To maintain altitude during a turn, the angle of attack must be increased to compensate for the decrease in the vertical component of lift.

• A. Decrease angle of attack.
• B. Increase angle of attack.
• C. Increase engine power.
• D. Decrease bank angle.

Answer: (B)

In a level turn, lift must balance the weight of the airplane. When you bank, the lift vector tilts toward the horizon, so the vertical component of lift decreases. To keep the aircraft from losing altitude, the total lift must increase enough so that its vertical component equals weight again. Since the vertical component is L cos(bank), you need a larger lift L, which you achieve by increasing the angle of attack (within the limits before stall). Increasing angle of attack raises the lift coefficient and, at a given airspeed, increases lift to offset the loss from banking. Power changes can affect speed and lift indirectly, but the direct way to maintain altitude during a turn is to increase the angle of attack.