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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 26th Feb 2009, 21:00
  #521 (permalink)  
 
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In 2000, several drop tests of 737 fuselage sections were conducted at the FAA William J. Hughes Technical Center.

30-ft/s vertical velocity (1800 fpm) onto solid wood base, with no lateral, longitudinal, or rotational velocity components.

Max accelerations recorded varied from 11 to 36 g's depending on what/where the measurement was being made and differences in nearby structure.



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Old 26th Feb 2009, 21:05
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FEHoppy, yes I do! If this aircraft would have landed with 4000ft/min there wouldn't be anything left except powder! btw 83kts is most probably ground speed. The fact that this aircraft couldn't impact with 4000ft/min is a sign that these transponder data are not correct.
You need to slow down and look at the data mate. This position is about 250 meters north of the resting place of the wreck. The aircraft is still airborne. Now put this into a picture of an aircraft attempting a stall recovery. As it continues the vertical speed reduces but not enough to prevent impact. The actual vs just prior to impact could be rather different.

PS. 4000ft/min is about 20 m/s
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Old 26th Feb 2009, 21:07
  #523 (permalink)  

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Dani and Rainboe,
The survivability of a crash depends on g forces...and the way these forces are spread at the instant of the crash.
You both concentrate - rightfully - on the stopping distance, but it's only one aspect of what happened.
My opinion - and it's just my opinion - is that the distribution of the deceleration forces played a significant role :
The way I see it
1/ They hit the groung tail first, beginning a structural absorption of said forces (the energy is spent partially in bending the tail and shearing the stabilizer).
2/ With some of the kinetic energy already spent, some is further absorbed by the mud and shearing the landing gears off.
3/ When they hit the ground after a fuselage rotation around the gear struts, the inertia of the different parts of the fuselage, especially those ( the parts of the cabin on both sides of the wing root ) in a cantilever state. The shearing/compressing energy involved broke the fuselage into the three pieces we can see.
4/ the farthest point away from the de-rotation would be the cockpit, also with the greatest deceleration. The part that was subjected to the second most important decel will be the one just abreast of the landing gear...
In other words, the structure deformation/failure absorbed most of the crash energy, which apparently wasn't very important (that's relative...),considering the slow speeds involved.
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Old 26th Feb 2009, 21:09
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autothrottle issue?

the issue with the autothrottle seems plausible -
fully configured at 3nm in approx. 1000ft with F30 and being distracted by heavy training on the flight deck on final approach, speed starts dropping and nobody realises that the A/T is off. aircraft gets upset and descends below glide directly into the wake of the preceding 757 (observed by the pax as turbulence), which could make a recovery well below 500ft impossible...
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Old 26th Feb 2009, 21:12
  #525 (permalink)  
 
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jupilair

You state "sadly" that in the Turkish culture a go-around is not an option.
Is this forum a place where we can talk almost anything about people, countries, their culture etc.? It is interesting that you think you have the right to blame a country's culture with careless phrases. But no! You do not have the right!
Aviation in Turkey is being conducted (like in all other western countries) under strict rules. An indication for a go around in New York is not different form an indication for a go around in Trabzon!
A go around IS an option in our culture if the conditions warrant it. Please be careful when talking about people and their cultures. And you better do not talk about anything you are not familiar with.
As you see, I haven't commented on your (IMHO very nonsense) explanation of the tragic accident. But I would suggest that all posters try to concentrate on facts and do not try to blame someone or a whole land without any objective evidence.

Last edited by sumeryamaner; 26th Feb 2009 at 21:16. Reason: Spelling
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Old 26th Feb 2009, 21:30
  #526 (permalink)  
 
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Quote:
Originally Posted by golfyankeesierra
Quote:
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...
Not disputing your subsequent points but where have you actually seen/read him say that? I watched RTL Nieuws and read several articles earlier and couldn't find any evidence he'd actually said that. The closest I could get was the piece I translated earlier where he quite clearly said he thought the aircraft had stalled.
You're right, he never said the engines stalled. He said something like that the engines probably weren't working otherwise the passengers would have heard them after which the interviewer concluded they were not working.
He said it in the NOVA interview
It more and more seems to be a stupid remark for an "accident investigator".
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Old 26th Feb 2009, 21:36
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two repairs at the crashed a/c in the last 2 months

A Turkish newsletter reports, that there have been two repairs (out of regular maintenance) at the crashed A/C in the last 2 months.

But no word about of what kind this "repairs" were ... ???

