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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 6th Mar 2009, 13:06
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vonbag - how is Soesterberg? I recall some 'interesting' times there in mil days.

That's Boeing off the hook on that one, then. Now - does anyone have ANY news at all form the investigation of interest? CVR, more FDR?

six7 - you will see that the crew probably expected throttles well back for some time on the approach, so it may not have been such a clue as you suggest - and anyway - how do you know there were no 'hands' on - have I missed something?
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Old 6th Mar 2009, 13:34
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Shouldn't be a sudden change of 1958 feet in RA1 reading considered as malfunction?

I'm a non pilot, tech savvy curious Turkish guy. I read all the 78 pages so far and many other forums. I'll try to be objective yet forgive me if I'm wrong.

First of all I agree that the crew's initial mission is to fly the airplane by continuously checking altitude & speed. So so far it seems that pilots deserve some (it depends how much) part of the blame here. I also agree with both the cultural issues & the military crew members' seniority rank issues having prevented the safety pilot to intervene. Yet I also consider that pilots can't be all to blame. 100 seconds is a lot and without CVR we do not know what on earth happened there in the cockpit.

You pay zillions of dollars to Boeing for state of the art avionics masterpieces that you can rely. You expect the autopilot mechanism to be close to fail proof. Here I really can not understand the design of the 737ng flight computer system, if RA1 feeding the FCC B, why on earth the pilot commanding FCC B looks at RA2. There is supposedly a "sudden" change of 1958 feet (1950 to -8) in RA1 reading, how on earth Boeing engineers could not have foreseen that such a huge variation should deactivate auto pilot?

This is easy you do not have be engineer to figure this out. Suppose you are very punctual and carry two watches, one on your right hand and one on your left. You usually check the left one, let's say every hour. All of a sudden you realize that the left one has gone behind/forward like "5 hours" since the last time you checked. What would you do? Would you just think that 5 hours went by? You cross check the one on your right. You realize the left one is kaput and you keep checking the right one until you have the left one fixed.

If the RA1 reading variance was like 100/200/10/50 feet you would be right, no way a computer might have just by cross checking with the RA2 realized that RA1 was malfunctioning. Come on guys! It's a sudden change of 1958 feet. t0 you are at 1950 feet, t1 you are at -8. And the reading is so negative even below what should the 737 RA read on the ground. (-4) This is a major engineering and design scandal. Boeing is there to blame, not for a faulty RA, that can happen, but for a faulty flight computer safety system. Now Boeing claims that in case of malfunction of RA 1, FCC would consult RA 2. Yet I'm sure by Feb 11 alert they didn't know that a negative reading and a huge variance in altitude counted as a malfunction. On Feb 11, they focused on the faulty RA to be fixed and serviced, rather than focusing on what would a faulty RA cause at 737ng's state of the art avionics. They should have issued the recent detailed warning back then in Feb 11. Yet we all know that even highly skilled and experienced 737 avionics experts do not know for sure the protocole when & how FCC consult RA2 instead of RA1. A lot of pilots confessed her and there they didn't know FCC B was fed by RA1, while they were looking at RA2.

One other issue is that, as back as in September 2007, I read in local forums that THY 737 pilots were complaining about negative left RA readings. They were told and believed this to be harmless and explained with "yet another cell phone activated". Due to such a repetitive error, resolved with a stupid explication, crew may have ceased to report this "harmless error". That might be the reason the previous errors are there on the FDR, yet not on the airplane's maintenance log book. Here all THY 737 pilots, airlines maintenance and training & Boeing technical crew are to blame.

Yet this fault, initially reported at THY, dates back to 2007 and Boeing didn't figure out that it would interfere with flight safety processes on auto pilot, as this is the lead RA feeding the FCC. I'm sure many other airlines' 737's had the same (-8) reading issue, reported or not. Not fixing it is much worse than designing a faulty computer system. No design is fail proof. Microsoft does major mistakes, but they issue patches, try to fix things. Why Boeing didn't fix this earlier?

Having said all this. Can anyone clear me on the ATC's role in 100 seconds of crew paralysis. Shiphol ATC having a radar and ILS should have closely monitored the 737's approach on their screens, starting at around 2500 feet. They would know its altitude, speed and distance from the airport at any given time. Why on earth haven't they warned the crew? Why anybody doesn't talk about this? Or am I too wrong in assuming they should have.
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Old 6th Mar 2009, 13:43
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Having said all this. Can anyone clear me on the ATC's role in 100 seconds of crew paralysis. Shiphol ATC having a radar and ILS should have closely monitored the 737's approach on their screens, starting at around 2500 feet. They would know its altitude, speed and distance from the airport at any given time. Why on earth haven't they warned the crew? Why anybody doesn't talk about this? Or am I too wrong in assuming they should have.
ATCs prime role is to control rather than "fly the a/c". Even if Schipol had been equipped with Precision Approach Radar they probably wouldn't have noticed anything too untoward since, from the data we have available here, the a/c was on centreline and glideslope at least until stick shake. I guess the only slight clue might have been the lower groundspeed after 2,000 ft but by the time ATC had noticed it would have been (almost) all over.
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Old 6th Mar 2009, 13:48
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... and that gentlemen and ladies, was one of the most sensible and thoughtful posts on this entire thread, from one of PPRuNe's younger contributor's, not a pilot and not even a native English speaker.

