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Helicopter safety

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Helicopter safety

Old 8th Jan 2021, 13:43
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Helicopter safety

Hi all! First post here from a long time helicopter enthusiast looking for thoughts from professionals...

Just wondered if you anyone could offer insight in helicopter safety worldwide. Someone I know tweeted that an helicopter that recently made an emergency landing was very lucky as when something mechanical goes wrong with helicotpers they normally "drop out of the sky", hence why they have to follow waterways where possible in the UK.

He also added that stats for helicopter crashes were "way worse" than for planes...

From what I've read, it's simply not true that they almost always drop out of the sky (they can do in case of tail rotor issues, but in other cases you can use autorotation and other forms of emergency landings), but they fly over water where possible because they fly low and can't glide as far. And I also read 3/4 of crashes are survived.

As for stats, I read that in the U.S., airliners aside, helicopters are actually slightly safer than small planes. And even when comparing helicopters to general aviation stats (so including airliners), it seems helicopters are only slightly worse, not way worse. Didn't find stats for Europe but can't imagine it'd be that different as to be "way worse". Apparently his mate is a UK transport lawyer and told him that helicopter safety is "horrific".

Wonder what your thoughts were? 😀
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Old 8th Jan 2021, 14:45
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The numbers per flight hour for helicopters are somewhere between commercial airlines and private small planes. If you go by traveled passenger miles there is a huge difference between commercial airlines and helicopters.

However there are also differences between helicopter operators. Large operators generally have better safety stats than small ones (better organsiations for maintenance and training). North America, EU, Japanese operators have better safety stats than South America, Eastern Europe, Central Asia and Afrika. These differences can be more than 100 fold in the statistics.

There are particularily dangerous flight regimes (hover in intermediate altitude above ground, hover in the mountains, landing in urban areas or on slopes) that are simply not possible with fixed wing aircraft. Therefore safety comparisons are even more difficult.

Landing with failed engines is possible with so called autorotation. This can be even possible with failed tail rotor, if there is sufficient forward speed and the stabilizer provides antitorque. This means in similar flight conditions where a fixed wing aircraft can land, a helicopter can land, too. However the gliding distance is much shorter.

Flying low is more dangerous than flying high and waterways are dangerous places to land with a helicopter.

I can't remember the exact numbers but way more than 3/4 of crashes are survived (probably depends on the definition of "crash").

If you want to see horrible safety stats then look for ultralight and Paragliding.
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Old 8th Jan 2021, 15:10
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Thanks! So that broadly confirms what I had read. I assume US and Europe safety is quite similar?

With regards to autorotation, I had previously read this was taught to all new pilots as basic training (land with engines shut off), and is apparently even easier to learn than hovering. However the person I was talking to said in real life scenarios, "the number of successful auto-rotates performed is in single figures" and "in reality helicopters fall out of the sky". Is this true?
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Old 8th Jan 2021, 18:43
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Originally Posted by MichaelArchangel View Post
With regards to autorotation, I had previously read this was taught to all new pilots as basic training (land with engines shut off)
The US Private Pilot Rotorcraft Practical Test Standards require the applicant to demonstrate their ability to autorotate. Per page 1-18:

B. TASK: STRAIGHT IN AUTOROTATION REFERENCES: FAA-H-8083-21; POH/RFM.
Objective. To determine that the applicant:
1. Exhibits knowledge of the elements related to a straight in autorotation terminating with a power recovery to a hover.
2. Selects a suitable touchdown area.
3. Initiates the maneuver at the proper point.
4. Establishes proper aircraft trim and autorotation airspeed, ±5 knots.
5. Maintains rotor RPM within normal limits.
6. Compensates for windspeed and direction as necessary to avoid undershooting or overshooting the selected landing area.
7. Utilizes proper deceleration, collective pitch application to a hover.
8. Comes to a hover within 200 feet of a designated point.

For a commercial rotorcraft certificate the standard is within 50 feet of a designated point.

, and is apparently even easier to learn than hovering.
Depending on the pilot it can be easier, the same, or harder. For me it was easier.

