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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

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Old 25th Feb 2009, 21:53
  #281 (permalink)  
 
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The disposal of the aircraft wreck of the Gerona (LEGE) B757 is very similar. It was also a low speed crash. The plane actually touched down at the runway but departed from it falling into a small cliff.

The Turkish B737 touched the ground tail first at very low airspeed and at a very high AOA, and then the rest of the plane became smashed to the ground getting halted in very very short distance.

I think that this is fact. Any pilot can understand it viewing the images.

Why the plane get in low speed condition is speculation, and why shouldnt we just speculate?
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Old 25th Feb 2009, 21:55
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9G ... it would not even come off the runway ... it's a transport class: 3G and you are history ...
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Old 25th Feb 2009, 21:58
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The posting of the helicopter video (and a good, useful post) shows the horizontal stabiliser is inverted - just a comment, no further speculation about the bounce characteristics of major airframe components on agricultural land and the prevailing weather conditions or the crop that has been planted. I'll wait for the report.

The three EMS helicopters in the field shows that there was an emergency plan in place by AMS. Re the earlier comment about the same thing happening at LHR, which got some stick, that would not happen, there is no such coordinated response.

As far as the special members area goes, perhaps it could be based on number of posts per day? If you get above 1, maybe you should get a life?
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Old 25th Feb 2009, 22:02
  #284 (permalink)  
 
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Quote; PS EHAM has had a NOTAM for birds for months

They all have Bird warnings as standard. Unfortunately this is just to cover their backsides and not a true assessment of the situation.
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Old 25th Feb 2009, 22:10
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The video shows an aircraft that pancaked into a field in a fully stalled, out of control, manner.
These pilots did not maintain their airspeed. They LOST CONTROL of their aircraft.
Before condemning the pilots it might be good to look at this flight path reconstruction: http://aviation-safety.net/photos/gr...090225-0-2.gif

If we were to assume a loss-of-power event, one likely scenario is that the crew tried to glide towards the airport, but didn't quite make it and had to stretch the final part to avoid hitting the N200 road which runs straight across the flight path just before the eventual touchdown. The consequence of that stretching would then be loss of airspeed and stall or partial stall.

So in this scenario the crew had the unenviable choice between hitting the traffic on the road or lose flying speed.

I have not yet noticed any witness from those undoubtedly numerous who were driving along the N200, who could say how low the plane was when it crossed the road. Tomorrow we will without doubt be wiser on this issue.
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Old 25th Feb 2009, 22:17
  #286 (permalink)  
 
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ETA was 1031, is scheduled flight, crash at 1030 I would not think it was fuel starvation.
No fire after impact due to low fuel on board and ground conditions.
Low cloud 700 and possible low vis due to fog 5 temp 4 due, ac was spot on the approach.
Bird strike very possible but examination of the engines will show straight away signs of this, and they would have been an attempt for a force landing which is not the case.
Stall of the ac is obvious, could be due to high level of automation and not in time recognition of the impending stall due to ac been in tha glide path.
Lets wait for the AIB investigation, for lessons learned.
Sad very very sad!! RIP
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Old 25th Feb 2009, 22:21
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Having just seen the last post ( no. 301), using ETA vs. accident time to derive a fuel figure, "ac being spot on the approach", and "stall of the ac is obvious", I rest my case.
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Old 25th Feb 2009, 22:23
  #288 (permalink)  
 
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Originally Posted by Strongresolve
The Turkish B737 touched the ground tail first at very low airspeed and at a very high AOA, and then the rest of the plane became smashed to the ground getting halted in very very short distance.

I think that this is fact. Any pilot can understand it viewing the images.
Any pilot except "757_Driver". He seems to disagree with this assessment.
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Old 25th Feb 2009, 22:23
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"Stall of the ac is obvious"

no-it isn't, it was seen flying high aoa, meaning low on airspeed. tail seems to have impacted first. if it stalled in flight I would expect it to have struck the grond with a low-nose attitude.
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Old 25th Feb 2009, 22:25
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This seems fairly straightforward to me (not solved, but the mysteries remaining seem pretty linear).

Aircraft on short final slows to a speed that cannot support flight. It may be very hard to "stall" a 737, but at a slow enough speed it (and anything down to the size of a Warrior) will develop a high sink rate ("fall out of the sky") even if the AOA and airflow are not in a technical stall.

Slow forward speed is consistently supported by short debris trail, witness accounts, "flat" or tail-low impact posture.

Weather reported (stable, stratus layer, no vertical development, no CNB) is not consistent with a wind-shear event (but a severe wind shear would produce similar results and appearances - at the right time of year).

Wake turbulence usually results in roll effects - this seems to be a wings-level pitch incident.

So - why was it slow?

Low thrust seems to head the line of suspects. (Witness reports of relative silence of plane, from inside and outside the hull, engine state as visible SO FAR(!!))

> Birds in engines? Not impossible (Cactus 1549, Ryanair/Ciampino).
> Fuel contamination or blockage? Could be (BA 777).
> Failure to set thrust correctly? Not unheard of. (Continental/Colgan 3407 - although still a big big MAYBE in that case).
> Fuel exhaustion? I have doubts myself - but it has happened more times than I would have expected in jetliners.

