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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 26th Feb 2009, 12:43
  #381 (permalink)  
 
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Probably they where in IMC Wx conditions before they crash but an EGPWS call "Pull up terrain" should have save them from crashing so we can exclude that as well.
GPWS considers the A/C landing with gears down, and this inhibits the mode 2(excessive terrain closure rate/PULL UP) operation.
Anyway, the system only alerts if the terrain closure rate exceeds a certain value.
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Old 26th Feb 2009, 12:55
  #382 (permalink)  
 
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No EGPWS Alert on a coupled ILS Approach

Jagohu said (in post 356 )
"I don't really know about this A/T disconnect theory - if you go below the GS you'll get the GPWS alert straight away, so I guess you'll notice it, don't you? Not talking about the altitude alerts of the GPWS."
.
The theory in post 348 was that the a/c stalled whilst on a coupled ILS and because the "non auto-throttled" autopilot was maintaining the ILS glideslope at the expense of speed (i.e. kinetic to potential energy) - and not dropping below it and triggering the EGPWS alert.
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Old 26th Feb 2009, 12:59
  #383 (permalink)  
 
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The ground was basically flat for a great distance in every direction. There was no need to make any decision to clear the road/trees. That was a very minor obstacle to a 737-800.
That's not quite true. I'm very familiar with that area and to be honest, if the pilots had any decision room left at that stage, they made the perfect decision as to where to land the plane.

About one kilometer earlier and they would have crashed on a dual-track railway line or the N200. The N200 is a dual-carriage motorway which sits in a depression at that point, with elevated entries and exits leading to a complicated 3-level junction ("Rottepolderplein") about 500 meters right of the flightpath. Immediately after the N200 they would find a few industrial buildings and then the "Ringvaart", a 40-meter wide canal with straight edges.

To their right, about 500 meters, would be the 6-lane highway A9, running almost exactly parallel. Again, the A9 sits at an embankment about 5-8 meters above the surrounding terrain, and is very busy at all times during the day. At the other side of the highway you'll find an industrial area.

To their left they would have some 300 meter clearance to some farms, and a little more clearance to the town of Zwanenburg. But this area is cris-crossed with small ditches, 3 meters wide at most, and a few farm roads that are slightly elevated above terrain level. And the farm roads are lined with trees whose stumps are about 30 centimeters in diameter.

A kilometer later and they would have hit the A9, who makes a 30-degree turn at that point bringing it under the 18R approach path. From memory, the embankment here is again about 5-6 meters high, since this 30-degree turn in the highway coincides with the "Haarlem Zuid" exit which is a rather complicated exit with multiple viaducts.

I agree that tops of the trees that line the N200 and the Ringvaart are not really obstacles to worry about in this scenario. But these canals and embankments, and the stumps of the trees lining the farm roads are. And the field where they crashed was virtually the only place where you could hope to put an aircraft down without hitting any of those.

Edited: Fokker52 provided this link:
from: 52.377339,4.711719 - Google Maps

Unfortunately Google Earth doesn't show the relative elevations of the various roads.

Last edited by BackPacker; 26th Feb 2009 at 13:48.
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Old 26th Feb 2009, 13:00
  #384 (permalink)  
 
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I would just like to add that after listening to the ATC files at the time of the crash the Dutch controllers seem a very professional group, kudos to them in what must be very demanding circumstances.

Could some kind soul point me in the direction of these files ??

Thanks
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Old 26th Feb 2009, 13:03
  #385 (permalink)  
 
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snowfalcon2 ". . . the crew had the unenviable choice between hitting the traffic on the road or lose flying speed."
If and when you become a pilot, it will become instinctively obvious that it's always better to make a "controlled" crash as opposed to an "uncontrolled" crash by stalling and diving out of the sky.
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Old 26th Feb 2009, 13:05
  #386 (permalink)  
 
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Traces of debris

A rough look at the traces of debris behind the aircraft as well as the explanations of passengers reveal that the plane hit the ground with close-to-zero horizontal speed, which might have prevented a fire.

Might there be a possibility that the captain, once he was absolutely sure that he would crash, has decided to deliberately pull up excessively to create stall, reduced the airspeed and hit the ground without dragging on the ground so that there would be a minimum level of horizontal friction (Which, in turn, prevented rupture of fuel tanks) but resulted in a heavy (Heaviest actually) impact to occur at the nose? (Cockpit)

Such a heavy impact that although no visible damage is seen from the outside, all the stuff under the cockpit to be pushed down into the cockpit, killing all the pilots, instead of 120+ passengers to burn in fire?

