PA.IX.G.K1FAA-S-ACS-6C · Nov 2023Knowledge
Factors affecting minimum controllable speed (VMC).
Factors affecting minimum controllable speed (VMC).
Bottom line
VMC is the calibrated airspeed at which, following the sudden critical loss of thrust, it is possible to maintain control of the airplane. With other factors constant, Vmc is highly sensitive to bank angle: it is reduced significantly with increases in bank angle, and it increases significantly as the wings approach level. VMC has nothing to do with climb performance, and many light twins will not maintain level flight near VMC with one engine inoperative.
Key numbers
| Number | What it means |
|---|---|
| more than 3 knots per degree of bank less than 5 degrees | Bank penalty |
| loss of directional control possible almost 20 knots above published VMC | Wings level |
| stop the turn within 20 degrees of original heading | Heading change |
| VMC plus 5 knots if no Vr published | Rotation speed |
FAA references
- AFH ch. 13 (p. 13-2) — FAA-H-8083-3C
- FAA-P-8740-66, Flying Light Twins Safely — FAA-P-8740-66
- PHAK ch. 8 (p. 8-10) — FAA-H-8083-25C (2023)
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