There has been debate about whether lift is best explained by downwash and Newton's laws of motion or by Bernoulli's principle. The downwash theory states that an aircraft produces aerodynamic lift by deflecting air downwards. This generates an equal and opposite upwards force on the wing called lift. When the downwash force exceeds the weight of the aircraft, the aircraft will rise. Bernoulli's Principle states that the reduction of air flow on top of the wing causes an increase in air velocity and a reduction in pressure. The high pressure below the wing opposed to the low pressure above it causes lift. Modern writings agree that both Bernoulli's principle and Newton's laws are relevant and either can be used to correctly describe lift.
^ abCrane, Dale: Dictionary of Aeronautical Terms, third edition, page 172. Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2
^Anderson, John D. (2004), Introduction to Flight (5th ed.), McGraw-Hill, pp. 352–361, §5.19, ISBN0-07-282569-3
^"The main fact of all heaver-than-air flight is this: the wing keeps the airplane up by pushing the air down." In: Langewiesche, Wolfgang (1990), Stick and Rudder: An Explanation of the Art of Flying, McGraw-Hill, pp. 6–10, ISBN0-07-036240-8