Very recently I have talked to a professional pilot who knows the captain very well, and he said that such a probability is very, very high.

Any comments from pros?
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Old 26th Feb 2009, 13:15
  #387 (permalink)  
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Auto Throttle Disconnect

Is it possible for the auto throttle to disconnect while flying an auto coupled ILS? If so, is there no warning chime or other indication? I am not a 737 jockey.
 
Old 26th Feb 2009, 13:16
  #388 (permalink)  
 
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Please don't take offence at this but I find it very hard to believe that you are who you say you are. PPRuNe is of course an anonymous forum where anyone can pretend to be anyone else. I'm not saying that you are not the Captain of the crashed BA 777 at LHR but we have no way of knowing either way and this forum does attract some strange people. You have only just registered on PPRuNe with a user name relating to that incident and it seems very unlikely to me that the true Captain of that crashed aircraft would just pop up on PPRuNe after all this time in this way.
I disagree.I would imagine this is exactly the time that he would chose to say something.

Speculation can be distasteful if it is based on ignorance and makes an unfair assumption about a crew's performance.Providing it remains objective and draws no conclusion about the crew's performance,speculation is actually a wonderful tool that "tin-kickers" begin every investigation with.They just do it in private.Start with the plausible,slowly fine-tune it to the probable until the evidence finally gives you the undeniable.
We have been a bit lazy in describing this as a stall.Technically,the aircraft didnt quite stall.It was about to stall when it hit the ground.The "turbulence" the survivors spoke of was the stall buffet.
Belgique's last post restored some respect to the notion that speculation has merit.In it,he points to the "insidious" nature of speed bleed-off if the pilots attention lapses during an approach with AT off.Call-outs by both pilots throughout the approach are designed to ensure that stable approach parameters are never compromised in this way.His post also describes the unfortunate mix of full back trim,low speed and full thrust that can ensue when the pilot finally realizes the error of his ways.His causation para talks of the dangers of automation complacency and explains neatly how such a situation can develop.Not once does he tie it to yesterday's crash.It is simply offered as a topic for discussion that may or may not be central to yesterday's tragedy.
None of us know what happened yesterday.How did they get behind the drag curve so badly?Was it mechanical?Bird strike?Wake vortices?Was the wrong gross weight entered in the FMC?Were they victims of automation complacency coupled with incorrrect stall recovery?Is stall recovery with ground contact imminent part of our 6 monthly check?If not,why not?People seem to have ruled out weather and fuel and I think this is just common-sense.Professional pilots dont normally fly about with no fuel without saying something and the reported weather was benign.
Provided we remain rational and objective,speculation need not be a bad thing.
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Old 26th Feb 2009, 13:16
  #389 (permalink)  
 
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Dani -
Ah, and DC-ATE, my favorite enemy, is also here! FBW aircraft are not stallable. ... Remember Habsheim.
And a good day to you, Sir!

I will rush right out and buy one after reading that!

As to Habsheim. I do not put much faith in anything that comes out of that investigation for the following reasons:

Air France Flight 296 @ Mulhouse-Habsheim Airport -

The cause of the accident is disputed, as many irregularities were later revealed by the accident investigation.

Third-party investigations into the crash dispute the official findings.[2] Captain Asseline asserted the altimeter read 100 feet (30 m) despite video evidence that the plane was as low as 30 feet (10 m). He also reported that the engines didn't respond to his throttle input as he attempted to increase power. The month prior to the accident, Airbus posted two Operational Engineering Bulletins indicating anomalous behaviour noted in the A320 aircraft. These bulletins were received by Air France but not sent out to pilots until after the accident.

