This crash happened right by the shore near the U.S.S. Arizona Memorial in Hawaii. Everyone survived, although sadly a 16 year kid is in critical condition. Hope he pulls through...

http://gma.yahoo.com/helicopter-cras...23129247--abc-news-topstories.html

Article quote:

"A civilian helicopter crashed Thursday near the USS Arizona Memorial in Pearl Harbor, the U.S. Coast Guard said.

Five people were on board the single-engine helicopter, the Coast Guard said, including a 16-year-old boy, who was in critical condition following the crash, according to the Honolulu Emergency Services Department."

Did he hit a massive downdraft or did he just lose lift from slow rotor speed?

Quoting 32andBelow (Reply 1):

Looked like he auto rotated after engine fail to slow down the decent a little.

Quoting 32andBelow (Reply 1):

There was definitely a mechanical failure. I've read comments speculating a sprag clutch failure. You can hear the engine spooling up, so it was working.

It was really lucky that the rotor blades didn't hit land when it tipped over. With the amount of people at the Arizona Memorial Visitor Center, there could have been a lot more injuries.

Helicopter crashes are always scary for this design of helicopters. The small fuselage and engine on top mean they roll upside down very quickly after landing in water. One of the reasons everyone who pilots or works in these aircraft should undergo ditching escape training.

Quoting ha763 (Reply 3): There was definitely a mechanical failure. I've read comments speculating a sprag clutch failure. You can hear the engine spooling up, so it was working.

Definitely sounds/looks like that. I'm not a pilot, nor even very well versed with helicopters, but it seems to me like something connecting the main rotor to the engine gave way, which is why the engine revved up – it was freed of load. And that would of course explain the abrupt loss of lift and no autorotation (not sure if autorotation would have even helped at this stage tbh).

My only uncertainty is the yaw, which appears to be less hardcore than if all the engine power was being dumped into the tail rotor. But then again, helicopters aren't really my thing, so maybe it's normal and just doesn't look as severe as one might expect.

Regardless, touch situation, hope the injured parties recover swiftly and without issues.

A

He lost lift suddenly. An engine failure at that altitude should not have produced such a sudden drop. Somehow he negated his own lift.

Quoting angad84 (Reply 5): My only uncertainty is the yaw, which appears to be less hardcore than if all the engine power was being dumped into the tail rotor. But then again, helicopters aren't really my thing, so maybe it's normal and just doesn't look as severe as one might expect.

Engine power goes first to the main transmission through the clutch. From the main transmission it goes to the main rotor and the tail rotor. If the clutch failed, there is no engine power to main or tail rotor, so the amount of yaw seen in the video is normal.

I'm not a helicopter pilot but I know a few basic things about them. From looking at the video, I almost wonder if the pilot got into Vortex Ring State.

https://en.wikipedia.org/wiki/Vortex_ring_state

I seem to recall that in helicopters that there is a certain "danger zone" of combination forward airspeed and vertical descent rate that would send the craft into VRS. When this happens, the rotor essentially gets caught up in it's own tip vortex and loses most of its lift. Again, not saying this is the cause, just a curiosity when I saw the video.

[Edited 2016-02-19 07:26:45]

Video is not available in my region...

Makes you wonder. Was the low altitude during this crash a blessing or curse?
(could it have recovered somehow if this occurred at a higher altitude? Or was it a catastrophic failure of something and the low proximity to the ground saved lives?)

A number of observations.

- First - I wish all the commentators would shut up so I could hear it better.

- One commentator says "the tail rotor was clearly not running" - Likely WRONG. When you try to film a rapidly rotating object, unless you have a very high speed camera, your camera will not capture the image often enough to show actual rotation. What you see is the result of the frame rate (sample rate) interacting with the rotation (frequency). If the sample rate is too low - it cannot capture the frequency. This is called aliasing (Look up Nyquist Rate). In short - you cannot tell from this video what the tail rotor is doing. Note - it is unlikely even an expert looking frame by frame can be sure. When a signal (video) suffers from aliasing, the information is lost. Maybe, if you know the frame rate of the camera AND the speed of the tail rotor you could make a prediction. But if you do not know one - you are lost.

- Engine/transmission/drivetrain noise
This is a turbine powered ship - so the engine noise is the high frequency "whine"
In addition - I hear a much lower frequency sound that many are thinking is the sound of an engine. If there were a piston engine in the aircraft - that would make sense, but there is not.
That sound is not normal for a 206. Does not sound like the beat of the tail rotor - which is the only thing that could be close.
In short - there is nothing normal on a 206 that would make that sound. To me it sounds like a broken component in the drive train rotating. It is kind of a grinding sound to me.

