Ed Helicopter Crashes into Glasgow Pub

[Skwinty]

One other point to consider. At 0 knots forward velocity and 1000' altitude, how does one expect to attain the recommended 75 knots forward velocity at 100'. This is not a vehicle rolling down a hill.

 

[BenBurch]

JohnLondon,

That's the point I was making. NO other thing occupied him.

He had an anomaly in front of him and he did not consider the actual solution because he had walled off the idea. I'm betting he tried all sorts of flight attitudes to get the fuel to flow.

-BenB

 

[LondonJohn]

The issue to consider is this. The helicopter is flying at 1000' AGL over a city and not an autorotation practice field. The pilot receives low fuel warnings and rightly or wrongly assumes 10 minutes flight time remaining. He calculates that he should make home base albeit with less fuel remaining than is legal. For whatever reasons, as yet undetermined, the engines stop running. The clock starts ticking and even if the pilot had successfully initiated autorotation the ground is at best 30 seconds away. That is not a lot of time to resolve the problem. After all, this was not a daytime autorotation training exercise over the airfield. Now I am not saying that autorotation cannot be successfully carried out at low altitude during a training session because the pilot is preparing and expecting to perform the manoeuvre. It's a different scenario when the need arises at night unexpectedly. In any event, altitude and forward velocity are crucial in ensuring a successful autorotation. There is no need to assume criminal or negligent intent on the part of the pilot.

It sounds like you might be misunderstanding the evidence quite significantly.

The "low fuel" alarms would have started to sound several minutes before the engines finally flamed out. That's what the alarms are designed to to. The AAIB found that the sensors and alarms were all working fine.

Therefore, the pilot had already had his "ten minutes" of flying time when the engines flamed out and stopped working. In fact, he had had ten (or so, perhaps more) minutes of serial warnings that were increasing in number and urgency.

So even if the pilot was winging it and hoping he could get back to base in time (which in itself would have been a grossly improper thing to do), he would have had to hideously miscalculate even this "winging it" approach - he was still several minutes' flying time from his base at the point when the engines eventually ran out of fuel and flamed out. In other words, at the time of the first alarms, the pilot must have (or ought reasonably to have) known that he had probably around 20 minutes' flying time to reach his base, and that even a "winging it" strategy was therefore doomed to failure. And when he had already flown for several minutes after the first alarms, and realised that he was still a long distance from his base, he should without doubt have realised that he had badly miscalculated his "winging it" strategy and that it was time to cut his losses and land immediately.


I also don't understand what you're now claiming about the autorotation landing situation. Are you now saying that the fact that it was not a "perfect" training scenario could have had a material impact on the pilot's ability to do the job? If so, then they need to change their training and certification programmes, since NO real-life engine failure is ever going to match "perfect" conditions.

Lastly, you seem to be picking up others' strawman points. I am NOT "assuming" the pilot's actions to have been criminal or wantonly negligent. What I AM saying is that in my opinion it's hard to explain the totality of the incident in "simple" terms. And that "totality" part is also very important to my argument. I have already stated that in my opinion the very last part of the incident is absolutely explainable in relation to "simple" human factors such as panic, freezing, incorrect inputs under stress, poor training, etc. I fully accept that any or all of these things might have caused the pilot to fail to react once the engined flamed out. But when you look at this part of the incident alongside everything that preceded it, that's when it gets difficult for me to explain the total incident. And once again, I only suggest that one possible explanation might be deliberate pilot action/inaction.

 

[LondonJohn]

JohnLondon,

That's the point I was making. NO other thing occupied him.

He had an anomaly in front of him and he did not consider the actual solution because he had walled off the idea. I'm betting he tried all sorts of flight attitudes to get the fuel to flow.

-BenB

Yes, perhaps so. But if he did try all sorts of approaches (including, as you say, attitude adjustments) to resolve the "low fuel" emergency, then why didn't he reach a point fairly quickly where he realised that a) none of his approaches was having the desired effect, and b) the low-fuel situation had now gone on for some minutes, and must therefore be approaching critical status (as a glance at his fuel gauge would have confirmed).

