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Police helicopter crashes onto Glasgow pub

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Police helicopter crashes onto Glasgow pub

Old 18th Feb 2014, 04:03
  #2221 (permalink)  
 
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I agree that "intermittent" is interesting. However, there was time for two other warnings to be recorded after that, so it implies the speed was falling earlier rather than later in the short final sequence.

The report doesn't state that there was a failure to enter autorotation. The lack of the SHED BUS switching implies it never became stable or relaxed enough to permit that to be done.

There's a few things that might illuminate that scenario -

The physical damage to the wreckage will eventually reveal a vertical speed on impact, but looks to be quite fast. The term "very high energy deceleration" is used in the report.

The helicopter landed with mostly vertical speed on a roof. That seems to be inconsistent with stretching out distance over the river. The radar track prior to the accident should make this clear.

If the 400ft radar return is from a single reading on descent, after 1000ft and before zero, then that sets a limit to the descent speed of something more than about 50ft/s, assuming a 10s scan. If some of that was more gentle, then the end has to be steeper.
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Old 18th Feb 2014, 05:39
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Old 18th Feb 2014, 06:11
  #2223 (permalink)  
 
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Sounds like skrangerpro and FlightSpanner above have put a time and position on the transfer switch error. The radar flight path shows a zigzag over Dalkeith and the main tank level was low enough to get transfer pump warnings. If both pumps were switched off over Dalkeith and then the wrong ones switched on for the return journey that would explain all.

Confusion when all the warnings came up, pilot knew he'd turned the pumps back on so had to guess at other causes.
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Old 18th Feb 2014, 06:26
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Are there maneuvering limits imposed on the 135 once the mains are down to 0kg and both XFER pumps are selected to off? If you nose her over a bit too enthusiastically would some of the fuel in the supply tanks spill over the wall and back into the main tank?

As for the reported "tumbling" (nose over tail) by one eye witness can we discount that once and for all as it would be a difficult maneuver to achieve even with a perfectly controllable helicopter (ok, I've seen a solitary backflip at an airshow but that needed plenty of skillful purposed flying to achieve), and bits of helicopter would start departing after the first few uncontrolled "tumbles".

My take on this is that there must have been some kind of major conflict between the fuel status display on the computer screen and the captions/gongs that were going off. I'm sure this experienced pilot knew there was enough fuel remaining to comfortably get back to base so perhaps figured that with 2 out of 3 in his favour he had time to troubleshoot the fuel problem. Is there a chance he could have turned the XFER pumps on then off several times in his battle to get at that remaining fuel to silence those captions/gongs only to be greeted with even more erroneous and confusing behaviour by the fuel status displays, or they had frozen indicating useable quantaties from several minutes ago, until it was all too late.

As I have said before I feel he did enter into an autorotation successfully, but all autorotations carry significant difficulty and risk, even more so at night.

Last edited by cattletruck; 18th Feb 2014 at 07:15. Reason: added more about my distrust of computers
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Old 18th Feb 2014, 06:59
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We probably can discount "tumbling". Could the witness discriminate between yawing and tumbling?

However, if there was no rotor speed, it would be physically possible. With rotor speed it's not physically possible, as the torque required to change the direction of the rotor axis quickly is too large to impose.

If the report is correct, then it does give some information after the accident.
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Old 18th Feb 2014, 07:12
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I'm sure this experienced pilot knew there was enough fuel remaining to comfortably get back to base so perhaps figured that with 2 out of 3 in his favour he had time to troubleshoot the fuel problem..
I think the very fact he had only ~75Kg's of fuel left kind of blows that theory out the window, unless it's std practice to land with below min fuel?
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Old 18th Feb 2014, 07:20
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75kg is enough to physically get to back to base from where he was, but in a not so perfect police patrolling role of being tasked unpredictably he was not too far under the minimums and definitely not in a crisis situation.
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Old 18th Feb 2014, 07:31
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Sid, what about the red string!
Unfortunately, there is no red string on a 135. A major design flaw in my opinion.
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Old 18th Feb 2014, 07:59
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Sounds like skrangerpro and FlightSpanner above have put a time and position on the transfer switch error. The radar flight path shows a zigzag over Dalkeith and the main tank level was low enough to get transfer pump warnings.

Henry: Is this strictly true? I've read this thread and the EC135 thread particularly post 83 and I've seen slightly conflicting views on the fuel level at which transfer pump warnings appear, hence my earlier question.