- You can clearly hear the turnbine and the "grinding" noise increasing in frequency - that means speeding up. It might make sense in an older piston powered helicopter to hear the engine speed up/down in flight, but in a turbine - no. The RPM of the turbine is relatively stable.
- This sounds like a turbine running away because the load was removed. Consistent with a drive train failure.

Vortex ring state.
This does not look like a Vortex ring state to me. VRS happens when at high power, low speed, typically with a tail wind. I don't see any evidence of any significant wind and the ship is probably not that heavy.
Is that conclusive? No. But it does not look right to me.

In addition - to get out of a VRS - you turn to move out of the vortex. Trying to power out will likely fail as that increased the vortex. Also - you would not hear the turbine speed up as a result of higher power demand like you would in a piston engine powered ship. In fact, if you demand too much power - it is likely the turnbine would wind down, not up.

Ultimately - and this is based purely on listening to that video and not a conclusion - this sounds like a drive train failure that disconnected the rotor/gearbox (including tail rotor) from the engine suddenly (engine and grinding sound increasing in frequency).
The response to this is to autorotate - but autorotation from here would be challenging. In addition - remember - even a successful auto rotation would cause the helicopter to hit pretty hard
- it may be that what we see is a (partly?) successful auto rotation into water.
- it may also be the pilot did not successfully manage energy in an auto rotation.
- it may be also that whatever failed in the drivetrain cause the rotor to decay making auto rotation impossible.

Frankly - he did a pretty good job putting that ship down level and a straight. Had it been on land - not sure it would have been better.

Glad to see the bystanders jump in and help.

Best wishes for the passengers and pilot.

-bob

Is it possible he knew there was an issue and wanted to put it down on land or as close to land as he could before it broke? On Google earth I don't see any pads in this area that would give him any reason to be coming in like that, only thought is he knew he had to put it down close to shore. Good for him if that's the case. Hoping the critical boy pulls through.

Echoing Classa64, from all appearances he tried (and succeeded) in putting it down where the closest people that could assist were ... ie: he saw the people around the memorial and tried to get there best he could.

Kudos must go out to those on shore, too, who jumped in and assisted. Most certainly without that, that 16-year-old would be in a morgue today, instead of the ICU, and others on the helicopter would be there as well.

[Edited 2016-02-19 11:34:28]

Is the helicopter still in one piece?

Quoting rcair1 (Reply 11): Vortex ring state. This does not look like a Vortex ring state to me. VRS happens when at high power, low speed, typically with a tail wind. I don't see any evidence of any significant wind and the ship is probably not that heavy. Is that conclusive? No. But it does not look right to me.

The winds on Oahu were quite strong yesterday, but they would have been coming at the helicopter from the nose/right side....definitely NOT a tailwind. Obviously, there could have been no wind at the moment of the accident...I would describe it as a "gusty" day.

-Aloha!

The helicopter looks to be a piston-powered Enstrom...

I'm really surprised that whoever was operating it didn't have automatic water-inflatable pontoons on the skids (which I know for a fact are an option on the Robinson helicopters) on the bird. That might have kept the bird upright and floating on the water here, and saved the poor kid from his severe injuries...   

[Edited 2016-02-19 13:44:20]

Quoting rcair1 (Reply 11): Note - it is unlikely even an expert looking frame by frame can be sure. When a signal (video) suffers from aliasing, the information is lost.

Are you speaking as such an expert? Have you considered:

Common undersampling techniques to beat the Nyquist rate. Super-Nyquist?

Unless things are *perfect* integers (rare in the real world) there may be techniques to recover info particularly when the signal is not noisy (a blade is generally regularly spaced)

Even in the absence of these methods to address aliasing a camera has a shutter speed which can lead to motion blur which can drive various estimates from single frames dependent on resolution etc. Those estimates extended over time can drive slow down and speed up estimates. This is particularly useful if the shutter speeds are known or other knowing timing indicators are in the frame.

Even without that method the way image readouts often work (scanned in a pattern) the timing there can become another source of timing information - even with aliasing if you know the scanout rate on a chip that may let you get back to the velocity (think of the Jello effect of older cameras) of an object.

etc...

I'm guessing this will be carefully researched and the helicopter itself looks pretty recoverable.

The ditch training - ugh... very sad about the kid.

Quoting dynamo12 (Reply 17): Are you speaking as such an expert? Have you considered:

Yes, I've got a Ph.D. in EE with 30+ years of digital imaging experience and have built the cameras in phones like this - including patents in over-sampling (often called super resolution).
That said - I will compromise with you in that you could make estimates or educated guesses if you really dug into it and knew the specifics of the sensor system and typical speeds rotor/tail rotor.