At that point, why wouldn't he have realised that he - for whatever reason - couldn't figure out how to solve the problem and taken the proper corrective action: land the aircraft safely? After all, even a potential blow to his pride and professional reputation is a small drop in the ocean compared with the ultimate damage - to his reputation, his aircraft, and himself (and others) - of risking letting his helicopter simply run out of available fuel.

 

[LondonJohn]

One other point to consider. At 0 knots forward velocity and 1000' altitude, how does one expect to attain the recommended 75 knots forward velocity at 100'. This is not a vehicle rolling down a hill.

Under these conditions, you have 900 feet of altitude to attain 75 knots of forward speed. No problem whatsoever.

And yes, in a very real sense this IS a vehicle rolling down a hill. In fact, it's even better than that, because you don't have rolling resistance or other solid-surface frictions to impair your growth of speed.

Have you ever ridden on a sizeable roller coaster? When you get to the very top of the chain-rise (on a "traditional" coaster), you're doing virtually zero forward speed. The coaster then topples over the edge of the first big drop. It quickly attains significant forward speed as it trades height for speed (it converts potential energy into kinetic energy). By the time the coaster reaches the bottom of the first big drop, it can be travelling very fast indeed.

And that's what is essentially happening in the first part of an autorotation manoeuvre. The pilot (simply put) points the aircraft downwards and converts height into forward speed. Then, 100 feet from the ground (in the case of this particular model) he flares the aircraft back upwards, having attained sufficient speed to cause sufficient autorotation in the blades to cushion the subsequent descent to ground.

With 900 feet to work with, there is no doubt whatsoever that it's possible for a pilot in a stationary aircraft to attain 75 knots of speed. And in any case, the helicopter in the Glasgow accident was (by every account) not hovering at the time when the engines flamed out, but was actually flying forwards at a reasonable speed (let's be extremely generous and suggest that it was flying at 30 kts, although in reality it's likely that it was actually doing more than 75 kts!). So even by the most pessimistic estimation, the aircraft already had 30 knots of forward speed to work with (and it's highly likely that in fact it already had the sufficient 75 knots of forward speed).

Whichever way you cut it, the pilot at the controls of that helicopter should without doubt have had much more than sufficient altitude and speed to carry out a successful and safe autorotation landing (leaving aside the issue of selecting where the aircraft would actually put down, which might have been a point of difficulty, but obviously not a reason in and of itself not to perform the autorotation manoeuvre). The only question is why the pilot apparently didn't even try to perform an autorotation. I am fully able to accept (as I've said before) that the pilot might have frozen, panicked, performed the wrong inputs in error, or even (at a huge stretch) have forgotten what to do in such a situation. But none of that detracts from the fact that it should have been entirely possible for a competent pilot to have performed a successful autorotation under these specific starting conditions.

 

[Skwinty]

Well in that case, I bow to your superior knowledge and experience in helicopter operations and accident investigations.

Please carry on.

 

[LondonJohn]

Well in that case, I bow to your superior knowledge and experience in helicopter operations and accident investigations.

Please carry on.

Do I detect....... a hint of sarcasm in that remark??

Seriously, if you think my analysis is faulty, I want to know about it. I know a reasonable amount about general aviation, and have what I would consider a scientific mind. But I am not particularly knowledgeable about helicopter aviation, and I'm not suggesting that my views on general aviation are infallible either.

What I am doing is calling it as I see it, based on what I believe is sound underlying reasoning. I think that I have a good argument - based on empirical evidence - to suggest that the helicopter in question, flying at that altitude and likely speed (but even if it was a zero speed), should easily have been able to have been piloted to a successful autorotation landing once the engines flamed out.

If you or anyone wants to challenge that opinion (or any other ofmy opinions), I am more than happy to have that happen. If anyone can tell me why I've either a) got the evidence wrong, or b) misinterpreted the evidence, or c) failed to apply fundamental logic or reasoning, then I am all too keen to see that. I am keen to learn as much as debate.

