing, and the shape of the wing's cross section--curved above, flat or nearly flat below--reduces the pressure on top, causing the extra pressure from below to exert a lifting force (" lift "). ... Then at cruising altitude, as the airplane speeds up, the wing is rotated around its pivot--one tip points forward, one back. ...