Maybe a typical newsletter "catch-line" or a new hint ...
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Old 26th Feb 2009, 21:42
  #528 (permalink)  
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Repairs

Details of the repairs (including Master Caution Light) are provided in press release 3 by Turkish Airlines on their website. It's been badly translated but I guess it will mean something to you guys. Here is the link:

http://www.thy.com/DarkSiteEN/press.aspx
 
Old 26th Feb 2009, 21:42
  #529 (permalink)  
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(I've read through all posts)
Some comments:
Seems to me like the foward fuselage failure (break apart) is due to buckling. If you see the foward part of the break up area is also turned inwards, and it's more visible on the left side pictures. Even more in the front close to the cockpit there are buckled sections.
If you see the inside of the fuselage (the inside window frames) are also moved foward (caompare the outter frame with the inner frames).
I think the nose plunged down in the mud and 'stopped' puting huge loads that failed the fuselage by buckling. I think the worst place to be in that plane would be front rows, infront of the front break up.
The break up of the tail may not be that severe, things that are allowed to break apart, take their energy withthem and don't develop high g loads.

The things protruding out behind the cockpit are also strange and I think indicate huge forces on the front part of the aircraft. Would be good to know if cabin crew that sits in the front facing the back, straped, have survived...

In general I agree with Dani BUT I think that what killed the pilots was the muddy field. I think the front part broke at the last moments before stoping, due to the nose plunging into the mud stoping it abruptly and the fusalege failed due to buckling infront of the wing. If the nose had broken earlier (shear loads - vertical forces) from hiting the ground it wouldn't have been there.

Another note.. I doubt the forces where 2g. Things in aircraft cabins are designed not to be seperated at 9g vertical 7-9g horizontal and 3-4g sideways (as far as I remember). A318 hard landing in LCY recently was 3g nothing broke apart (aircraft has to be checked I guess).
Someone said sth like more than 2g on A/C and the A/C is damaged. No way!!! Nothing will break apart at 2-3-4g... BUT there will be cracks created and the life of the aircraft is seriously reduced. It has to do with the magnitude of the alternating load in fatigue. An aircraft at 1.5g may have a life of 30,000h at 2g it can be cut at half.

There is diffirence in what 'damage' is for an engineer and what damage is for a passanger. If passangers knew how many 'damaged' parts are in a plane they would go by boat (whoever flames back at this obviously has little depth in aviation safety issues).

Strangely I believe this was a good emergency landing (deliberate or not I don't care), defenitely sth was VERRYYY wrong before.

The thierd person in the cockpit may have been another pilot or stuff of turkish airlines, flying for free. Don't tell me it doesn't happen or that they would mention it.

P.S: There is way to much spam in this forum guys... Why are you reposting newsagencies data... We all read this...

Sorry for the long post.
 
Old 26th Feb 2009, 21:47
  #530 (permalink)  
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ADS-B Track of this flight on OpenATC.com

All,

here are the links to the Google Maps and (more interestingly) Google Earth tracks for this flight from OpenATC.com. Make sure you select the "Black Box" Mode for the Google Earth view:

Google Earth (requires Google Earth installed):
openATC Google Earth

Google Maps:
openATC Google Maps

Looks like the last three transmissions are hinting at the pilot trading speed vs. altitude until, at 83kts ground speed, gravity won and the vertical rate was up to more than 4000fpm (20m/s). Quite an impact!

Important notes for those not familiar with ADS-B:

- The speed is GPS derived, i.e. ground speed, NOT IAS!
- The altitude as well as vertical speed are pressure derived, NOT GPS! However, the altitudes are always expressed in flight levels, i.e. in reference to 1013 hPa pressure, standard sea level pressure. Hence you see the -200ft.

Last edited by ZeeDoktor; 26th Feb 2009 at 22:29.
 
Old 26th Feb 2009, 21:58
  #531 (permalink)  
 
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Turkish Airlines Bulletin

Hopefully the bulletin is only referring to press comments about a couple of defects. 2 Tech Log defects in the timescale they are talking about seems mighty few to me.
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Old 26th Feb 2009, 22:09
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Overhead Panel (P5)

Can't remember if this is hinged at fwd or aft but I remember it has a latch which catches it from dropping after you release the fasteners. It's very heavy. Anyone tell me where the hinge is?
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Old 26th Feb 2009, 22:09
  #533 (permalink)  
 
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What Dimitris has said is interesting for sure. I noticed it earlier whilst looking over photos. It looks to me that the aircraft would of continued to slide further, but the front of the aircraft has dug in, hence the front seperation of the plane. It would also explain why the middle of the aircraft is somewhat overlapping the front part of the fuselage (much like what would happen in a train crash, with the front carriage stopping and the rest of the train still in movement.)