 

[Skwinty]

Yes, i was being a tad sarcastic. I should have used this emoticon.

From AAIB Bulletin S2/2014

The helicopter’s altitude as it approached the area of the accident was approximately 1,000 ft amsl and its average groundspeed was approximately 105 kt.

The majority of the recorded data have no form of time stamp. So, whilst the order of some of the snapshots can be determined, their relative timing is unknown.

Other systems use time references but ones that are not directly linked to UTC.
The Warning Unit has provided information on the order in which warnings were triggered during the flight but not when they occurred. The unit recorded the normal warnings associated with starting the helicopter, followed by a warning free status.

Preliminary analysis of the FADEC data indicates that the right engine flamed out, followed, a short time later, by the left engine also flaming out.
Since the maintenance reports only give timings relative to the moment the FADECs were turned on (which is not recorded), the exact times at which these flameouts occurred is unknown.

So I question your insistence on asserting time frames.

I stand by my interpretation of autorotation with forward velocity and without. The crucial aspect is altitude and forward velocity.

When autorotating from zero forward velocity your rate of descent is extremely high and this higher rate of descent is acceptable provided that at the right time (above the H/V Curve), you gain the airspeed necessary for a reasonable flare and/or touchdown.

The name "hovering autorotation" is really a misnomer, because the helicopter actually never enters autorotation. Instead, the inertia of the spinning rotor system is used to produce thrust.

Anyway no more from me for now as it is dark outside and the seeing is good so I am off for some astrophotography.

 

[DGM]

Yes, perhaps so. But if he did try all sorts of approaches (including, as you say, attitude adjustments) to resolve the "low fuel" emergency, then why didn't he reach a point fairly quickly where he realised that a) none of his approaches was having the desired effect, and b) the low-fuel situation had now gone on for some minutes, and must therefore be approaching critical status (as a glance at his fuel gauge would have confirmed).

At that point, why wouldn't he have realised that he - for whatever reason - couldn't figure out how to solve the problem and taken the proper corrective action: land the aircraft safely? After all, even a potential blow to his pride and professional reputation is a small drop in the ocean compared with the ultimate damage - to his reputation, his aircraft, and himself (and others) - of risking letting his helicopter simply run out of available fuel.

Just for reference:



It would not be totally clear that he was running out of fuel. The "main" section of the gauge is the largest and it would be still blue (at a safe level). The warning indicators are just above the fuel gauge. There is also an "off" button for that display.

Note how this pilot has to look at the switches at the end and how tight they are.

 

[BenBurch]

Yes, perhaps so. But if he did try all sorts of approaches (including, as you say, attitude adjustments) to resolve the "low fuel" emergency, then why didn't he reach a point fairly quickly where he realised that a) none of his approaches was having the desired effect, and b) the low-fuel situation had now gone on for some minutes, and must therefore be approaching critical status (as a glance at his fuel gauge would have confirmed).

At that point, why wouldn't he have realised that he - for whatever reason - couldn't figure out how to solve the problem and taken the proper corrective action: land the aircraft safely? After all, even a potential blow to his pride and professional reputation is a small drop in the ocean compared with the ultimate damage - to his reputation, his aircraft, and himself (and others) - of risking letting his helicopter simply run out of available fuel.

When a person is seeing events they are not comprehending, in this case because of a "certain knowledge" that the transfer pump switches were on, and the problem is severe enough, panic can set in that prevents reconsideration of first principles.

In this case, he sees he has fuel in the main tank but the fuel in the transfer tanks is going down. What causes that? Well, if your belief that the transfer pumps are on is not reconsidered, you would believe that the fuel inlet is sucking air, and you would try to find an attitude that works to get you some fuel.

 

[Skwinty]

From AAIB Bulletin S2/2014

"An alarm gong was also recorded followed by intermittent warnings relating to low rotor rpm.

