Police helicopter crashes onto Glasgow pub
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The one aspect that cannot be aligned with TC's scenario (post 482) is that both a member of the band, and a member of the audience have stated that to the occupants of the bar, it was a two-stage process - initially part of the ceiling fell in, specifically causing someone to joke that "the band had brought the house down", followed a few moments later the full destructive collapse. In the scenario described in the previous post there is only the single, massively destructive, impact. What else might have caused the initial, more minor ceiling damage in the above scenario? Not something falling form the helicopter as the AAIB have said nothing fell off (and anyway, if the aircraft had been in free-fall, nothing could have fallen much faster to get down to ground level several seconds ahead of the helicopter itself), and nor could it have been just downwash if the rotors were not generating significant lift.
All I can think of - and I cannot say it is entirely convincing but it is the best I can do - is a scenario of a more-or-less under control autorotation (as stated elsewhere, strobe effects of either the aircraft's own lights, or perhaps dischage street lighting providing an *illusion* of a stationary rotor), but the pilot realising at the very last moment that he was not above a ground-level car-park, but rather over a roof perhaps 12 feet higher, leading to a rapid and aggressive final lifting of the lever to check the descent, in poor light with limited cues, which actually over-checked the descent and briefly got the aircraft rising before the rotor energy ran out, leaving the aircraft to then fall from perhaps 10 feet through the roof. In that scenario there would be a sharp pulse of downwash that could perhaps have caused the initial limited ceiling damage, and a few seconds between the downwash pulse and the impact.
(Previously I was among those favouring a "progressive roof collapse" as providing the time period between first roof contact and total roof failure, but I have to admit to the difficulty of aligning that scenario with the degree of damage to the nose and skid areas.)
(Edited to include post number for TC's recent input)
All I can think of - and I cannot say it is entirely convincing but it is the best I can do - is a scenario of a more-or-less under control autorotation (as stated elsewhere, strobe effects of either the aircraft's own lights, or perhaps dischage street lighting providing an *illusion* of a stationary rotor), but the pilot realising at the very last moment that he was not above a ground-level car-park, but rather over a roof perhaps 12 feet higher, leading to a rapid and aggressive final lifting of the lever to check the descent, in poor light with limited cues, which actually over-checked the descent and briefly got the aircraft rising before the rotor energy ran out, leaving the aircraft to then fall from perhaps 10 feet through the roof. In that scenario there would be a sharp pulse of downwash that could perhaps have caused the initial limited ceiling damage, and a few seconds between the downwash pulse and the impact.
(Previously I was among those favouring a "progressive roof collapse" as providing the time period between first roof contact and total roof failure, but I have to admit to the difficulty of aligning that scenario with the degree of damage to the nose and skid areas.)
(Edited to include post number for TC's recent input)
Cabby:
Not often, as most jobs are about 30-40 minutes, but very occasionally.
Not once in 17 years of Police flying have I had a bobby try and persuade me to stay pass the point where I've said, "Time to go guys".
Fuel limits are often flown to minima's on police ops.
Its usually the police who want to stay on task longer
@nomorehelosforme: I would guess no, or very little control. From what I see now, I would guess the term Heavy landing is correct. I'd say crash.
If in control I believe no one puts it down with lot of nose down attitude.
Nose down attitude, damages and signs of no/very low rotor rpm does'nt point towards a deliberate choise to land where it came down.
About the roof/ceiling and the separate events of bang and ceiling coming down: Could it be possible that the impact destroyed /cracked the concrete roof, but it did hold together for a short while by reinforcement ? Thinking about how reinforced concrete hold together, when you break the concrete and the weight of the concrete makes the roof come down a small bit, the tension in the reinforcement increases until it snaps ?
If in control I believe no one puts it down with lot of nose down attitude.
Nose down attitude, damages and signs of no/very low rotor rpm does'nt point towards a deliberate choise to land where it came down.
About the roof/ceiling and the separate events of bang and ceiling coming down: Could it be possible that the impact destroyed /cracked the concrete roof, but it did hold together for a short while by reinforcement ? Thinking about how reinforced concrete hold together, when you break the concrete and the weight of the concrete makes the roof come down a small bit, the tension in the reinforcement increases until it snaps ?
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Could it be possible that the impact destroyed /cracked the concrete roof,
Concrete might have been the material between the ceiling and the original first floor floor, but I doubt it.
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On the subject of data recording - it is available, it is (relatively cheap) and light.
