Why do helicopters crash so much more often than other aircraft?
In: Physics
Depends on if they are single or dual engine.
I’d say more often than not though it’s pilots that are flying in weather they should not be flying in
Helicopters can land safely even when the engine fails. It’s called “autorotation”.
The pilot lowers the “collective” lever – the one which makes the helicopter go up and down. This results in the angle of the rotor blades changing, so that as the helicopter descends, the airflow through the rotor causes the rotor to rotate (and therefore giving the pilot control), and causing drag (slowing the helicopter down).
Helicopters don’t have much control when the engine fails, but because they can land almost anywhere, this is all the control they need – enough to pick somewhere directly below and land.
Most larger helicopters have two engines, though, so an engine failure is much less of an issue.
Helicopters have extremely poor glide characteristics. Your best case scenario for a malfunction resulting in loss of lift is a controlled crash. There are a lot of flight regimes in which you’re basically just 100% screwed in a helicopter because you simply don’t have enough velocity or altitude to make any real recovery.
Planes have a lot more options because they are much simpler machines, and most are pretty decent gliders. A small private plane that loses power at altitude can get a pretty good distance before he hits the ground. That allows for the pilot to have some time to consider the situation, attempt to recover the aircraft, or pick a good spot to land/crash.
Helicopters also tend to operate near the ground a lot more often than planes.
They don’t. Well they kind of does, but the different is really small. On average helicopter crash at around 9 per 100,000 flight hours, while the average for all type of aircraft crash at around 7 per 100,000 flight hours. So they really don’t crash that more often, especially if you compare that to other vehicle like cars. There is also less risk of death with helicopter than other aircraft, but the difference is very small. Like 1.3 vs 1.4 death by 100,000 hours. But of course that is mostly because you have a lot less people on average on a helicopter.
When a helicopters engine fails they become big metal bricks. A plane however, the shape allows for some control and the ability to glide while trying to get the engines back to working. Most planes have multiple engines as well, if one fails the others compensate. There’s no such redundancy in helicopters.
Your premise itself is incorrect. Helicopters crash less than fix winged aircraft. [Here](http://www.ihst.org/portals/54/newsletters/Facts4_Accident%20Rates.pdf) is the relevant data from 2014. It is just that there have been several high profile celebrity deaths from helicopter crashes, which makes people think they are more common.
Well they don’t crash very often. But as with most aviation incidents, especially fatal ones, the incidents are given a tremendous amount of media coverage. Car accidents are tremendously common, involving roughly 1 million crashes per year just in America, with about 30,000 deaths, but because of how common they are we barely hear about them. But an airliner crash is primetime news, often for days or week
Helicopters are famed for the vibrations that come with their big rotors. Vibrations are famed for loosening nuts off bolts, and other fasteners, and generally being a problem for mechanical systems.
Also, when things go wrong on an airplane, they have some sort of glide slope where they can manage the descent a little more gracefully than a helicopter autorotating.
Simple answer, they’re extremely unstable. Airplanes are naturally stable.
Thought experiement:Drop a 747 off a 40,000ft cliff. it will eventually nose down, increase speed, gain lift and start to pull out of the freefall.Do the same thing with a helicopter and it just hits the ground.
Thus, more helicopter crashes than airplane. This doesn’t even include the frequency of use of each of these elements in question. (which I believe would be heavily in favour of Airplanes!)
The people saying helicopters are less stable or inherently less safe than fixed-wing aircraft (planes) are mistaken. Autorotation (described by /u/jacklychi) allows helicopters to make controlled landings without an engine very easily, and helicopters get just as many safety inspections as any other aircraft, more or less, *if* they are for commercial transportation.
The biggest difference is that helicopters are used primarily for low, short flights between nearby destinations. Autorotation requires a certain height above the ground in order to work – that means if a helicopter loses and engine it’s safer if you’re *higher* up. Except that most helicopters are flying lower to the ground. That makes autorotation more difficult. And since helicopters are usually flying over populated areas it’s less likely that a helicopter will be able to find a clear, open place to land. Although autorotation allows a helicopter to land safely if it has a place to land, they still don’t have glide slopes – you’re not going to get very far, only straight down. A plane will be flying probably much higher and although a landing without an engine is more dangerous, they will at least have more energy and lift to travel horizontally to a safer, emptier place.
The tendency for helicopters to be used for lower, shorter flights also puts them closer to obstacles like power lines, buildings, birds, and even tall trees. In the case of the Kobe crash, it crashed into a hillside. Visibility was poor. Although the cause has not yet been determined, it *could* be as simple as the pilot misread the instruments and didn’t see the hillside until it was too late to avoid it. Compare that to most passenger planes which would be flying so high that not being able to see the terrain isn’t an issue, because there isn’t any. I have zero other information, I’m not saying that was the cause, I am only suggesting that it *could* be a cause which is generally not true of most commercial passenger flights.
The other problem is that helicopters are more likely to be privately owned and operated, at least compared to big passenger planes. Those are regulated *very* strictly. Although *any* flights are very regulated, a small for-hire helicopter service may not have the same stringency applied to it as other modes of air travel. This is also true of small planes, too, and one of the reasons they tend to crash more often than big passenger planes.
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