The Central Panel Display System (CPDS) displays cautions and fuel status information to the pilot. It also records internal display system faults but no information relating to its indications. The displays did record flight duration and work is being carried out to link this duration, and the conditions required to start and stop this recorded duration, to the flight path of the helicopter. A fault relating to one of the display systems was recorded and further work is being undertaken to establish the meaning and possible causes of the fault"

Once rotor RPM has decayed beyond a certain point no amount of attempts at autorotation will ever succeed.

 

[Matthew Best]

We get audio warnings for all sorts of things at work all the time. Sometimes I come in and find that the volume has been turned down to the point that they're almost inaudible just because they are so annoying.

 

[Skwinty]

The crew were also equipped with night vision goggles so it is possible that they dimmed all the instrumentation intensities to prevent excessive glare when using the NVG's.

The instrumentation intensities would have to be turned up again when not using NVG's.

 

[Craig B]

We get audio warnings for all sorts of things at work all the time. Sometimes I come in and find that the volume has been turned down to the point that they're almost inaudible just because they are so annoying.

May I ask what sort of workplace? I hope not a nuclear power station.

 

[Matthew Best]

Just a TV transmission centre - nothing life or death about it at all, so perhaps not a good comparison, but my impression is that people are capable of getting quite blase about all sorts of things if they do them enough.

 

[Sunstealer]

I've also read elsewhere that the "prime" pumps are not usually left on for flight(only for starting). I wonder if he simply wasn't paying attention and turned on the wrong pumps.

Many people, including me, have wondered if the pilot switched on the prime pumps instead of the transfer pumps as part of the procedure for transitioning to normal flight (from the hover).

I have been trying to find out what cautions are displayed when the transfer pumps are off because this is a vital aspect with regard to safe operation of this helicopter. An amber warning is displayed on the Caution and Advisory Display (CAD) on the Central Panel Display System (CPDS).

I was also looking for what is displayed when the prime pumps are turned on during normal flight, because from researching this topic I was under the impression that an amber caution is displayed in both cases. Today the answer was posted on the pprune thread:

http://www.pprune.org/8332830-post2423.html*

*Note: The top picture is actually the video which you can click or go here http://s52.photobucket.com/user/sil...6-439B-A569-0383FB1AF128_zpsjslqbhva.mp4.html

I can't see how any pilot, having switched the prime pumps on instead of the transfer pumps, would not instantly be be aware of the mistake. Even if the pilot acknowledges the warning, he is still left with the amber warning on the CAD showing prime pumps on and transfer pumps off.**

** If the CAD is still functioning.

This would lead me to believe that the prime pumps were not inadvertently switched on instead of the transfer pumps earlier in the flight, but were switched on much later (possibly in response to a number of things).

 

[DGM]

Many people, including me, have wondered if the pilot switched on the prime pumps instead of the transfer pumps as part of the procedure for transitioning to normal flight (from the hover).

I have been trying to find out what cautions are displayed when the transfer pumps are off because this is a vital aspect with regard to safe operation of this helicopter. An amber warning is displayed on the Caution and Advisory Display (CAD) on the Central Panel Display System (CPDS).

I was also looking for what is displayed when the prime pumps are turned on during normal flight, because from researching this topic I was under the impression that an amber caution is displayed in both cases. Today the answer was posted on the pprune thread:

http://www.pprune.org/8332830-post2423.html*

*Note: The top picture is actually the video which you can click or go here http://s52.photobucket.com/user/sil...6-439B-A569-0383FB1AF128_zpsjslqbhva.mp4.html

I can't see how any pilot, having switched the prime pumps on instead of the transfer pumps, would not instantly be be aware of the mistake. Even if the pilot acknowledges the warning, he is still left with the amber warning on the CAD showing prime pumps on and transfer pumps off.**

** If the CAD is still functioning.

This would lead me to believe that the prime pumps were not inadvertently switched on instead of the transfer pumps earlier in the flight, but were switched on much later (possibly in response to a number of things).

Thanks, that's an interesting read.