Okay, not attached to a twin turbine helicopter but on our piston engine FW kitplane we have a Dyonon SkyView system which after a recent software upgrade records 30+ data inputs direct onto a USB stick. Data includes flight and engine information on a continuous download and a 15 minute loop.
A complete 10" glass display EFIS, engine display and map for £5k. How do they do it? Simply that it isn't certified.
If the manufacturers and regulators made life more simple then every aircraft no matter what could be fitted with FDRs.
Okay, not attached to a twin turbine helicopter but on our piston engine FW kitplane we have a Dyonon SkyView system which after a recent software upgrade records 30+ data inputs direct onto a USB stick. Data includes flight and engine information on a continuous download and a 15 minute loop.
A complete 10" glass display EFIS, engine display and map for £5k. How do they do it? Simply that it isn't certified.
If the manufacturers and regulators made life more simple then every aircraft no matter what could be fitted with FDRs.
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About the roof/ceiling and the separate events of bang and ceiling coming down: Could it be possible that the impact destroyed /cracked the concrete roof, but it did hold together for a short while by reinforcement ? Thinking about how reinforced concrete hold together, when you break the concrete and the weight of the concrete makes the roof come down a small bit, the tension in the reinforcement increases until it snaps ?
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Tc
I would suggest something different...
Tail rotor failure. Resulting in the aircraft spinning violently out of control so pilot shut both engines down.
Therefore explaining why no rotation marks on impact.
2 Tail rotor failure - non starter - no rotational witness marks on impact.
Tail rotor failure. Resulting in the aircraft spinning violently out of control so pilot shut both engines down.
Therefore explaining why no rotation marks on impact.
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Stu B (and all)
I said more or less the same a bunch of pages back.
One thing nobody but me seems to have commented on is the (relatively) small hole in the roof about 20 ft or so south-east (I think) of the main impact hole. Unless the emergency services hacked that hole for access, it is an impact mark, and given the way the machine was facing it is the initial impact mark.
Now I have only done three helicopter accident investigations and I have never used my qualification in structural engineering before becoming a professional pilot, so is there anyone who can explain how that hole came about? Or am I misreading the video of the roof as seen when the aircraft was removed? Quite happy to be told that I am and I will revise my opinion of what happened here.
I said more or less the same a bunch of pages back.
One thing nobody but me seems to have commented on is the (relatively) small hole in the roof about 20 ft or so south-east (I think) of the main impact hole. Unless the emergency services hacked that hole for access, it is an impact mark, and given the way the machine was facing it is the initial impact mark.
Now I have only done three helicopter accident investigations and I have never used my qualification in structural engineering before becoming a professional pilot, so is there anyone who can explain how that hole came about? Or am I misreading the video of the roof as seen when the aircraft was removed? Quite happy to be told that I am and I will revise my opinion of what happened here.
Perhaps it was a night auto as a result of some mechanical failure and initially a verticalish, level descent. Then the pilot misjudges the height to cushion (not difficult in those conditions) and either uses up all the NR leaving a short fall to the roof with little cyclic control or, pulling hard as the skids hit the roof, actually gets airborne in a bounce and then the second landing (again with little NR or control) is what actually breaks through the roof.
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I've just watched an interview with a chap who was on the top of the car park. He states he heard what sounded like a car backfiring but ten times louder, looked all around, turned back to the way he was facing and realised in was a helicopter.
He then stated quite clearly he watched it tumble out of the sky front over end (cab over tail rotor) a couple of times before hitting the pub.
He then stated quite clearly he watched it tumble out of the sky front over end (cab over tail rotor) a couple of times before hitting the pub.
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Something else to consider...
Hypothetically, if ac was spinning violently with little remaining fuel in the tanks, would the fuel pool outwards, away from the tank pickup and starve the engines?
Hypothetically, if ac was spinning violently with little remaining fuel in the tanks, would the fuel pool outwards, away from the tank pickup and starve the engines?
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TC
Pertinent post as usual. Had thought of the Sabotage option, though that would still have needed to be effected somehow. Sudden pilot incapacitation from a gunshot? And you did indeed get me thinking about another S option too ....
After five days with no type grounding, emergency ADs or other maintenance advisory info, the cause options are probably fairly limited. It is surely hard to think of a mechanical failure cause that would not have precipitated some emergency action, even if just checking something.
Pertinent post as usual. Had thought of the Sabotage option, though that would still have needed to be effected somehow. Sudden pilot incapacitation from a gunshot? And you did indeed get me thinking about another S option too ....
After five days with no type grounding, emergency ADs or other maintenance advisory info, the cause options are probably fairly limited. It is surely hard to think of a mechanical failure cause that would not have precipitated some emergency action, even if just checking something.
