What is VMC?

BTeter

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

Verified

Key Takeaways:

The published Minimum Control Airspeed (VMC) in the Pilot's Operating Handbook is an idealized value, and the actual VMC in flight varies significantly with conditions, often being much higher and more dangerous than anticipated.
Key factors dramatically affecting actual VMC include bank angle (a slight bank toward the operating engine is crucial, while banking toward the dead engine significantly increases VMC) and aircraft weight.
Allowing excessive yaw or sideslip during asymmetric thrust can lead to a dangerous vertical stabilizer/rudder stall, resulting in a rapid and often unrecoverable loss of directional control and potential spin.
Maintaining control during asymmetric flight requires precise, coordinated use of rudder, ailerons, and elevator for airspeed, coupled with the critical readiness to reduce power on the operating engine(s) if necessary to mitigate excessive yaw and prevent loss of control.

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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