Police helicopter crashes onto Glasgow pub: final AAIB report
I think a police pilot, at night with busy tasking and limited endurance, has quite enough to do without fannying around with fuel transfer pumps.
Sounds an eminently sensible practice - was it SOP?
Why no autorotation?
There's a vast amount of comment about the fuel pumps and running out of fuel, but that's not ultimately what caused the crash.
The lack of a successful autorotation caused the crash. Had Dave auto'd safely down, we'd probably all be thinking that he was a 'good pair of hand for getting it down safely, but a bit of a ****** for running out of fuel'.
I find it extremely hard to imagine, that in the heightened sense of arousal after the first donk stopped, that he didn't do his damnedest to autorotate. Knowing his UK mil background and how engrained the reaction to low NR has to become, I'm very confident he was perfectly capable, albeit maybe out of practice for 'full downs'. We know from the report that the RRPM dropped below 97% and he managed to get it back once so he was clearly on his game, but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......
There's a vast amount of comment about the fuel pumps and running out of fuel, but that's not ultimately what caused the crash.
The lack of a successful autorotation caused the crash. Had Dave auto'd safely down, we'd probably all be thinking that he was a 'good pair of hand for getting it down safely, but a bit of a ****** for running out of fuel'.
I find it extremely hard to imagine, that in the heightened sense of arousal after the first donk stopped, that he didn't do his damnedest to autorotate. Knowing his UK mil background and how engrained the reaction to low NR has to become, I'm very confident he was perfectly capable, albeit maybe out of practice for 'full downs'. We know from the report that the RRPM dropped below 97% and he managed to get it back once so he was clearly on his game, but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......
Last edited by jellycopter; 30th Oct 2015 at 19:42. Reason: typo
jellycopter but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......
Thomas coupling This particular pilot hadn't done an EOL auto for possibly decades.
Ergonomics? He had plenty of hours to get familiar with all such 'Gotcha's'.
Too many opportunities for the pilot to intervene were not acted upon. Tired perhaps? or just been doing it for so many years that this one night he somehow just couldn't been bothered (oh look a light has come on... there's another one... whatever, I'm just so bored with this s**t).
I think that this incident, and the other recent 'mystery' accidents should prompt us at this stage to be thinking about an element of psychological review of the flightcrew in addition to the AAIB investigation. People go through a lot in life, at diifferent life stages, sometimes quite low for no obvious reaasons.
Flug
Too many opportunities for the pilot to intervene were not acted upon. Tired perhaps? or just been doing it for so many years that this one night he somehow just couldn't been bothered (oh look a light has come on... there's another one... whatever, I'm just so bored with this s**t).
I think that this incident, and the other recent 'mystery' accidents should prompt us at this stage to be thinking about an element of psychological review of the flightcrew in addition to the AAIB investigation. People go through a lot in life, at diifferent life stages, sometimes quite low for no obvious reaasons.
Flug
but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......
The other, far more likely is simply panic. Seeing nowhere to go, not visualising the river as a clear area and an automatic motor response to arrest the descent occurring by reflex in what looked like a hopeless situation.
It's what people do, I'm afraid.
Sid, I get what you are saying. On a completely dark instrument panel, when you're looking directly at a screen focusing pretty much on the CAD display, then...yeah, those indications are pretty hard to miss. But the aircraft was VFR, over a city that was fairly well-lit. So there was probably plenty of light in that cockpit at the time. Not only that, but the evidence kind of shows that Dave was *not* looking at his instrument panel.
*IF* we believe that the EC-135's fuel quantity measuring and display system were functioning properly (and no concrete evidence was brought forth to suggest they were not), then how could Dave have *not* noticed his Supply tanks draining to zero? (What did he think was causing the low-fuel gongs?) Answer: He wasn't looking at the panel; his attention was directed somewhere else.
He cancelled the low-fuel gong multiple times. It is inconceivable to me that during that time he would not have looked at the gauges at least once! How is that possible? How do you misinterpret that graphic fuel quantity depiction?
