Illustration by Charles Floyd
The VMC demo is a multiengine checkride item that has confounded students and stressed out examiners for decades. But when done properly, it shouldn’t be dramatic at all.
The maneuver is meant to show that, with one engine on a twin at climb power and the other at idle, there’s a minimum speed below which the airplane will yaw toward the dead engine—even if the pilot is applying full rudder against it. The moral of this story: In case of engine failure, keep your airspeed up or risk losing directional control.
The reason the VMC demo worries examiners (and instructors) is that, if a student slows too much and then fails to recover, there’s a risk of an aerodynamic stall and uncommanded roll toward the dead engine—and no one wants that much excitement on a checkride.
Standards to live by
The section of the Airman Certification Standards for the VMC demonstration includes skill elements such as recovering within 20 degrees of the entry heading, as well as risk management and knowledge elements. Could you demonstrate an understanding of these required knowledge areas?
- Factors affecting VMC and how VMC differs from stall speed (VS).
VMC (red line), VYSE (blue line), and VSSE (safe single-engine speed).
- Cause of loss of directional control at airspeeds below VMC.
- Proper procedures for maneuver entry and safe recovery.
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