Explain roll upset.

• A. Ice accumulation on wings may cause parts of the wings to stall and self deflect the ailerons.
• B. Roll upset occurs only with engine failure.
• C. Roll upset is a normal condition during high-speed flight.
• D. Roll upset is caused by excessive rudder input.

Answer: (A)

Roll upset is a rapid, uncommanded rolling motion caused by disruption of the wing’s aerodynamics. When ice builds up on the wings, airflow can separate unevenly—some portions stall while others still produce lift. This changes the lift distribution and can make the ailerons less effective or cause a built‑in roll moment as the stalled section drags one wing down. The result is a sudden roll toward the stalled wing that the pilot may have difficulty countering.

Ice on the wings is the key factor here because it directly alters lift and control effectiveness. The other options don’t fit because engine failure affects thrust and yaw rather than causing an abrupt roll by itself, roll upset is not a normal condition at high speed, and excessive rudder input is more about yaw and coupling than the wing stall dynamics that produce an unexpected roll.