Maybe...and like I said it's just a guess...but maybe when he reached up and turned the Transfers back on he wasn't even looking inside the cockpit (thus he didn't see the indications of Supply/Prime pump activation). We surely don't have any other plausible explanation why such a good pilot would make such an awful mistake. Maybe that's what bothers me the most about this crash.
And about Dave's auto? Like all of us, my ego makes me want to sit here and think to myself and promise you that *I* surely would have done a better job in that situation. But I cannot guarantee that. Perhaps I would have done the same thing, basically sitting frozen on the controls for those eight brief seconds. I like to believe I'm Chuck Yeager/Aaron/Norris all rolled into one awesome human bean. Most of the time though I'm just Chuckles the Clown. I cut that Dave guy a lot of slack.
*IF* we believe that the EC-135's fuel quantity measuring and display system were functioning properly (and no concrete evidence was brought forth to suggest they were not), then how could Dave have *not* noticed his Supply tanks draining to zero? (What did he think was causing the low-fuel gongs?) Answer: He wasn't looking at the panel; his attention was directed somewhere else.
He cancelled the low-fuel gong multiple times. It is inconceivable to me that during that time he would not have looked at the gauges at least once! How is that possible? How do you misinterpret that graphic fuel quantity depiction?
Maybe...and like I said it's just a guess...but maybe when he reached up and turned the Transfers back on he wasn't even looking inside the cockpit (thus he didn't see the indications of Supply/Prime pump activation). We surely don't have any other plausible explanation why such a good pilot would make such an awful mistake. Maybe that's what bothers me the most about this crash.
And about Dave's auto? Like all of us, my ego makes me want to sit here and think to myself and promise you that *I* surely would have done a better job in that situation. But I cannot guarantee that. Perhaps I would have done the same thing, basically sitting frozen on the controls for those eight brief seconds. I like to believe I'm Chuck Yeager/Aaron/Norris all rolled into one awesome human bean. Most of the time though I'm just Chuckles the Clown. I cut that Dave guy a lot of slack.
Tightgit
And about Dave's auto? Like all of us, my ego makes me want to sit here and think to myself and promise you that *I* surely would have done a better job in that situation. But I cannot guarantee that. Perhaps I would have done the same thing, basically sitting frozen on the controls for those eight brief seconds. I like to believe I'm Chuck Yeager/Aaron/Norris all rolled into one awesome human bean. Most of the time though I'm just Chuckles the Clown. I cut that Dave guy a lot of slack.
There seems to be a surprising focus on the failure to make a successful auto following double engine failure. Perhaps this is due to the report which states that the reason for unsuccessful autorotation is unknown.
If I was putting someone through their paces in a simulator, would we fail one engine, and then while they were sorting out the first failure, give them a second failure at 600ft, low speed, at night, no landing light, over a city?? Of course not. You'd be setting them up to fail. It might be a demonstration of why not to get yourself into that position in the first place, but I can't imagine that many would turn that into a successful auto.
You're low level
The first engine fails
You delay for a couple of seconds with shock, then carry out immediate actions
You're scanning the instruments and switches trying to work out why you have this confusion
You secure the engine
Suddenly the second engine goes
Multiple lights illuminate
The outside lights go dark
The NR has already dropped below safe
You have no option but to bottom the lever
Dropping through 300ft trying to recover Nr
Knowing you are descending way too fast and you have no accurate height figure
You know you have to raise the lever or certain crash
The difference between a Flaring too high, successful auto or crashing to the ground, probably about 2-3 seconds either way. Good luck perfecting that when you're also trying to look for somewhere safe to put the aircraft down and also trying to understand what has gone wrong.
The fact is the aircraft was upright and level when it hit the roof, just a few seconds after the second engine failure. Looking at the wreckage, it almost looked survivable and it possibly nearly was. A few seconds later before instigating the final 'pull', and it might have just had enough energy to arrest the descent into a heavy but survivable landing. Little point in debating this final element which the report acknowledges was in exceptionally demanding conditions.