However, the recorders were taken by the civil aviation authorities and held for 10 days until they were finally confiscated. When the recorders were returned, they had been physically opened and the magnetic tape had been tampered with. It could not even be verified that they were the original recorders. The four seconds of recording immediately prior to the crash were missing. In view of this, a judicial report alleged that the aircraft's flight recorders could have been tampered with shortly after the crash.
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Old 26th Feb 2009, 13:19
  #390 (permalink)  
 
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ogel
I think they would just be concentrating on trying to maintain enough airspeed to keep flying (not stalling ,which even at 50ft would not be a good idea) whilst avoiding anything big and solid immediately in their flight path if the aircraft energy allowed them. Finally there is not so much difference between stalling speed and say a buffer of 15-20kts (to ensure control) in terms of the "landing roll", a bigger issue is the potential for an unchecked rapid pitch down of the nose if you do stall, which may have been the killer here for the guys in the front. Given the location of the horizontal tailplane after the accident, it is obvious that from the initial impact no pitch control remained of course.
Don't think no matter how cool headed the Capt he would be planning as you suggested, with or without power or sufficient airspeed I think he would merely be trying to make as soft as possible the off airport landing to try & save his own & everyone elses neck. Simple as that.

Last edited by captplaystation; 26th Feb 2009 at 13:31.
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Old 26th Feb 2009, 13:20
  #391 (permalink)  
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I would just like to add that after listening to the ATC files at the time of the crash the Dutch controllers seem a very professional group, kudos to them in what must be very demanding circumstances.

Could some kind soul point me in the direction of these files ??

Thanks

http://archive-server.liveatc.net/eh...2009-0900Z.mp3
http://archive-server.liveatc.net/eh...2009-0930Z.mp3

Edited: Posted links to wrong times

Last edited by Ber Nooly; 26th Feb 2009 at 14:38.
 
Old 26th Feb 2009, 13:21
  #392 (permalink)  
 
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A/T Disconnect

You will hear a clicking sound as the A/T arm switch on the MCP goes from ARM to OFF and a red flashing A/T discrete light in front of both pilots.
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Old 26th Feb 2009, 13:36
  #393 (permalink)  
 
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The wreckage being all relatively 'together' and no
skid visible behind, would indicate that the aircraft
stalled and dropped like a stone - not the same
outcome as the BA triple seven at Heathrow -
unfortunately.

MM
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Old 26th Feb 2009, 13:38
  #394 (permalink)  
 
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Why Winglets departed

For those of you wondering why the winglets departed the aircraft take a look at this video

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Old 26th Feb 2009, 13:45
  #395 (permalink)  
 
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You will hear a clicking sound as the A/T arm switch on the MCP goes from ARM to OFF and a red flashing A/T discrete light in front of both pilots.
Really? I'd have thought the 737-800 would be like the 747-400, in which case an autothrottle disconnect will set off a warning beeper, and give an EICAS AUTOTHROTTLE caution message. The autothrottle switch on the MCP will just sit where it was...in ARM.
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Old 26th Feb 2009, 13:46
  #396 (permalink)  
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AT Disconnect

Thanks for the update on the 737 AT disconnect warning sequence. Sounds like it would be pretty hard to miss it but not impossible I guess. A red visual warning is fairly insistent. I must admit I have missed aural warnings when they are not repeated.
 
Old 26th Feb 2009, 14:01
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are we all thinking a pilot would get slow?

when you throw in the Buffalo, USA crash of the Q400 and all the talk about the crew letting the plane get slow and stall...and then people suggest the same thing might have happened in Amsterdam?

Something isn't making sense. Air speed on the approach is such a vital component of the instrument scan...

I do wonder if there is a computer glitch somewhere which might mislead the pilots with the display of airspeed?

And those of you who think the old ''steam powered '' gauges were bad...I'm wondering if we embraced these new efis types too quickly.
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Old 26th Feb 2009, 14:06
  #398 (permalink)  
 
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Didn't the 737 have problems with stab trim motor run-aways
years ago? Or am I getting confused (again!) with something else?
There were so many reported incidents that the aircraft had a "Nose
-up" attitude just prior to crashing, I wondered if that could be a cause?
It's a very sad event.
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Old 26th Feb 2009, 14:12
  #399 (permalink)  
 
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Autothrottle Retard

In 1986 I was involved with a situation at a small airline with 747-200 who had a rash of autothrottle retards at about 250 feet on approach. Turns out the radio altimeters were spiking down to 0 feet at that point, causing the A/T retard. Pilots reported it was subtle enough that it could have been overlooked long enough to cause grief.

GB
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Old 26th Feb 2009, 14:20
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graybeard...you do have an interesting thought there.

now I know the Airbus 320 series doesn't have throttles that move automatically, but I thought the Boeings all did (my prehistoric 737 did).

We were required to have our hand on or about the throttles to feel them move during approach to make sure things were going correctly.
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