I use MS flight sim quite a bit and it's interesting to note the exact same thing happens in the sim. The CAD display does a good job at getting your attention.

I'm not sure if the real helicopter does the same thing but one thing I did notice. You don't get an indicator that the xfer pumps are not on until you get down to a certain level of fuel (not sure the exact amount).

 

[Darth Rotor]

Yes, you may well be correct. But if that was what did happen, then how can one explain the dual facts that a) the alarms didn't stop, but rather they not only continued but actually increased in number and urgency, and b) the fuel tank levels - which the pilot could quite clearly see in front of his face - was unequivocally continuing to fall towards empty?

I am not sure what he was looking at, and am not sure why you are sure. Most pilots in that region are puzzled at why, with what is reported as the low fuel warning lights having been illuminated, he did not make more haste to put the aircraft on the ground ... but that ten minute thing from the flight manual may have figured into it.

I believe that the evidence shows that the pilot made no radio calls to ATC or anyone else from the moment of the first low-fuel alarms.

Aviate, navigate, communicate. If he was busy trouble shooting fuel system and then an engine flame out, not much time for calling ATC.

You're saying that you wouldn't even have attempted an autorotation landing?

No, I am not. I am saying that if I were behind the aircraft when the second engine flamed out, I might have cocked up the autorotation.

And you're suggesting that you wouldn't have instinctively made a short urgent radio transmission to say you were going down?

No idea what I might have done, were I caught out. See "aviate navigate communicate" above.

And anyhow, I still have to come back to this "surprised at the engines flaming out" element of your suggestion. The pilot knew he had a critical fuel supply problem. He obviously knew that if the engines ran out of fuel they would flame out and shut down. He knew that the low-fuel alarms were sounding and getting more urgent. He could see at a glance the exact amount of remaining fuel in the supply tanks (and the sensors and instruments were all in perfect working order and totally accurate). How on Earth could he have been completely taken by surprise when the two engines failed in quick succession?

I don't know if that is how it went down, so I won't bother responding to your series of assumptions.

IIRC the operating manual says when the low fuel alarm activates the pilot should land the helicopter within 10 minutes.

Exactly. That issue has been under much discussion by those who operate that model helicopter.

1,000 feet is absolutely not considered "low altitude" for the purposes of an autorotation manoeuvre.

AGL, daytime, I agree.
MSL, over urban terrain, night?
Depends on how ready you are, how good you are, what you can see and where you think you can land. Making a precautionary landing before the fuel runs out beats having to shoot an auto. That point too has been under much discussion among EC-135 pilots.

I remain pretty shocked at the single-minded selective interpretation of the limited data available to conclude that the pilot deliberately crashed the helicopter.

*Chortle*

 

[LondonJohn]

I am not sure what he was looking at, and am not sure why you are sure. Most pilots in that region are puzzled at why, with what is reported as the low fuel warning lights having been illuminated, he did not make more haste to put the aircraft on the ground ... but that ten minute thing from the flight manual may have figured into it.

What did you read that suggests that I am "sure"? I smell straw......

I wrote that the pilot must have been able to at least see the fuel gauge. Moreover, given that he must have known that the problem pertained to low fuel (or would you challenge that assumption?), what would you posit as the odds on whether he looked at the fuel gauge in front of his face at least once throughout the whole event? Again, I am not SURE that the pilot looked at his fuel gauges, but if he did not, I would absolutely question why he did not.

As I wrote about the "ten minute" thing, it appears that the pilot had - and used - this period, starting from when the alarms first sounded, and ending when the engines eventually ran out of fuel and flamed out. This thing definitely did not happen in quick succession (the AAIB reports that the warning system was working as designed, meaning that there would have been plenty of time between the first alarm and the fuel eventually running dry).

Aviate, navigate, communicate. If he was busy trouble shooting fuel system and then an engine flame out, not much time for calling ATC.