As to the FDR/CVR. Its absence made no difference to this accident, just our understanding subsequently. As warnings are recorded by the onboard systems, this has yielded useful information. Just a shame that there isn't a time stamp on those captions as that would be an easy fix and would have provided more useful info.
Ergonomics, switch positions and 'what if' scenarios are being debated in the report and on this forum and within them is quite likely the answer to what went wrong. It probably doesn't matter which one of them is correct, as EC135 pilots are identifying possible scenarios that all need to be eliminated to help prevent similar accidents happening again.
If I was putting someone through their paces in a simulator, would we fail one engine, and then while they were sorting out the first failure, give them a second failure at 600ft, low speed, at night, no landing light, over a city?? Of course not. You'd be setting them up to fail. It might be a demonstration of why not to get yourself into that position in the first place, but I can't imagine that many would turn that into a successful auto.
You're low level
The first engine fails
You delay for a couple of seconds with shock, then carry out immediate actions
You're scanning the instruments and switches trying to work out why you have this confusion
You secure the engine
Suddenly the second engine goes
Multiple lights illuminate
The outside lights go dark
The NR has already dropped below safe
You have no option but to bottom the lever
Dropping through 300ft trying to recover Nr
Knowing you are descending way too fast and you have no accurate height figure
You know you have to raise the lever or certain crash
The difference between a Flaring too high, successful auto or crashing to the ground, probably about 2-3 seconds either way. Good luck perfecting that when you're also trying to look for somewhere safe to put the aircraft down and also trying to understand what has gone wrong.
The fact is the aircraft was upright and level when it hit the roof, just a few seconds after the second engine failure. Looking at the wreckage, it almost looked survivable and it possibly nearly was. A few seconds later before instigating the final 'pull', and it might have just had enough energy to arrest the descent into a heavy but survivable landing. Little point in debating this final element which the report acknowledges was in exceptionally demanding conditions.
As to the FDR/CVR. Its absence made no difference to this accident, just our understanding subsequently. As warnings are recorded by the onboard systems, this has yielded useful information. Just a shame that there isn't a time stamp on those captions as that would be an easy fix and would have provided more useful info.
Ergonomics, switch positions and 'what if' scenarios are being debated in the report and on this forum and within them is quite likely the answer to what went wrong. It probably doesn't matter which one of them is correct, as EC135 pilots are identifying possible scenarios that all need to be eliminated to help prevent similar accidents happening again.
Special,
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It seems odd to me that with so many chopper pilots now singing from the same page re this accident, that the AAIB put the AR failure down to "unknown". Have accident reports really become so anodyne that that there is zero tolerance to even educated speculation and, if so, are they not losing sight of the their real raison d'être? (to prevent re-occurrence, not that anybody should need to be told that)
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I have read through all the posts and I can't find any mention of when it is necessary to turn the Prime Pumps on. There are a lot of comments about the Transfer Pumps being off, and that the pilot inadvertently turned the prime pumps on when he meant to turn the transfer pumps back on.
Basically, with the fuel starvation, the engines would have started to suck air, and you get FUEL PRESS caution on CAD. The actions for this is to turn the PRIME PUMP(s) ON. This would explain the position of the switches, if that is how they were before impact.
Of course, not knowing what the fuel display actually indicated to him on the CAD, we will never know.
Another point raised by a colleague; once your electrical power is only being powered by the battery (following a double engine/generator failure), you constantly get a red BAT DISCH warning and audible gong appearing.
This is the same audio gong and another red warning in close proximity to the ROTOR RPM warning, which he probably also would have had in auto.
So put yourself in a position of looking out, at night, in auto over a city and you keep getting a red warning visible out of the corner of your eye, and the gong telling you (you assume) that the Nr is high (106%) and rising, so you raise the lever to contain (because that is what you are trained to do!! - forgetting in the heat of the moment that NR is your friend and it doesn't matter(to a point) if it gets too high) - where as the audio gong is for the BAT DISCH, and you cannot hear the Intermittent Low tone for LOW NR.