Since pilot and ship are available, it is more likely direct physical evidence is more useful.

Quoting KELPkid (Reply 16): The helicopter looks to be a piston-powered Enstrom...

I don't think so. 2 blade rotor - I think most Enstrom's have 3.
And

"U.S. Navy spokeswoman Agnes Tauyan identified the aircraft involved in Thursday's crash as a Bell 206. The names of the five people on board were not immediately released."

Quoting rcair1 (Reply 18): Yes, I've got a Ph.D. in EE with 30+ years of digital imaging experience and have built the cameras in phones like this - including patents in over-sampling (often called super resolution). That said - I will compromise with you in that you could make estimates or educated guesses if you really dug into it and knew the specifics of the sensor system and typical speeds rotor/tail rotor.

BURN!!

Quoting rcair1 (Reply 11): - First - I wish all the commentators would shut up so I could hear it better.

Quoting axelesgg (Reply 9): Video is not available in my region...

Here. Full, unedited video by the original uploader: http://www.youtube.com/watch?v=0sTTGlqZDx0

Not sure if the video is available worldwide, but here's a recording of the ATC transmission.

http://www.hawaiinewsnow.com/clip/12...fore-pearl-harbor-helicopter-crash

Can't be sure - but from that last video (Post 21), it looks as if the rotor blades may suddenly have gone from horizontal to about 45 degrees up?

Can someone who knows more about helicopters please comment?

[Edited 2016-02-20 01:12:37]

Quoting axelesgg (Reply 9): Video is not available in my region...

Apologies axelesigg. Thanks to N415XJ for the supplement. ha763 as well .

Quoting rcair1 (Reply 11):

And rcair1, last but definitely not least, thanks for shedding some light.

The teen boy who was trapped underwater in the helicopter has passed away.

http://khon2.com/2016/02/22/teen-in-...-arizona-memorial-pronounced-dead/

I was really hoping the boy would have survived, R.I.P

Sad end to what should have been a great vacation..

Quoting ha763 (Reply 26):

Quoting Classa64 (Reply 27):

R.I.P.

So sad he past away, how wonderful that the parents donated organs in his memory.   

Quoting rcair1 (Reply 11): I hear a much lower frequency sound that many are thinking is the sound of an engine. If there were a piston engine in the aircraft - that would make sense, but there is not. That sound is not normal for a 206. Does not sound like the beat of the tail rotor - which is the only thing that could be close. In short - there is nothing normal on a 206 that would make that sound. To me it sounds like a broken component in the drive train rotating. It is kind of a grinding sound to me.

The lower frequency noise sounds a lot like a tail rotor overspeeding. Last time I heard that was nearly 50 years ago after a transmission failure and the big propeller on top departed the aircraft. Heard the tailrotor overspeed, followed by a loud "thump".

Quoting ha763 (Reply 26): http://khon2.com/2016/02/22/teen-in-...-arizona-memorial-pronounced-dead/

This news report was a sucker punch to the gut, especially given my work as a pediatrician.

Too young. Way too young.

Quoting readytotaxi (Reply 29): how wonderful that the parents donated organs in his memory.

Always such a tough call. But the right call. He's gone, but his heart is still beating.

Preliminary report of the accident:

http://www.ntsb.gov/_layouts/ntsb.av...ef.aspx?ev_id=20160218X71040&key=1

Quote: The pilot reported to the National Transportation Safety Board (NTSB) investigator-in-charge, that while in cruise flight over Ford Island, he felt a vibration followed by a grinding noise. Shortly after, the pilot heard a loud bang, scanned the instrument panel and saw that the engine instruments indicated the engine was still running, however, rotor rpm decreasing. The pilot initiated an auto rotation to a grassy area near Contemplation Circle at the World War II Valor in the Pacific National Monument. As the pilot neared his intended landing area, he observed multiple people within the area. The pilot stated he initiated a left pedal turn, attempting to land close to the shoreline. Subsequently, the helicopter descended rapidly into the water, about 20 feet from the shoreline.

It looks like the pilot did a heck of a job! Tragic the 16 year old didn't survive.  

Sad the instinct of the people on the ground was to take the video rather than run like hell. The person who took the video and others near by cost the boy his life...

Quoting ikramerica (Reply 34):

Are you serious? On second thought, don't bother answering. I wouldn't want to hear what you'd have to say....

Quoting cyeg66 (Reply 35):

Did you read the pilot statement? Obviously you didn't. Too busy being indignant. Or is that ignorant?

He was going to put the copter down on land but the people on the shore didn't move so he had to ditch in the water. Who do you think those people were? The ones taking the video and those around them.

The kid was trapped in the sinking copter and died. Had it landed instead...

Whatever happened to the instinct to run from danger rather than filming it?

