VMC terminology question

Posted by Icy-Bar-9712@reddit | flying | View on Reddit | 16 comments

Was talking about a twin crash where the engine failed on take off. He was adamant that would be a VMC demo. My understanding is a VMC demo is an intentional maneuver, and an engine loss on takeoff and not getting the prop feathered and flipping it over would be a LOC from engine failure? This guy was *D*efinitely *P*retty *E*xcitable over the whole thing so I really wasn't in a postion to argue, but just wanted to make sure I understood the terminology.

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16 Comments

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Accomplished-Ice-604@reddit

In a real engine failure, you don’t want to get anywhere near Vmc! Vmc demo is just a demo, under very specific circumstances, and no startle factor.

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Mikec2006@reddit

What speed do you fly on one engine, if not “anywhere near Vmc”?

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HailChanka69@reddit

Usually the Vyse (best rate of climb single engine) or higher. Also depends on the plane

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flyingron@reddit

It's sort of like demonstrating a departure stall right after you leave the ground. It's not supposed to be intentional in that situation.

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spacecadet2399@reddit

It's a pretty bad "demo" if you crash the plane while doing it... That's not a VMC demo, but it's an example of what happens when you're below VMC. I guess you could consider it a VMC demo for everyone \*outside\* the plane. Definitely not what the FAA's looking for in the commercial multi-engine ACS entry for the VMC demo, though.

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Low_Sky_49@reddit

The “Vmc demonstration” you have to do on your checkride demonstrates that you can control the aircraft at near-Vmc speeds and safely recover from an impending stall or loss of directional control with a simulated windmilling inoperative engine. A Vmc roll is what happens if you don’t apply that recovery in a real world excursion below Vmc with OEI. I suppose that Vmc rolling an aircraft before crashing it is a kind of Vmc demonstration, but it’s not the one the FAA wants you to do on your checkride.

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Icy-Bar-9712@reddit (OP)

Yeah, we're short enough on DPE's without thinning the herd further. He's a super smart guy and I love him to death, I think he just got roll and demo conflated and I didn't know enough to correct him, so just nod and smile.

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lnxguy@reddit

Vmca demos are done at altitude after clearing the area. LOC due to rollover by not properly responding to an engine failure should not be associated with Vmca.

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ASAPdUrmom@reddit

Demo = demonstration Vmc roll = loss of control Guy sounds like a moron

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hawker1172@reddit

Guy is probably smart while OP is misinterpreting him. Sounds like he’s making an indirect comparison. Obviously it wasn’t a demo.

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Icy-Bar-9712@reddit (OP)

No, the dude is super sharp, but there were a couple other areas where terminology seemed to have been conflated during our discussion. But in those cases I knew enough to have been able push back. I haven't done my multi yet so I'm not super knowledgeable on those items.

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ASAPdUrmom@reddit

Man that's some inception kind of shit there.. bum bummbum bummm waaaaaa bummm waaaa

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hawker1172@reddit

Yeah you just aren’t understanding his phraseology. Of course it’s not a “Vmc demo” but it’s a loss of control also known as a “Vmc roll” which is what you train in the “Vmc demo.” They’re just making an indirect comparison and the person you’re talking about likely knows that.

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Icy-Bar-9712@reddit (OP)

Ok, knowing this guy as I've done a couple, uh, "events" with him already, this is the likely answer that those two things are just the same thing in his head.

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hawker1172@reddit

If so, let him do him then lmao. Anyone with a brain knows that someone crashing an airplane isn’t doing it for demonstration purposes.

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rFlyingTower@reddit

This is a copy of the original post body for posterity: --- Was talking about a twin crash where the engine failed on take off. He was adamant that would be a VMC demo. My understanding is a VMC demo is an intentional maneuver, and an engine loss on takeoff and not getting the prop feathered and flipping it over would be a LOC from engine failure? This guy was *D*efinitely *P*retty *E*xcitable over the whole thing so I really wasn't in a postion to argue, but just wanted to make sure I understood the terminology. --- Please downvote this comment until it collapses. --- I am a bot, and this action was performed automatically. If you have any questions, please [contact the mods of this subreddit](https://www.reddit.com/message/compose?to=/r/flying).