Alpine Flight Training provides all levels of multi-engine training. Vmc training is a standard part of our training curriculum.
What is Vmc?
Familiar to pilots of multi-engine aircraft, Vmc is the speed below which aircraft control cannot be maintained if the critical engine fails under a specific set of circumstances (see 14 CFR part 23). It is marked as a red radial line on most airspeed indicators. The blue line that’s found on many (but not all) multi-engine airspeed indicators is the Best Single Engine Rate of Climb Speed. It’s good to be at or above this speed whenever possible to give you some climb performance if an engine should fail. Vmc only addresses directional control.
What’s So Critical About It?
While you could argue both engines of a multi-engine airplane are important, the laws of physics dictate that losing a particular engine will make maintaining directional control more challenging. Any engine failure on a multi-engine airplane will result in a yaw toward the inoperative engine, but if the critical engine fails, the yaw forces will be greater due to P-factor. Engines that rotate clockwise from the pilot’s perspective (like most U.S. aircraft) will produce greater thrust on the descending propeller blades when the aircraft is flown at a positive angle of attack. Because there is a longer moment arm associated with the right engine, the yaw will be harder to manage if the left engine fails.
Practice Makes Perfect
Too often pilots will practice Vmc before their checkride, but may fall short in experience and skill when a real-world situation strikes. To stay fresh on engine failure procedures, get with an instructor and practice a Vmc demo or two. It’ll also give you chance to review some of the unsuspected conditions that can easily make a Vmc situation worse, like an aft CG, retracted gear, and/or holding wings level.