In steady, unaccelerated flight, which statement about lift is true?

• A. Lift is solely determined by weight and is independent of airspeed.
• B. The angle of attack does not affect lift.
• C. There is a corresponding indicated airspeed required for every angle of attack to generate sufficient lift to maintain altitude.
• D. Lift increases only with speed, not angle of attack.

Answer: (C)

In steady level flight, lift must balance the aircraft’s weight, so the wing must produce just enough lift at the given conditions to hold altitude. Lift depends on several factors: airspeed, air density, wing area, and the lift coefficient, which in turn changes with angle of attack. Because the lift coefficient increases as you raise the angle of attack (up to the stall point) and increases with dynamic pressure (related to airspeed), there is a specific indicated airspeed needed for a particular angle of attack to generate the required lift to maintain altitude. If you fly at a lower airspeed for that angle of attack, the wing won’t produce enough lift and you’ll descend; if you fly faster, you can maintain the same lift at a different angle of attack, up to the stall limit. This is why there is a corresponding indicated airspeed for every angle of attack to sustain level flight. Lift is not independent of speed, nor does angle of attack alone determine lift without considering speed and air density, and lift does increase with angle of attack only until you reach stall.