However the person I was talking to said in real life scenarios, "the number of successful auto-rotates performed is in single figures" and "in reality helicopters fall out of the sky". Is this true?
Total nonsense. As usual, successful auto's don't make media headlines. All the media prints is that a helicopter made an emergency landing. They don't wax poetic about whether it was due to an autorotation or not. But if a helicopter crashes, then it automatically "fell out of the sky".

Helicopters only fall out of the sky if the pilot allows the helicopter to lose rotor RPM below a certain value, which can happen even in powered flight where nothing at all is wrong with the helicopter, or the helicopter undergoes a dramatic mechanical failure (loss of a main rotor blade, loss of a tailboom which can happen for a variety of reasons, etc.). Low RPM accidents are, unfortunately, not all that rare, and are a failure of pilot decision making and/or technique. Serious mechanical failures like shedding a rotor blade, while dramatic like the crash of an airliner, are similarly exceedingly rare.

It is probably fair to say that some (many?) emergency autorotations often result in damage to the helicopter, typically a rollover on touchdown, which may be due to the unavailability of suitable terrain or poor technique. If the day ever comes for me where I have to perform an autorotation in anger, all things being equal I'd rather roll one at touchdown due to a failure of my piloting technique than "fall out of the sky". The first is eminently survivable, the latter is not. Not to say that my intent would not be a perfect autorotation, because it certainly will be!
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Old 8th Jan 2021, 18:55
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Originally Posted by aa777888 View Post
it can be easier, the same, or harder. For me it was easier.
Thing is, we all know we can hover because we do it often.
On the other hand most pilots have only ever practiced autos and are yet to find out if they are any good at it.
Good news is the Robbie drivers will probably find out first
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Old 8th Jan 2021, 22:39
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Most accidents are from people doing autos in training, but the real autos are relatively rare.

In 15,000 hrs I would have done thousands of practice autos, but NEVER in 45 years had a real auto or even an engine problem.
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Old 8th Jan 2021, 23:24
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Good points, all (except for the Robbie crack ). I was answering the question about what was easier for me to learn. But you are absolutely right, BR: after the initial learning period we hover all the time but rarely autorotate.

Personally I make it a point to grab an instructor and practice autos quarterly, rather than be one of those pilots that only does them during a biennial flight review. By shear coincidence, I'll be doing my first quarter 2021 practice tomorrow.
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Old 9th Jan 2021, 09:17
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Originally Posted by MichaelArchangel View Post
Hi all! First post here from a long time helicopter enthusiast looking for thoughts from professionals...

Just wondered if you anyone could offer insight in helicopter safety worldwide. Someone I know tweeted that an helicopter that recently made an emergency landing was very lucky as when something mechanical goes wrong with helicotpers they normally "drop out of the sky", hence why they have to follow waterways where possible in the uk😀
I must have been doing it wrong all these years I will need to look out for a waterways then
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Old 9th Jan 2021, 09:40
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To the OP: it would appear that the Twitter account that you saw is based on the principle of ‘a little knowledge is a dangerous thing’.

Have you got a link to the account, please? Maybe someone could then correct the author’s misunderstandings.
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Old 9th Jan 2021, 10:23
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B73 - if the twitter accounts owner tweets based on
the principle of ‘a little knowledge is a dangerous thing’.
you'll find his account has just been permanently suspended in the USA
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Old 9th Jan 2021, 11:59
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As an aside, I was involved (as a passenger) with professional helicopter firms for television for a few years a while back, and I only once witnessed the pilot climb up and have a really good look at the main rotor hub and all its ball joints and tie rods etc. before starting up. And on this one occasion, the CAA were in attendance !!
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Old 9th Jan 2021, 14:09
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Originally Posted by Uplinker View Post
As an aside, I was involved (as a passenger) with professional helicopter firms for television for a few years a while back, and I only once witnessed the pilot climb up and have a really good look at the main rotor hub and all its ball joints and tie rods etc. before starting up. And on this one occasion, the CAA were in attendance !!
That is just stupid
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Old 9th Jan 2021, 14:39
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Uplinker, I don’t know who you were flying with but checking the rotor head on any helicopter is an essential part of the daily check.
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Old 9th Jan 2021, 14:51
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Originally Posted by MeddlMoe View Post
The numbers per flight hour for helicopters are somewhere between commercial airlines and private small planes. If you go by traveled passenger miles there is a huge difference between commercial airlines and helicopters.
Not surprising, seeing that most accidents happen at the departure or approach-and-landing phases, but sector times and lengths, and passengers per aircraft, are far greater in commercial airliners than in helicopters. A one-hour sector in a 100-seat airliner at 300mph gets you 30,000 passenger-miles - a half-hour sector in a 4-seat helicopter at 100mph gets you 200 passenger-miles - but each aircraft does just one takeoff and one landing. Numbers per sector would be more useful.

