How does VMC change at different altitudes?

The correct answer indicates that Vmc (minimum control speed) decreases as altitude increases. Vmc is the minimum airspeed at which a pilot can maintain controlled flight with one engine inoperative. It is affected by several factors, including atmospheric pressure and density.

At higher altitudes, the air is less dense, which affects the performance of the aircraft, particularly in terms of engine thrust and the efficiency of control surfaces. As altitude increases, the thrust produced by the engines typically decreases, as does the effective control authority due to reduced airflow over the wings and control surfaces. This reduction in performance means that pilots need to be able to maintain control of the aircraft at lower speeds when flying higher, thus resulting in a lower Vmc.

Understanding how Vmc changes with altitude is crucial for safe flight operations, especially during single-engine operations. It helps pilots determine the airspeed needed to maintain control of the aircraft in various flight conditions.