And it's proven that in high workload, it is your hearing that goes first. But as has been said, without a CVR/FDR....
Basically, with the fuel starvation, the engines would have started to suck air, and you get FUEL PRESS caution on CAD. The actions for this is to turn the PRIME PUMP(s) ON. This would explain the position of the switches, if that is how they were before impact.
Of course, not knowing what the fuel display actually indicated to him on the CAD, we will never know.
Another point raised by a colleague; once your electrical power is only being powered by the battery (following a double engine/generator failure), you constantly get a red BAT DISCH warning and audible gong appearing.
This is the same audio gong and another red warning in close proximity to the ROTOR RPM warning, which he probably also would have had in auto.
So put yourself in a position of looking out, at night, in auto over a city and you keep getting a red warning visible out of the corner of your eye, and the gong telling you (you assume) that the Nr is high (106%) and rising, so you raise the lever to contain (because that is what you are trained to do!! - forgetting in the heat of the moment that NR is your friend and it doesn't matter(to a point) if it gets too high) - where as the audio gong is for the BAT DISCH, and you cannot hear the Intermittent Low tone for LOW NR.
And it's proven that in high workload, it is your hearing that goes first. But as has been said, without a CVR/FDR....
FH1100. A very thoughtful post.
Your comments describe precisely what bothers me about this accident : I'm struggling to figure out what on earth can have been going on in that cockpit and more importantly in the mind of an experienced and evidently, in normal circumstances, entirely competent pilot, over quite a period of time.
As much as anything because of that sneaky horrible feeling ; if it can happen to someone like him, what chance have I got?
Hyds Out ; your description of the likely final sequence makes sense and also makes for dreadful reading/visualisation.
The human factors aspects are what intrigue and puzzle me.
Your comments describe precisely what bothers me about this accident : I'm struggling to figure out what on earth can have been going on in that cockpit and more importantly in the mind of an experienced and evidently, in normal circumstances, entirely competent pilot, over quite a period of time.
As much as anything because of that sneaky horrible feeling ; if it can happen to someone like him, what chance have I got?
Hyds Out ; your description of the likely final sequence makes sense and also makes for dreadful reading/visualisation.
The human factors aspects are what intrigue and puzzle me.
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I have read through all the posts and I can't find any mention of when it is necessary to turn the Prime Pumps on.
Basically, with the fuel starvation, the engines would have started to suck air, and you get FUEL PRESS caution on CAD. The actions for this is to turn the PRIME PUMP(s) ON. This would explain the position of the switches, if that is how they were before impact.
Another point raised by a colleague; once your electrical power is only being powered by the battery (following a double engine/generator failure), you constantly get a red BAT DISCH warning and audible gong appearing.
This is the same audio gong and another red warning in close proximity to the ROTOR RPM warning, which he probably also would have had in auto.
This is the same audio gong and another red warning in close proximity to the ROTOR RPM warning, which he probably also would have had in auto.
The only Nr Warnings were for low Nr, which is a tone and not a gong.
The Batt Disch did not come on until the fourth Low Nr Warning was activated. (P.33)
Nr Low - <97% ---Steady light & intermittent low tone (800 Hz)
Nr High ->106% - Flashing light & warning gong
Nr High =>112% - Flashing light & continuous high tone (2400 Hz)
- forgetting in the heat of the moment that NR is your friend and it doesn't matter(to a point) if it gets too high) - where as the audio gong is for the BAT DISCH, and you cannot hear the Intermittent Low tone for LOW NR.
You can also hear the actually sound of the gearbox/Nr dropping Or rising itself.
Again, the Batt Disch did not come on until the fourth Low Nr Warning was activated. (P.33)
And it's proven that in high workload, it is your hearing that goes first. But as has been said, without a CVR/FDR....
Last edited by SilsoeSid; 31st Oct 2015 at 13:16. Reason: Reference to report page number for Warnings sequence.