I think the position has been worked back from the endurance of the supply tanks once they are no longer being replenished by either i) overall fuel level above the fence, ii) sloshing over the fence or iii) transfer pumps operative.

Last edited by catch21; 18th Feb 2014 at 09:27. Reason: "this thread" instead of "the thread"
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Old 18th Feb 2014, 08:03
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Wageslave: The first thing that struck me was the Nr warning described as "intermittent". That surely is significant. An intermittent Nr warning suggests Nr alternating just above and just below the min limit (whatever that is). It does not seem to indicate a single failure to reduce collective, ie a failure to establish an autorotation. It is far more characteristic of someone milking the Nr for range to the limit.
Very interesting observation!
I found (albeit for a EC135 P2+) :
low rpm warning at <= 97%
minimum transient (<20s) power on rpm to be 85%
minimum cont. power off rpm is 80% (at GW < 1900kg)

At what low rpm would the airflow over the blades begin to stall, assuming max. range "gliding attitude", with 3 people, police gear (FLIR?) and low fuel ?
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Old 18th Feb 2014, 08:54
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MightyGem,

Simple days.....red string....one fuel tank.....no SAS or AP....handful of guages, now look where all this gagetry has got us!

JAFO, good to hear you're still at it. Guess you've got to be there to know how the modern pilot/crew/passenger thing pans out at the coalface. Not enough time or willingness to preach to the never to be converted. Different era's my friend.
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Old 18th Feb 2014, 09:11
  #2232 (permalink)  
 
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Henry Crum, catch 21...and others.

I do think you, along with others have worked out a very plausible start point for the error that led to the flame outs. We still haven't a clue why no actions were apparently taken to respond to the many warnings of the worsening situation.

Scuffers, it most certainly is not the standard practice to land with less than MLA fuel, it's not something that can be covered up. The police crew would be aware of it (they are an integral part of the challenge and response pre-landing checks and the refuelling process, and it would require collusion to falsify the tech log records....not something the police are going to do. If it did land with less than MLA, I would expect an MOR to be raised and a degree of de-briefing from management to take place. We still have no evidence that Dave knew he would land with less than MLA though I agree that the flight time suggests strongly that would be the case.

For those that missed earlier posts, the EC135 training manual indicates the fuel system can be up to 6% fuel quantity in error under normal operating conditions. This does provide a margin that means we may never know exactly what figure were displayed in the cockpit.
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Old 18th Feb 2014, 09:24
  #2233 (permalink)  
 
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crew input

TR

on the Kegworth 737 I recall the CC did exactly that & the pilots shut down the wrong engine !

sorry to move off thread but you started it !
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Old 18th Feb 2014, 09:39
  #2234 (permalink)  

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JAFO;
While this was a single pilot aircraft, three very experienced people were watching this happen and that makes very little sense to me.
Tr;
Come on guys.
Only one of these three 'very experienced people' (were they?) was a pilot! TFOs can be keen and knowledgeable, but they aren't professional pilots. They don't HAVE to be keen and/or knowledgeable on aviation. (Do they pass tech exams on the EC135???) They just have to fulfil THEIR role!

If you want to make a case for 'many eyes', then you need a second pilot. I'm afraid it's that simple! Don't you dare try to fudge the issue.

Either accept you're happy with one pilot making all the aviation decisions and soaking up all the pressure, or provide a second! To pretend otherwise is unfair on the police officers on board!

That's not right!

Next you'll be expecting hosties to express opinions over engine failures in jetliners!
SS;
Oh dear Tandem, you'll be telling us they are just passengers next
Tr;
Oh dear silsoe, you'll be telling us they hold a JAA licence on the EC135 next!

If you want a second pair of eyes on the flying sh1t, employ a second pilot. Otherwise accept that one person soaks up all the pressure!

One or the other!

Even hosties aren't passengers. They even do CRM! EVERYBODY knows that don't they??
Blimey tandem, I do wonder about your experience in these matters.

When I used to be an aircrewman, there were often times I would sit in the front, even sometimes without duals fitted. Sometimes I would be in the back, winching or abseil dispatching for example, (or if the senior pax wanted the front seat, until that matter was addressed!)

