Takeoff or Landing: Which Is the Greater Challenge?

ByABC News
July 5, 2005, 11:12 AM

July 6, 2005 -- -- One of the basic rules of aviation, goes an old aeronautical joke, is that you should always log as many landings as takeoffs.

Certainly it's not a hard rule to follow. Takeoffs are volitional, but landings (of one sort or another) are compulsory, and it's all too true that in 100 years of heavier-than-air flight, we've never left one up there.

Few of us, however, have been spared the cocktail or dinner party debate over which one is the more challenging. The "takeoff" crowd can cite the difficulty of accelerating and controlling a large air machine as it makes the transition from an expensive and unwieldy tricycle with wings to an airborne thing of beauty, but the "landing" advocates can cite just as much complexity and just as many historic landing accidents.

So who's right?

Well, first let's dissect both events.

Airplanes such as large jetliners on the ground are supported by landing gear (wheels). The fuselage and wings and tail flex downward slightly (you don't notice this but large aircraft structures are designed to be reasonably flexible) when on the ramp. But in the air, the wings (and to a much smaller extent the horizontal tail surfaces) support the same structure, producing enough lift (measured in pounds) to equal and then exceed the weight of the loaded airplane at rest. The transition phase we know as a "takeoff" is that process of transferring the weight from the landing gear struts to the wings, and as we all know, that's done by accelerating a big plane down a long strip of concrete (runway) until the speed gets high enough to let the plane achieve flight.

I know this is basic, but hang with me. There's a point coming.

As the plane picks up speed, the wind flows faster and faster over the wings, and yes, thanks to a thing called the Bernoulli Effect, even with the aircraft's nosewheel firmly on the runway, the shape of the wings produces what we loosely call "lift."

But until the wings are canted upward as they ram into the wind, Bernoulli's convenient equations won't produce enough upward force to lift the plane off the runway. That's why your pilots compute a certain speed for every takeoff (based on the weight of the aircraft and other factors) at which it's the best possible time to raise the nose of the plane (and thus the wings) in order to produce that breakaway surge of lift. We call that speed VR for the Velocity of Rotation, or the speed at which the pilot "rotates" the plane's nose up.