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Firstly to Sawman - Many thanks for taking the time to give us your professional opinion and detailed analysis on the construction and load bearing capacity of the building's roof. I for one found it a very useful insight.
Secondly, many people have speculated on the pilot's possible choice of emergency landing site, or that he may have mistakenly thought it was a flat area or a car park etc. if it is to be considered that this was a controlled, or partially controlled forced landing. One thing no one of this opinion appears to have considered is that he knew the area well from having spent over 4 years working at the Glasgow unit based a couple of miles from the crash site. I am sure he spent may an hour hovering over the city centre, in which case he would have known not only the layout of the city intimately, but many of its prominent buildings well also.
I know that when I am tasked to an incident in an area I am familiar with, I firstly consider the immediate surroundings, and often discuss this with my crew before getting airborne, the more experienced of whom are often also very familiar with the incident location and immediate surroundings too.
I think it unlikely that regardless of whether the pilot spent much time in Glasgow when off duty that he would not have known the layout of the buildings in the vicinity of the crash site, adjacent to a major road junction and bridge over the Clyde. Also bear in mind that he had been orbiting around close to this area whilst on task for the previous 2 hours and I am sure would have been spatially aware of his position at all times.
Secondly, many people have speculated on the pilot's possible choice of emergency landing site, or that he may have mistakenly thought it was a flat area or a car park etc. if it is to be considered that this was a controlled, or partially controlled forced landing. One thing no one of this opinion appears to have considered is that he knew the area well from having spent over 4 years working at the Glasgow unit based a couple of miles from the crash site. I am sure he spent may an hour hovering over the city centre, in which case he would have known not only the layout of the city intimately, but many of its prominent buildings well also.
I know that when I am tasked to an incident in an area I am familiar with, I firstly consider the immediate surroundings, and often discuss this with my crew before getting airborne, the more experienced of whom are often also very familiar with the incident location and immediate surroundings too.
I think it unlikely that regardless of whether the pilot spent much time in Glasgow when off duty that he would not have known the layout of the buildings in the vicinity of the crash site, adjacent to a major road junction and bridge over the Clyde. Also bear in mind that he had been orbiting around close to this area whilst on task for the previous 2 hours and I am sure would have been spatially aware of his position at all times.
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Fleet Grounding
Hi
I wonder if Fleet grounding depends on safety issues or business/customer pressure, as we have had recent samples on how this works.
If there was any mechanical failure must be very specific to avoid any warnings.
I wonder if Fleet grounding depends on safety issues or business/customer pressure, as we have had recent samples on how this works.
If there was any mechanical failure must be very specific to avoid any warnings.
Thinking that for whatever reason the drivetrain was disrupted so no power getting to the rotors. If the drivetrain was disrupted enough it could cause misalignment or unseating of the swashplate/pitch control mechanism. This could mean that the aircraft was unable to enter self-sustaining autorotation and therefore the flight turned into a race between an emergency descent and a steadily decaying MR rpm. Realising that the MR rpm is now way below min. auto rpm, and the aircraft is descending very rapidly towards the roof, the pilot makes a last heroic attempt to level the aircraft and pull whatever meagre amount of pitch is left. sadly not enough and the aircraft falls through with stopped rotors?
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Thomas Coupling, hi.
You are one to whom I referred when I pointed out there are some extremely well qualified posters here. However, I have to disagree that there is much evidence that the aircraft struck the roof in a nose down attitude. I accept you used the term 'appears'.
Of course you, and others, could be correct, but there is little if anything to rule out the scenario whereby the aircraft had a largely level body attitude on impact. The reason the aircraft penetrated the roof in the attitude it did, is very likely to have been caused by the presence of a significant structural feature within the building which supported the rear of the fuselage.
My main observation is that any catastrophic failure is traditionally followed by mandated groundings, and type inspections. Have there been any such requirements?
You are one to whom I referred when I pointed out there are some extremely well qualified posters here. However, I have to disagree that there is much evidence that the aircraft struck the roof in a nose down attitude. I accept you used the term 'appears'.
Of course you, and others, could be correct, but there is little if anything to rule out the scenario whereby the aircraft had a largely level body attitude on impact. The reason the aircraft penetrated the roof in the attitude it did, is very likely to have been caused by the presence of a significant structural feature within the building which supported the rear of the fuselage.
My main observation is that any catastrophic failure is traditionally followed by mandated groundings, and type inspections. Have there been any such requirements?