Multi-Engine Ground School Part 2! - VMC

Now, VMC is defined as the minimum control airspeed with the critical engine inoperative, all right? This is the speed at which, should you reach it, We no longer have enough control effectiveness or authority to keep the airplane under control.

And specifically, we're talking about our rudder.

It's when essentially our rudder has been used up to its fullest extent.

There is no more rudder to give, typically right rudder if our left engine is critical as it usually is.

And essentially the rudder stalls.

You don't have anything else to give.

It reaches a critical angle of attack.

It becomes ineffective.

You can no longer control the aircraft.

And we go into what we call a VMC roll.

Now, while that may sound fun, I assure you VMC rolls are not what we want to experience at any point when we are in a multi-engine aircraft.

Basically, a VMC roll is going to lead you into a spin of sorts.

And the dangerous thing about spins in multi-engine aircraft, and the reason why there are really no multi-engine aircraft that I'm aware of that are certified for spins, is because with multi-engine aircraft, we have... a whole ton of mass towards the outside, the outboard sections of the airframe, right? We've got two large engines outboard on the wings, and most multi-engine aircraft, or many, I won't say most, but many multi-engine aircraft have even further sections of mass out on the wingtips in the form of fuel tanks.

that is a lot and really a majority of the weight of the aircraft that is outboard from the center of gravity.

And what that causes when we entered a rotational state, just like a figure skater, if they put their arms out, they're gonna spin slower.

They bring their arms in, it's gonna spin faster.

When we have all of that mass outboard, it's really hard to stop the rotation from happening.

And ultimately, if we were to enter an aerodynamic spin in a multi-engine aircraft, it's going to quickly change from an aerodynamic spin into an inertial spin.

And there is no rudder on any aircraft that is large enough and effective enough to stop an inertial spin once it has started.

So that's why we take VMC very seriously.

And the VMC demo, which you can see me demonstrate here in this video, if you're watching on YouTube, is the most critical and kind of high-risk maneuver, the most dangerous maneuver you will ever do in regular flight training.

So we take it very seriously.

All right, so that's VMC.