How does a jumbo jet weighing hundreds of tons stay in the air?

Hook

Why and how does a jumbo jet weighing hundreds of tons stay in the air? Thanksgiving week is one of the busiest times of the year to fly. And every flight depends on the same simple trick: pushing air down.

Forces

Four forces act on a plane. Weight pulls it down. Lift pushes it up. Thrust from the engines pushes it forward, and drag from the air holds it back. To fly level, lift has to match weight.

Wing

Lift comes from the wings. A wing is shaped and tilted so that, as it moves forward, it bends the air flowing past it downward. That tilt is called the angle of attack.

Newton

Push air down, and the air pushes the wing up. That's Newton's third law: every action has an equal and opposite reaction. A big airliner throws a huge amount of air downward every second.

Pressure

You can also see it as pressure. Air speeds up over the curved top of the wing, and faster moving air has lower pressure. Higher pressure underneath pushes up. Both explanations describe the same flow.

Myth

You may have heard that air over the top has to meet the air underneath at the back edge. That's a myth. NASA points out the air on top actually gets there sooner. Lift doesn't depend on that.

Speed

Speed matters. More speed means more air deflected and more lift. That's why planes race down the runway before takeoff, and why flaps extend from the wings to add lift at slower speeds.

Close

So planes fly because their wings push air down, and the air pushes the wings up. ThatsWhyHow.