What's bothering me are these conflicting reports. I've now read several where people have said the engines sounded like they were requesting more thrust, yet the engines seem somewhat undamaged. It just seems odd to me? Either they are completely wrong or something is not quite right here. What I was trying to piece together was if this was a chain of events rather than one overall failure. One of the engines seems almost perfect whilst the other is damaged but not as much as expected. Could if be that they lost one engine, whilst the other was particially responding? Regarding fire, as I already posted there were one or two reports of one of the engines being on fire briefly after detaching, but soon exinguished itself?

I think our theories could go on forever. Whatever the outcome it seems puzzling what has led to the incident. No Distress call which suggests something happened very quickly, both engines failing at the same time due to starvation? very unlikely is it not? It just seems like an unfortunate chain of events and possibly failures have lead to this. Looking at the posts it seems that even the professionals are stumped to what could be the cause.

I look forward to reading more information from you guys soon.

Ps. I think another evil twist of fate is that the people who could directly assist with the investigation (Flight crew and the Boeing staff) all lost their lives.

Has there been any announcements as to why the Boeing staff were on the plane out of interest? I was just wondering if they were in anyway related to the aircraft in question or just normal passengers.

Last edited by RiSq; 26th Feb 2009 at 22:21.
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Old 26th Feb 2009, 22:10
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dimitris - I believe the guesstimate 2G acceleration mentioned was in regard to the moment acting to swing the nose towards the ground after the tail contact, rather than the deceleration of the nose upon impact.
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Old 26th Feb 2009, 22:15
  #535 (permalink)  

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Originally Posted by no sponsor
-200 ft (as in minus)? This is presumably the 1013 value?
Yes. Transponders send altitude code in mode C referenced to 1013,25 / 29.92, technically it is Flight level and not altitude. The sent data give no reference to acual selected altimeter baro setting. (I have no idea if perhaps it may be available through mode S coding).

Also one other information I found possibly confusing in the thread is that there would be no terrain warining in landing configuration via GPWS. That is correct, GPWS would only have (loud enough) "GlideSlope" alert. On the other hand, Enhanced GPWS which I believe had been made mandatory for the likes of this 738 operated from Turkey, does have a mode called Terrain Clearance Floor which could have been activated. One way or another, the situation probably triggered several warnings; whichever took priority I cannot guess with my limited tech knowldege but CVR will surely reveal. Niether do I suggest that once the crew is made aware more warnings are automatically better help to solve the situation.

FD (the un-real)
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Old 26th Feb 2009, 22:19
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P5 Overhead panel

Answered my own question from The Overhead Panel
so what probably encroached on the cockpit from behind the crew was the circuit breaker panels. I was considering that it might have been the overhead panel.
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Old 26th Feb 2009, 22:20
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As a SLF only; I have been thinking about this accident and there is one strain of thought that concerns me; so I wanted to run it passed the professionals to see your views.

If an aircraft is flying along at high altitude on 1013mb and is then landing at an airfield with a higher pressure setting of 1027mb (for instance) but for some reason the altimeter is not set to the airfield setting; wouldn't the aircraft then be 420' (14 x 30') lower than the pilots thought it was?

In the Turkish airlines crash; I've read that the aircraft should have been at about 355' altitude at the crash site if it were on a normal approach.

So.... IF the aircraft were 420' lower than it should have been and then the pilots became visual with the ground after breaking cloud, and the picture wasn't what they expected, wouldn't they initiate a go-around? I've also been reading that the B737-800 can be a bit tricky in a go-around with pitch and thrust; so isn't this a good precursor for a stall? If the go-around were initiated from 420' below the normal flight path (that would be about 2-3km back from normal?) wouldn't a failed go-around and stall then put them about at the crash site?

Food for thought or just talking out my A**e?
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Old 26th Feb 2009, 22:24
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Question

What is the source of the 'fact' that the preceding aircraft was a 757? I read somewhere early on this thread that the last aircraft to land before the crash was a 757, but at that point it was unknown if it even landed on 18R. Sometime later I read on some newspaper article about this ominous 757 and suddenly its taken as a fact here in this thread, and theories of wake turbulence being the reason for the crash erupt...

So is there a verified source for this, or is this some kind of self-reference?

Last edited by jojoxy; 26th Feb 2009 at 22:25. Reason: typo
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Old 26th Feb 2009, 22:28
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From the plot on Google Earth, the rate of descent and speed are fairly normal for an ILS in a B737 until the point when they are passing the golf course to the east. From that point, the speed is decaying steadily but the vertical speed remains constant until they cross over the motorway, where the vertical speed increases rapidly as the wing stalls. Yes Dani, I said it stalled. For me, this points to a lack of thrust and an attempt to avoid striking the motorway, followed by a loss of control when the stall occurred.
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Old 26th Feb 2009, 22:34
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Rainboe

Would it not require deliberate fuel system adjustment not to drain fuel from the centre tank first? I thought all Boeing designs have higher pump output pressure from the centre tank?
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