That's where the FDR and CVR come in handy. Plus DNA checks of the engines. Etc. etc. The investigation.

Now - evidence could still appear that contradicts me. Signs the engines were producing high thrust at the time of impact (physical state plus data records). Something like the magic air tank from the Qantas/Manila event - that introduces a whole new factor. We've been "surprised" by the obvious quite a few times in just the past year.

If I were on the investigation team, I'd be looking for facts. And just as happy to find ones that proved me - wrong - as proved me right.
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Old 25th Feb 2009, 22:27
  #291 (permalink)  
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In the configuration the aircraft was in, could someone with appropriate knowledge say what the stall speed would be?
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Old 25th Feb 2009, 22:33
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I have not yet noticed any witness from those undoubtedly numerous who were driving along the N200, who could say how low the plane was when it crossed the road. Tomorrow we will without doubt be wiser on this issue.
Sensible remark,

Yes witness reports of motorists on the 6-lane motorway (about 500 yards from the impact site) have been gathered and passed onto the Dutch "AAIB". Even commercial pilots saw it happen in the traffic jam.
Unfortunately (I guess) gathered in a non-english language..

...and at a suitable reporting date (if it was only for xxxxx-xxx-xxxxxx) very likely in English.

Last edited by Fokker52; 25th Feb 2009 at 23:07.
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Old 25th Feb 2009, 22:34
  #293 (permalink)  
 
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to: Feathers McGraw

Vref for a landing flaps, partially loaded 738, low on fuel, somewhere around 130. divide by 1.3 and my calculated guess is 100 knots, 185km/hr.
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Old 25th Feb 2009, 22:39
  #294 (permalink)  
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OK, so the 88kts GS, 420ft and a last recorded position N52 22.8 E004 42.8 (right where the impact occurred) I saw elsewhere would fit in as being consistent with that stall speed, IOW below it by some margin.

Last edited by Feathers McGraw; 25th Feb 2009 at 22:41. Reason: Add more detail.
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Old 25th Feb 2009, 22:52
  #295 (permalink)  
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Guppiebugs

88kts GS was the final recorded value in the software log from a guy with a Radarbox Mode-S receiver who is fairly near EHAM, and has coverage of aircraft on the ground there so would be able to receive the Mode-S from where TC-JGE was before impact.

Naturally because the position, speed and height transmissions are not all sent at the same time you can't say the three things are coincident, but they will be within a second or so I would say.

I'm just trying to give people an idea of how far below Vs they were just before impact.
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Old 25th Feb 2009, 22:54
  #296 (permalink)  
 
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AOA - Ignore any discussion about this until the facts are known from the FDR.

The untrained eye witnesses don't understand the different landing attitudes of different aircraft, so will always say "hey he was very nose up" or words to that effect.

the BA777 incident proved this, witnesses said he had a high AOA, but the reality was that the crew lowered the nose to try to get the airspeed back.
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Old 25th Feb 2009, 22:54
  #297 (permalink)  
 
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Feathers..

So running the speculation the other way would it be fair to say the Radrabox data could be wildly inaccurate and therefore all this talk of Vs is premature...just a thought?
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Old 25th Feb 2009, 22:56
  #298 (permalink)  
 
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If any bird control people could reposed. (I assume they are allowed to contribute to this forum, even under the proposed 'show me your ATPL’ rules...)

Bird Control is (in the EU) primarily within airport boundaries. Airports may have local agreements to operate outside boundaries, and will also plot hazard areas, and liase with local planners and environment agencies to try to minimise habitat impact on operations whilst maintaining a sensible ecological balance. For example netting waste disposal sites, lagoons and making areas immediately adjacent to the airfield less attractive to birds. Schipol is unfortunately in an area frequented by birds as the whole area is a natural habitat, and we are just getting to the start of many species migratory season.

I've been fortunate enough to spend time a few years ago with the AMS bird control unit and they are a highly professional, motivated and innovative unit.
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Old 25th Feb 2009, 22:56
  #299 (permalink)  
 
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"88kts GS was the final recorded value in the software log from a guy with a Radarbox Mode-S receiver ..."

amazing equipment for a hobby ...

88kts seems realistic and the high pitch (proabably) seen already indicated the low speed.

I'm off now, don't forget to correct for wind, won't be too much of it I guess.
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Old 25th Feb 2009, 23:02
  #300 (permalink)  
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Wiggy

It would be pretty close, but of course not timestamped as you would get from the DFDR or QAR. The 88kts would have come from the GPS receiver, so turning GS into IAS/TAS needs the wind component, as I recall the wind was a low figure (10kts approx?) from 210 degrees so about 25 or 30 degrees off the runway heading. That might make the IAS another 8 kts or so higher?

I wasn't intending to do anything other than provide what I believe to be quite accurate information, or point any fingers. In comparison with some of what has appeared here today I thought it was pretty tame actually.
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