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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 26th Feb 2009, 20:30
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Dfdr & Cvr...

Dani
The assertiveness of your statements regarding this accident seem to imply that at this stage of the investigations you have a certain background knowledge and/or other AAIB related skills and experience. E.g. elaborating on the deceleration behavior of “an object”, e.g. “an aircraft”, on water compared to wet/humid soil should incorporate knowledge about Newtonian liquids, i.e. water, compared to the viscous behavior of wet/humid soil with a potential non-linear behavior. While studying your public profile, your non-tech skills seem to be excellent but it lacks of hard core tech skills.
Now an airline pilot, having spent myself 9 years at university before, earning mechanical engineering degrees with specialization in structural and aerospace engineering plus 10 years of experience in said industries do not put myself into the position to issue such statements based on pictures, youtube videos and other media. Media items are certainly an intrinsic part of an AAIB investigation but the hard facts are on those disks and they will tell us the true story. This is a professional pilots network and not a newspaper.
FI
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Old 26th Feb 2009, 20:31
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Hot-and-high, thank you so much for your informative post. I agree with you completly. When you talk about a stalled aircraft then it implies that the aircraft as a whole stalled, not only parts of the wing or a stabilizer. That's why I say it's completly nonsense to talk of a stalled plane. You can stall an aircraft in any speed (even at cruising speed).

So we are coming to the point of "high ROD". Of course it must have been higher than normal (so the passenger tell us). But it cannot be really high, otherwise there wouldn't be any passenger left to explain us. I stay with the version that this was a relative soft landing.

Rainboe, the tail hit the ground at a relatively early stage of the crash landing. Granted. That doesn't mean that it was a "tail strike" landing and it's associated low speed. It could also stem from the fact that during touchdown, the main gears where burrying themselves into the soft ground. btw we don't even know if the gear was out (although they most probably where). Good pilots also know that during certification flights, aircraft have to touch the ground with the tail and still able to fly (minimum unstick speed tests). And last but not least: The spot where the tailplane lies is most probably not the point of first impact into the ground, the traces must have started before - the landing "roll" was even longer than appears from the wreackage location.

I'm not here to discuss the reason for the accident. We simple cannot discuss it here because we have no clue. I just started to take part in the thread because some obvious facts are disregarded.

Flare-idle, my knowledge comes from the intensive lecture of accident bulletins and visits of actual crash sites. It is relatively easy to tell the ROD by watching the wreckage. Please compare similar accidents and look at aircraft that really were "falling from the skies", stalled or flew into terrain. Good luck.

So, please, I'm still accepting bets...
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Old 26th Feb 2009, 20:32
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Fuel temperature a problem after 3 hours flight?????

Rubbish.
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Old 26th Feb 2009, 20:32
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I know that the engines don't show as much as damage as they could, but I find interesting that at least the right engine stoped in a very similar orientation as the plane. With the wide opening to the front. Maybe its is only coincidence, but I think it is odd after travellling dozens of meters (there is some picture taken from the highway, depicting apparently the engine going forwards and leaving a dust trace), through soft ground. Could it be due to the gyroscopic effect?, then the blades may have beeing turning.
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Old 26th Feb 2009, 20:34
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Last edited by Rainboe; 17th May 2009 at 18:34.
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Old 26th Feb 2009, 20:34
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Nick14 22/10/08

Says
Ah, guess im not standing much chance at 211 hrs then, oh well, at least im trying good luck guys Nick
Four months ago nick you were a wannabee.

My guess is that you have at least 400 hrs in your log book now.

Do us a favour and just read the posts rather than giving it the experienced 738 pilot routine.
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Old 26th Feb 2009, 20:39
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The the length of a complete 737-800 is about 39 meters long. What do you estimate the stopping distance to be?

I say 60 meters....


Last edited by Lost in Saigon; 27th Feb 2009 at 02:29.
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Old 26th Feb 2009, 20:39
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Last edited by Rainboe; 17th May 2009 at 18:34.
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Old 26th Feb 2009, 20:40
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Pieter van Vollenhoven told Dutch state television that the way the aircraft fell directly from the sky suggested that its engines might have stalled.
I would like to put the Investigation Board's chairman Mr van Vollenhoven's remarks into perspective.

He is NOT an investigator nor an aviation professional.
He is a member of the royal family (married to the Queen's sister) and somehow it seems to be a honorary job.
It also seems to me that he enjoys being in the spotlight.
Nevertheless he has done it for quite some time and is not much criticized.

Still I think his remarks are premature and more born from a desire to answer questions then from known facts.