As I said, he must (per the evidence) have had plenty of time in between the first alarms and the eventual flameouts. If he tried and failed for even three or four minutes to remedy the low fuel problem - and he must have known, by definition, that he had failed, since the alarms were only getting worse - then he still would have had plenty of time to radio the base, and prepare to land safely. I do know and understand the mantra you keep quoting back at me, but feel free to mention it some more if you like. In this instance (in my opinion), the pilot would have had more than enough time to do all three comfortably and safely.

No, I am not. I am saying that if I were behind the aircraft when the second engine flamed out, I might have cocked up the autorotation.

Yes I agree. But also, there appears to be no evidence that the pilot even attempted an autorotation. The evidence - as I understand it - is that the helicopter dropped out of the sky in a level attitude, with the blades having lost pretty much all rotational direction.

No idea what I might have done, were I caught out. See "aviate navigate communicate" above.

Ah yeah, you did repeat it again! And the aim of this discussion is to try to figure out why what happened in Glasgow happened. It necessarily involves scenario analysis at this point. The purpose of this debate therefore ought to be to try to evaluate which scenarios are reasonably possible, and after that, to try to hypothesise which might be the most likely scenario - all based on the available evidence.

I don't know if that is how it went down, so I won't bother responding to your series of assumptions.

Hang on a moment! YOU were the one who suggested that that was "how it went down" in the first place! I was explicitly responding to your suggested course of events. It's a bit rich therefore to write what you've written above. But at least it tells me something that's not directly related to the subject under discussion.......

Exactly. That issue has been under much discussion by those who operate that model helicopter.


AGL, daytime, I agree.
MSL, over urban terrain, night?
Depends on how ready you are, how good you are, what you can see and where you think you can land. Making a precautionary landing before the fuel runs out beats having to shoot an auto. That point too has been under much discussion among EC-135 pilots.

Agree on all of these. But a) the pilot in this case should have been somewhat ready: he had already experienced several minutes of growing alarms telling him explicitly that his engines were about to run out of fuel; b) he didn't attempt a precautionary landing while he still had fuel, even though he had ample opportunity and time to have done so; c) the evidence suggests that he didn't even attempt an autorotation once the fuel did finally run out.

*Chortle*

I see. Again, it's more instructive than you might realise regarding ulterior motives, hidden agendas and interpersonal issues. Personally, I'd prefer to stick to an adult debate about the core issues here, with the aim being education and advancement through shared knowledge and opinions, but each to his own I guess.

 

[383LQ4SS]

As I wrote about the "ten minute" thing, it appears that the pilot had - and used - this period, starting from when the alarms first sounded, and ending when the engines eventually ran out of fuel and flamed out. This thing definitely did not happen in quick succession (the AAIB reports that the warning system was working as designed, meaning that there would have been plenty of time between the first alarm and the fuel eventually running dry)..

There is one additional thing here. The "ten minute thing" is in regards to only the supply tanks reaching a certain level. This "ten minute" thing does not account for fuel that may remain in the main tank that becomes unusable during particular flight envelopes (low speed and hover?) He had additional fuel that could have been usable had he been in forward flight. This greatly clouds the "ten minute thing". He may have pulled into a slow crawl where fuel became unusable in the main tank...so he secured the transfer pumps as per checklist. He may then ignore the warnings coming from the feed tanks because he in fact has more than 10 minutes since some fuel remained in the main tank....which would become usable after transitioning to forward flight. Its up to the pilot to manage this "grey area". Follow with loss of situational awareness or distractions and he may well be caught off gaurd with engine flame out. Caught off gaurd with engine flame out he may well have hit the prime pumps to suck any last drops out in an attempt to keep the engines lit so he could transition to fwd flight in a further attempt to make the unusable fuel usable again.

The above again is speculation. But I feel very strongly the clues and facts on hand point to mental mistakes being made in this precarious envelope of operating at the low end of the fuel reserves where entering into and out of certain flight parameters creates differing scenarios regarding SOP's with fuel management coupled with the tank/pump configuration. And these differing scenarios can obscure things like the "ten minute thingy".

I still see no evidence of an intentional act.