We didn't do CRM back in those days, but I'll tell you one thing for nothing, if I or any other of my fellow aircrewmen were flying with either an old sweat or new chap, were to see any low fuel warnings or see the fuel running a bit low, or anything not quite right, don't you think we might say something? Do you not think that might have been 'part of our role'? Even back in those days it was realised that you don't have to put someone through a whole pilots course for them to be a 'second pair of eyes'.

I think we all know that hosties aren't classed as pax and that they do complete CRM training, but don't you think that if when delivering a brew or meal to the flight deck, on seeing some warning lights and the word FUEL, they might just say something despite not being a licensed to fly that type?

Even passengers in the role of passenger with no CRM training, when seeing something not quite right, would tend to say something don't you think?
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Old 18th Feb 2014, 09:47
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on the Kegworth 737 I recall the CC did exactly that & the pilots shut down the wrong engine !
Nice one.

That accident occurred in Jan 1989.

Now here's a quick question for you: since then, how many police aircraft have been lost in air accidents in the UK?

Here's the answer, and it makes pretty ugly reading considering the relatively small number of hours flown:

EIGHT !

Now some of you would sound far more convincing suggesting everything in the garden is rosy, and you can't learn anything about flying, if only the figures supported your arguments.

There are one or two intelligent contributors on here. Just spend a little time thinking about those figures before replying.

Flight Safety is a process. A 'journey' if you like. Some of you talk like you've reached the 'destination'!
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Old 18th Feb 2014, 10:05
  #2236 (permalink)  
 
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Post Kegworth a BALPA rep was interviewed on television and stated categorically there was no way that the crew had shut down the wrong engine. I think it's best to let the AAIB get on with their job and be patient.
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Old 18th Feb 2014, 10:59
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Perhaps some guys here should read about the Hapag LLoyd landing in Vienna, 12 July 2000.

The most experienced Pilot of the airline with umpteen k hours, pressed on despite low fuel warnings from the analogue gauges, which showed information in contrast to the FMS, which said 'there is enough fuel'. And he pressed on despite a very unhappy young copilot who would have gone for the right option: land asap as information did not match up - and fuel was certainly low. Reason: The FMS didn't calculate extra drag from the gear which could not be operated after takeoff. The cptn 'believed' it did, the copilots serious doubts were not listened to.

It might not relate directly to this story. But some of the 'thinking' involved and stress responses might relate very well to what happened here; also, some technical issues have been the start of a chain of cognitive errors.

Regarding the 2 pilots discussion, I've read this again and again: The police does their job, we do ours…by no means the officers should be pilots or be involved in aviation tasks... Double standards now by any chance?

FYI the captain of HF 3378 received a suspended sentence. Loss of license, end of career, not sure if insurance wanted money back for the wrecked A310.
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Old 18th Feb 2014, 11:00
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Originally Posted by Art_Of_Flight
Scuffers, it most certainly is not the standard practice to land with less than MLA fuel, it's not something that can be covered up. The police crew would be aware of it (they are an integral part of the challenge and response pre-landing checks and the refuelling process, and it would require collusion to falsify the tech log records....not something the police are going to do. If it did land with less than MLA, I would expect an MOR to be raised and a degree of de-briefing from management to take place. We still have no evidence that Dave knew he would land with less than MLA though I agree that the flight time suggests strongly that would be the case.
What I am trying to get at here is that if the 400Kg's initial fuel load figure is correct, (ie. some ~150Kg's below topped tanks) and given a pilot experienced in Police work of this nature would have a pretty good idea of what his endurance would be, why would you:

1) not just start with a full fuel load knowing that you could be called on to divert, etc at any time and thus give you the maximum flexabilty?

2) not aim to be back on the ground well within MOP limits? (I would have more sympathy with this if he had been in rural airspace with plenty more options to put down in a fuel emergency and further away from base.)

yes, you're quite right, without data recording, we just don't know what he was looking at, however, as a total non-pilot type looking at it from the outside, I find it impossible to understand how he managed to miss all the warnings/signs of fuel starvation and not at least go for the Xfer pumps even if the gauge was showing zero (what have you got to loose?)

The other bit I can't get my head round is that he much have been aware he was in strife before asking for clearance?
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Old 18th Feb 2014, 11:16
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Anybody come up with a figure for the `actual` take-off weight with 400kg fuel,as to % of MTOW..?
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Old 18th Feb 2014, 11:22
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Ericferret

well a BALPA rep would say that wouldn't he ?

we are moving off thread here, again.......
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