waterways are dangerous places to land with a helicopter.
Surely less dangerous than the streets and houses of a city centre. As I understand it, the restriction of single-engine helicopters to waterways in major conurbations like London is not for the safety of the helicopter but for the safety of the people underneath.
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Old 9th Jan 2021, 16:38
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One of the obvious differences in failure modes between fixed and rotary wing is predicated on the fact that the lifting surfaces on a helicopter are spinning at around 400 rpm and are connected to the airframe via a very complex system of hinges, pivots, drive shafts, dampers, bearings and tie-bars. Not only is this engineering triumph spinning at 400 rpm, but it is (hopefully) finely balanced and tracked to provide a smooth ride. On a fixed wing, the lifting surfaces are fixed with bolts, fasteners, spars and welding and are an integral part of the airframe, attached in a far more sedate and civilized manner.

"So what" you ask?

Back to failure modes. You can do some serious damage to a wing assembly and still stay safely in the air. There are plenty of examples in history of losing quite important bits from a wing, and in the case of an Israeli F-15, almost the entire wing, only to land relatively safely and have a great story to tell in the bar. Not so with a helicopter. If you are unfortunate enough to either lose a piece of the spinny bits on top, or have something cause an major imbalance, the natural desire of the helicopter is to try and shake itself to pieces, shedding all the important bits along the way. It doesn't need to be the whole blade (which is instantly catastrophic), the loss of a tip cap, trim tab or chunk of filler will all cause your work/life balance to deteriorate rapidly.

Luckily these are rare events, but in terms of suffering damage to a rotating assembly, it will by its very nature lead to unstable and amplifying events. When things go wrong, they go wrong suddenly and violently.

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Old 9th Jan 2021, 18:03
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Originally Posted by Uplinker View Post
As an aside, I was involved (as a passenger) with professional helicopter firms for television for a few years a while back, and I only once witnessed the pilot climb up and have a really good look at the main rotor hub and all its ball joints and tie rods etc. before starting up. And on this one occasion, the CAA were in attendance !!
I don't know any more context but it depends if it's the first flight of the day or not. On some types there's no detailed inspection of the rotor head required between flights (turnaround/inter-flight checks), only before the first flight of the day (daily check).
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Old 9th Jan 2021, 18:21
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Years ago I did a statistical comparison between helicopters and other modes of transportation, the fatality rate is less than motorcycles operated on public roads.
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Old 9th Jan 2021, 21:56
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On a training flight, the most dangerous thing you will do is drive to the airport.
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Old 10th Jan 2021, 00:41
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Survived recurrent training today. First auto was a bit rough but serviceable. The remainder smooth. As always, very worthwhile. Perfect practice makes perfect. Sat in the back to watch a newbie's second hour of training. That was far more frightening But very educational to this budding CFI.
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Old 10th Jan 2021, 22:14
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Originally Posted by MLH View Post
Years ago I did a statistical comparison between helicopters and other modes of transportation, the fatality rate is less than motorcycles operated on public roads.
Which brings up an interesting point about comparison of auto and aircraft accident rates. It might make more sense to base comparison numbers on accidents/trip rather than per mile, as the median aircraft trip might be 500 miles and the median car trip might be 5 miles; the average driver might make 500 trips/year while the flyer might make 5/year......
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