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Hopefully the FAI will bring out any human factors issues that may have been present within the crew or unit as a whole, and ask any questions that the AAIB may not be able to.
Purveyor of Egg Liqueur to Lucifer
Special25, I know what you are saying about sims, scenarios, situations and setups, but you paint a very different picture than that of the real situation;
"If I was putting someone through their paces in a simulator, would we fail one engine, and then while they were sorting out the first failure, give them a second failure at 600ft, low speed, at night, no landing light, over a city?? Of course not. You'd be setting them up to fail. It might be a demonstration of why not to get yourself into that position in the first place, but I can't imagine that many would turn that into a successful auto."
However, the real version of events, from page 7, is;
Totally different situations.
"If I was putting someone through their paces in a simulator, would we fail one engine, and then while they were sorting out the first failure, give them a second failure at 600ft, low speed, at night, no landing light, over a city?? Of course not. You'd be setting them up to fail. It might be a demonstration of why not to get yourself into that position in the first place, but I can't imagine that many would turn that into a successful auto."
However, the real version of events, from page 7, is;
The helicopter tracked towards GCH at an altitude of about 1,000 ft amsl, with a ground speed of approximately 100 kt. Between 2221:35 hrs and 2221:45 hrs, when the helicopter was about 2.7 nm east of GCH, the right engine flamed out, leaving the pilot with one engine inoperative (OEI). Approximately 32 seconds later, about 1.8 nm east of GCH, the left engine flamed out.
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Yes the ENG FAIL would trump the FUEL PRESS, but you still get FUEL PRESS first, hopefully.
With regards the warning for ROTOR RPM, the report says
"The next recorded warning was rotor rpm signifying an Nr of less than 97%".
Yes, the visual warning was recorded, but without an FDR, how it is not known that all of the 4 ROTOR RPM warnings related to low Nr. It doesn't stipulate exactly.
That was why I was highlighting the similarities between the high Nr gong at 106% and the BAT DISCH gong. Without a timescale for these warnings, they could have all merged into one. That is what I meant by the sound of the gong from the Battery may have affected other audio warnings.
My point about Nr control; is that when you are trained and tested in the real aircraft, you aim to keep 100-103% Nr, to prevent damage to the head/MGB. This gets ingrained, so that when you have something for real, you don't automatically let the Nr rise, because pilots rarely/ever train full done autos in the real thing in a MET helicopter.
This has been proven is some military helicopter accidents where the pilot only flew to the practice single engine Tq figures, as opposed to the real limits (pull the lever up to your armpit) because that's what they always did in training.
But overall, despite all the bells and whistles sounding, and looking at the table 3 on page 33 of the report, there were a few audio warnings, any pilot under a high workload with no spare capacity gets tunnel vision. That was my point about a person's hearing being the first thing to go. (Gongs vs Low tone vs gearbox noises vs cockpit noise). But again, things like that cannot be proven in a case like this.
You can see the difference in the evidence availability between this incident and the Norfolk 139.
With regards the warning for ROTOR RPM, the report says
"The next recorded warning was rotor rpm signifying an Nr of less than 97%".
Yes, the visual warning was recorded, but without an FDR, how it is not known that all of the 4 ROTOR RPM warnings related to low Nr. It doesn't stipulate exactly.
That was why I was highlighting the similarities between the high Nr gong at 106% and the BAT DISCH gong. Without a timescale for these warnings, they could have all merged into one. That is what I meant by the sound of the gong from the Battery may have affected other audio warnings.
My point about Nr control; is that when you are trained and tested in the real aircraft, you aim to keep 100-103% Nr, to prevent damage to the head/MGB. This gets ingrained, so that when you have something for real, you don't automatically let the Nr rise, because pilots rarely/ever train full done autos in the real thing in a MET helicopter.
This has been proven is some military helicopter accidents where the pilot only flew to the practice single engine Tq figures, as opposed to the real limits (pull the lever up to your armpit) because that's what they always did in training.