The helicopter went down like a tonne of bricks.

Nobody could have saved it. As much as we all wish we could.

Quoting ikramerica (Reply 34): Sad the instinct of the people on the ground was to take the video rather than run like hell. The person who took the video and others near by cost the boy his life...

No one cost this poor kid his life, its a sad accident. The people on the ground have no idea why he was coming in so close, I would have thought he was doing a flyover if I was there. The way I read the report was he saw people in the area and put it down close to shore preventing more injuries....And about the person filming...

Quote from article...
http://www.cbc.ca/news/world/hawaii-...-harbor-helicopter-crash-1.3456202

"He stopped filming and jumped in the water to help.

U.S. Navy spokeswoman Agnes Tauyan said the helicopter sank shortly after going down near the visitor centre Thursday.
'I took off my shirt and dove in'

Another bystander who jumped in to help was tour guide Chris Gardner, who was with a group at the Pearl Harbor Visitor Centre when he heard the crash.

"I took off my shirt and dove in," he said, describing how he, a navy sailor, a federal police officer and another man took turns diving to the submerged helicopter and trying to free a passenger with a knife. "He was strapped into his seat in the back of the aircraft."

Quoting coolian2 (Reply 37): The helicopter went down like a tonne of bricks. Nobody could have saved it. As much as we all wish we could.

It might not have been what the pilot actually intended but it actually looked to me like the he deliberately belly-flopped the chopper into the water (but very close to the shoreline) to absorb the impact. Imagine hitting land at that speed. Plus the rotors were still turning. I can't imagine what damage and possible carnage flying pieces might have done.

It is tragic that the boy died. But it could have been worse... whether there were people nearby filming or running away as fast as they could.

I am 100% confident in a fixed-wing aircraft. But whirly-gigs, not so much. A friend from high school died in a helicopter crash that fell a whole four feet to the ground.

Quoting ikramerica (Reply 34): Sad the instinct of the people on the ground was to take the video rather than run like hell. The person who took the video and others near by cost the boy his life...

Pretty strong statement. Just because the pilot intended to land on dry land does not mean the aircraft is capable of complying. Since the only video I saw starts with the helicopter over the water with very little airspeed and an increasing sink rate, it's pretty difficult to know if he had the altitude and airspeed to accomplish a successful autorotation to the land.

Quoting copter808 (Reply 40): Pretty strong statement. Just because the pilot intended to land on dry land does not mean the aircraft is capable of complying. Since the only video I saw starts with the helicopter over the water with very little airspeed and an increasing sink rate, it's pretty difficult to know if he had the altitude and airspeed to accomplish a successful autorotation to the land.

The preliminary reports from the NTSB shared above suggests the pilot deliberately adjusted his flight path after observing multiple people in the area he was planning to put down:

Quoting ha763 (Reply 32): Preliminary report of the accident: http://www.ntsb.gov/_layouts/ntsb.av...spx?ev_id=20160218X71040&key=1 Quote: The pilot reported to the National Transportation Safety Board (NTSB) investigator-in-charge, that while in cruise flight over Ford Island, he felt a vibration followed by a grinding noise. Shortly after, the pilot heard a loud bang, scanned the instrument panel and saw that the engine instruments indicated the engine was still running, however, rotor rpm decreasing. The pilot initiated an auto rotation to a grassy area near Contemplation Circle at the World War II Valor in the Pacific National Monument. As the pilot neared his intended landing area, he observed multiple people within the area. The pilot stated he initiated a left pedal turn, attempting to land close to the shoreline. Subsequently, the helicopter descended rapidly into the water, about 20 feet from the shoreline.

It is worth pointing out the report doesn't tell us how many people were in the area, whether they were already there or moved in during the accident sequence, and whether they could reasonably have been expected to realise they were impeding the landing and be able to move out of the way. No doubt those questions will be answered in the final report, but until then I think it may be premature to lay blame on people on the ground.

V/F

Yes, I'm being both indignant, AND ignorant..,  

I think maybe, just maybe, you'll start to realize how asinine your accusation toward perfectly regular folk, enjoying a perfectly regular day, visiting a very famous war memorial had no f+#^}g idea what was transpiring. These aren't slimy TMZ "reporters", but everyday citizens minding their own business when a chopper falls out of the sky mere meters from them on an otherwise uneventful day. To be honest, I'm of the opinion that video documentation is (can be) important in events like these to help investigators figure out how events unfolded. But to point the finger at them because they happened to "be" in the way, is quite illogical. Again, just my opinion, obviously very different to yours, and far less emotional, apparently. Hope you have a nice day, because I'm sure none of the people involved are having one, survivor's guilt onset, yada yada....