What is VMC?

BTeter

Monday, June 12, 2023 at 06:54 PM ET

Verified

Key Takeaways:

The published Minimum Control Airspeed (VMC) is an optimistic value determined under specific, often favorable, test conditions, and the actual VMC in flight can vary significantly and be considerably higher.
Bank angle is a critical factor: banking up to five degrees into the good engine helps lower VMC, whereas holding wings level or banking into the dead engine dramatically increases the actual VMC and the risk of a loss of control.
Allowing a large sideslip (yaw toward the failed engine) can cause the vertical stabilizer/rudder to stall, leading to a rapid and potentially unrecoverable loss of directional control and spin.
Pilots must be prepared for much more aggressive control inputs and be ready to reduce power on the operating engine(s) to maintain control in an engine-out scenario, as real-world VMC events are far more critical than typically portrayed in basic training.

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While the Pilot’s Operating Handbook shows V_MC for the aircraft, the V_MC in flight varies depending on many conditions. It’s similar to the published stall speed vs. the stall speed for your current load factor. Remember, you can stall the aircraft at any airspeed but only at one angle of attack. The same is true of loss of control during asymmetric flight, which can occur at any airspeed. When you lose an engine in a twin, the difference between the published V_MC and the actual V_MC for your conditions is critically important.

Published VMC