But overall, despite all the bells and whistles sounding, and looking at the table 3 on page 33 of the report, there were a few audio warnings, any pilot under a high workload with no spare capacity gets tunnel vision. That was my point about a person's hearing being the first thing to go. (Gongs vs Low tone vs gearbox noises vs cockpit noise). But again, things like that cannot be proven in a case like this.
You can see the difference in the evidence availability between this incident and the Norfolk 139.
Below the Glidepath - not correcting
Have accident reports really become so anodyne that that there is zero tolerance to even educated speculation and, if so, are they not losing sight of the their real raison d'être? (to prevent re-occurrence, not that anybody should need to be told that)
Flug, I think it was `Ergonomics` that killed the crew and others in this accident, and specifically `role` related,ie single pilot,night,V/IFR,police,SAR. Different from day V/IFR,VIP/pax.
As an ex-mil TP when assessing a particular cockpit for a particular `role`especially at night,one would spend hours working through scenarios/emergencies to determine the ideal postion of switches/lights/controls,and their shape /colour/feel/importance/relevance.
In the end ,one reached a compromise/best guess,as the manufacturer had already decided,unless one could change due to essential safety of flight considerations,supported by `higher authority`.
So,the first `gotcha` is the position of the fuel pump switches on the roof panel,not in line of sight,similar to other switches,not `beta lit`,and should be operated On/Off as required at low fuel states/low-speeds/attitude changes.Unsatisfactory,but people `worked around` the situation.
Not a problem for your VIP pilot,A-B,lightweight headset,no NVG, quick look-up,turn on switch,easy....
Second `gotcha` is the `Shed -Bus `switch,positioned at the rear /top of the panel....Not too difficult/dramatic if it` day VFR,but at night/IFR,if both genes.fail....and then a transmission/t-rotor,or double engine fail,do you have enough hands to get the lever down and fly the aircraft....?
Has there been any move to have a `shed-bus `switch in parallel ,mounted on the cyclic/collective,so that it is not necessary to go grovelling around the roof at this critical moment when you need lights and the rad.alt,as per the EASA requirements.....???? If not, why not...?
What happens when one has a double gene. failure? does the AFCS/A/P drop out; is the collective held by a `friction `knob or an electro clutch..can they be manually over-ridden..?do the hydraulics have accumulators for the control jacks..?
Why is the `Bat Disch` warning a `red` and a gong..surely it is only cautionary...
As an ex-mil TP when assessing a particular cockpit for a particular `role`especially at night,one would spend hours working through scenarios/emergencies to determine the ideal postion of switches/lights/controls,and their shape /colour/feel/importance/relevance.
In the end ,one reached a compromise/best guess,as the manufacturer had already decided,unless one could change due to essential safety of flight considerations,supported by `higher authority`.
So,the first `gotcha` is the position of the fuel pump switches on the roof panel,not in line of sight,similar to other switches,not `beta lit`,and should be operated On/Off as required at low fuel states/low-speeds/attitude changes.Unsatisfactory,but people `worked around` the situation.
Not a problem for your VIP pilot,A-B,lightweight headset,no NVG, quick look-up,turn on switch,easy....
Second `gotcha` is the `Shed -Bus `switch,positioned at the rear /top of the panel....Not too difficult/dramatic if it` day VFR,but at night/IFR,if both genes.fail....and then a transmission/t-rotor,or double engine fail,do you have enough hands to get the lever down and fly the aircraft....?
Has there been any move to have a `shed-bus `switch in parallel ,mounted on the cyclic/collective,so that it is not necessary to go grovelling around the roof at this critical moment when you need lights and the rad.alt,as per the EASA requirements.....???? If not, why not...?
What happens when one has a double gene. failure? does the AFCS/A/P drop out; is the collective held by a `friction `knob or an electro clutch..can they be manually over-ridden..?do the hydraulics have accumulators for the control jacks..?
Why is the `Bat Disch` warning a `red` and a gong..surely it is only cautionary...