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Comment by Gaussian | Hacker News Reader

What's amazing to me, especially after seeing these few photos of wreckage, is that everybody inside got away alive, according to the Pentagon. Intuitively, I've always thought that any helicopter crash = death sentence. Clearly, that's not true.

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Odds are the helicopter hit a tail rotor on a fence or some such thing, and had a relatively uneventful landing, even though it was too damaged to be used for extraction.

Helicopters can quite easily land if they lose power, etc., through a process called autorotation.

It was the explosive charges that were set and detonated before the team left that did the vast majority of the damage.

I landed my AH-64 Longbow using autorotation many times in the late-90s Janes simulator. I really wish somebody would come out with a good battle helicopter sim again.

DCS Black Shark is an excellent PC sim. Recommended, plus available on Steam too.

http://www.digitalcombatsimulator.com/en/series/black_shark/

(Also, check out the A-10 sim too - it's from work they did with the US National Guard Air wing as a training simulator).

Interesting story of the two Aérospatiale Lama world records:

"On 21 June 1972 a Lama with a single pilot (Jean Boulet) aboard established a helicopter absolute altitude record of 12,442 m (40,814 ft), immediately followed by an inadvertent record for the longest ever autorotation when the engine flamed out at the peak altitude of the flight."

(from wikipedia)

Always reminds me of the saying: "there are no good helicopter pilots, there are only old helicopter pilots".

I've heard it is easier to auto-rotate from a high altitude than an extremely low one.

There is a "dead man's curve". If you're low enough, you can survive a pure drop. If you have enough forward speed, you can turn that into lift. If you're high enough, you can get enough rotor speed to turn that into enough lift to slow down the drop. But there are areas in the height/velocity equation where you probably die.

Chart at http://en.wikipedia.org/wiki/Height-velocity_diagram

According to the official explanation, it didn't crash, it was forced to land, and was subsequently destroyed by the crew and passengers.

Helicopters can autorotate down in event of engine failure or tail rotor failure:

http://www.helicopterschoollist.com/autorotation_helicopter....

It didn't crash persay. It had problems generating lift and the pilot had to land it during the raid. The military then destroyed it into into the current state you see now. Usually they do this to prevent people from reverse engineering the technology and stealing it.

Yeah, helicopter crashes are generally not fatal. Shock absorbing seats, an airframe that's designed to absorb impact energy, plus the autorotating main rotor that slows down the descent like a whirlybird toy. Some of Kamov helicopters, as mentioned, feature ejection seats. What's interesting is that explosively-ejected rotor blades. The blades have enough rotational inertia to intercept the crew's ejection path if they were just released at the hub.

I always thought the opposite...since you can't eject from a helicopter, I always thought (and pretty sure I've been told) they are built to maximize survivability during a crash. There were survivors to both downed black hawk in Mogadishu.

The Russian Ka-50 Black Shark attack helicopter has an ejection seat for the pilot. According to Wikipedia, the rotor blades and canopy are blown away by explosive charges before the ejection seat is triggered.

IIRC the Eurocopter Tiger also has this feature.

Nope, it doesn't. The Ka-50 is the only production helicopter to be equipped with an ejection seat.

Part of the reason other attack helicopters don't have them is that ejection seats in helicopters add complexity and weight for not that much of an increase in survivability, considering the usual flight profiles that these helicopters fly.

It makes more sense to focus on improving the survivability of crashes through measures such as collapsing seats and landing gear designed to absorb impact forces. With these types of improvements the crew of modern helicopters can survive even severe accidents without serious injury.

OK, fess up, who else thought that the Tigre had an ejection seat because they saw it in a James Bond movie?

From what I've read, there wasn't a "crash", per se. There was a mechanical failure that was serious enough to require an emergency landing. The pilot landed the helicopter and then the team destroyed it. The wreckage that we see is the result of the team destroying the helicopter, not of the landing itself.

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