Phugoid oscillations are slow pitch changes with which condition during the oscillation?

• A. Angle of attack remains constant
• B. Pitch angle changes rapidly
• C. Airspeed remains constant
• D. Altitude remains constant

Answer: (A)

Phugoid motion is a long-period longitudinal oscillation where the airplane trades altitude for airspeed in a slow, energy-exchange cycle. As this happens, the aircraft’s pitch attitude may drift, but the angle between the wing and the relative wind—the angle of attack—remains essentially constant. Keeping angle of attack steady means the lift coefficient stays about the same while speed and altitude rise and fall over a long period. This slow, near-constant angle of attack distinguishes phugoid motion from other modes that involve rapid pitch changes or fixed altitude or speed.