Another thing today mentioned on interviews with survivors on dutch TV: they are already contacted by American (sic!) lawyers to be "represented".
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Old 26th Feb 2009, 20:40
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Quote by Rainboe:
As I said earlier, the mechanics of how the ground contact actually occured and what the stall state are irrelevant. It's what caused the aeroplane to fall out of the sky that matters, not how it did it.
Correct! We cannot discuss the cause of the accident because we don't have the evidence.

I just want some posters to stop ludicrous assumptions and allegations that clearly are disproved by the pictures.

Dani
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Old 26th Feb 2009, 20:45
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Dani, agreed your point about a “stalled plane” – I now understand what you were saying - sorry if I was a bit micky-mouse in my post but I guess it explains it for anyone who may be interested!

Fireflybob,

I always understood that at the stalling angle of attack the wing was generating MAXIMUM lift (or Coefficient of Lift more accurately, CL)!
Fully agreed - for a wing of constant profile across the span! And, after the Critical Angle is reached, the reduction in Cl (or Lift) is rapid. Apologies for the nurdish aerodynamics coming up. All I was trying to explain was that the angle of incidence of the wing root is designed to be greater than the angle of incidence at the wingtips. This is to force a stall to develop (ie Critical Angle to be reached) at the wing roots first as the Pitch Angle of the aircraft progressively increases. For a given Pitch Angle, AOA will progressively reduce towards the wingtips. Therefore, simplistically, half way to a fully stalled wing, the tips will be probably be unstalled, mid span will be partially stalled, and the wing roots, fully stalled. The net result is a partially stalled wing! This was to explain why Dani’s implied on/off stall description does not hold water - but I now understand what he was getting at!

Obviously, the rate of Washout determines the rate of progress of the stall outboard as Pitch Angle increases – and, of course, I use Pitch Angle loosely as, clearly, with washout, AOA varies across the wingspan for any given Pitch Angle. While PA and AOA are not the same, if you include Relative Air Flow, they are linked. As I said, once the CA is reached, the reduction in lift is very rapid while drag continues to increase, but CA is reached at the wing root first and then spreads outboard as Pitch Angle increases (assuming constant RAF!!!)

Do I qualify for a Nerd Award? Fireflybob, I hope that clarifies(!!!) what I was trying to say – clearly, rather badly in my last post!

H ‘n’ H
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Old 26th Feb 2009, 20:46
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Lost in Saigon, lost the Plot??? 60meters? Even the first debries lie more than double away from the wreckage than the whole plane length! Take into account that also the debries have an inertia and continue to move forward. You don't see the traces on the ground from that distance, and the traces have to start before the first debrie.

Ah, I forgot, you think that the aircraft had no forward speed...
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Old 26th Feb 2009, 20:48
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I just want some posters to stop ludicrous assumptions and allegations that clearly are disproved by the pictures.

Dani
like the ludicrous assumption that mode s transmits averaged data.
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Old 26th Feb 2009, 20:49
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Do I qualify for a Nerd Award? Fireflybob, I hope that clarifies(!!!) what I was trying to say – clearly, rather badly in my last post!
Hot 'n' High, not at all - I feel we are singing from the same hymn sheet!
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Old 26th Feb 2009, 20:50
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Last edited by Rainboe; 17th May 2009 at 18:35.
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Old 26th Feb 2009, 20:51
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Mode S data is not averaged. The transponder has multiple inputs, fed from sources such as air data computer, FMS, etc. These arrive at the transponder concurrently and are emitted together. There will be some time skew but not significant in this context.
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Old 26th Feb 2009, 20:51
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Come on guys, be serious, Fuel icing is not an issue here.
Anyone trying to sell that one doesn't fly commercially.

Wing icing due to cold fuel on ground, yes, especially on the NG, but that is irrelevant to this accident.
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Old 26th Feb 2009, 20:53
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yeah but when the last data burst goes out during touchdown it clearly doesn't transmit the last air speed... Most probably the cockpit was the last part of the aircraft that stayed intact and thus could still send data while the aircraft had "landed" already!
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Old 26th Feb 2009, 20:53
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Dani -
Good pilots also know that during certification flights, aircraft have to touch the ground with the tail and still able to fly (minimum unstick speed tests).
Ah...but that's done on take-off, not landing.

BTW, you have a PM.
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Old 26th Feb 2009, 20:55
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Originally Posted by Dani
Lost in Saigon, lost the Plot??? 60meters? Even the first debries lie more than double away from the wreckage than the whole plane length! Take into account that also the debries have an inertia and continue to move forward. You don't see the traces on the ground from that distance, and the traces have to start before the first debrie.

Ah, I forgot, you think that the aircraft had no forward speed...

I estimate the stopping distance to be where the tail first contacted the ground, to where the tail would have been had it still been properly attached to the aircraft.

About 60 meters...


Last edited by Lost in Saigon; 27th Feb 2009 at 02:26.
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