Very well said, cargun !
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Old 6th Mar 2009, 13:53
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Last edited by Rainboe; 17th May 2009 at 21:55.
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Old 6th Mar 2009, 13:55
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Cargun

Having said all this. Can anyone clear me on the ATC's role in 100 seconds of crew paralysis. Shiphol ATC having a radar and ILS should have closely monitored the 737's approach on their screens, starting at around 2500 feet. They would know its altitude, speed and distance from the airport at any given time. Why on earth haven't they warned the crew? Why anybody doesn't talk about this? Or am I too wrong in assuming they should have.
It's been covered in this forum already. Tower don't have the knowledge, means or responsibility to evaluate approach speeds.
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Old 6th Mar 2009, 13:56
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cargun

Please get this straight - there was no problem with the autopilot. The system we are concerned with is the autothrottle which is separate. The misreading radalt sent a signal to the autothrottle to retard at an inappropriate time.
I repeat what I said on a previous post. Neither the autothrottle nor the radalt were important in what the crew were doing, namely a single autopilot approach to cat 1 minima. The only time the radalt is of vital importance is during a dual autopilot approach and autoland. Boeing have made it clear that, in that case, a malfunctioning radalt will disconnect the autopilot, thus telling you that you cannot continue with the cat3 approach -go around or continue with a manually flown or single autopilot cat1 approach. I also repeat that the autothrottle is not required for a cat3 approach
I suggest that Boeing do not regard either the radalt or autothrottle to be of sufficient importance as to have an endless system of fail safe devices attached to them - they do not have that much relevance to the safety of the aircraft. Maybe they will now reconsider but personally I do not see the point. It would be a pain if a simple thing like a faulty radalt stopped you using the autopilot.
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Old 6th Mar 2009, 14:03
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Short version:
Yes, the radio altimeter did not function properly, and played a role in the particular sequence of events that happened here.
However, from the evidence so far available, the crew's behavior was such that, when combined with any number of other minor faults, it would have had precipitated similar or worse catastrophic results.

I also find bewildering the number of self-professed technology experts who, when presented with a problem involving the unexpected interaction of three components (radio altimeter, autothrottle, autopilot), think the solution is to make the system more complex and further isolate the operator from reality.

A perfect "RADALT1 failure detection system" will not avoid future tragedy if pilots forget to fly the plane.

At least that's the case to my untrained eye.
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Old 6th Mar 2009, 14:05
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cargun - you have valid points on system design, but you have been misled by all the 'spam' on here.

Now Boeing claims that in case of malfunction of RA 1, FCC would consult RA 2.
A/P B does not 'look at' RA1 AS FAR AS THE PILOTS' TECH INFO IS CONCERNED. Also, as far as anyone knows, there is no feature for an automatic 'swap' of RA in the event of failure of one. The troops are out on that one and we may all learn something soon.

RA1 feeds AP 'A' AND the Autothrottle, and other things, but not A/P 'B'. If RA1 FAILS, you lose the a/throttle input and GPWS warnings and an input to the rudder control function - that is all. A/P 'B' stays fully serviceable and useable.

NOW, TALKING SINGLE CHANNEL APPROACH, A/P 'B': (as we understand at AMS)

The sole function of RA2 is to feed A/P 'B' with radio height to reduce the control inputs the A/P will make to track the landing beam as the a/c gets nearer to the runway. A/P 'B' takes no notice of RA1.

The sole function of RA1 is to feed info to the A/Throttle and provide GPWS info (and rudder). It is quite acceptable to operate with either u/s as long as the crew are aware of certain limitations, and in fact both u/s, while not 'allowable', would not constitute a major problem.

As to your overall points - I'm sure Boeing will be reviewing this now.

foresight - you are confusing cargun now -
The only time the radalt is of vital importance is during a dual autopilot approach and autoland.
- not true. Loss of a RAlt renders that A/P approach mode u/s - read the MEL!
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Old 6th Mar 2009, 14:08
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@fireflybob

I understand what you mean, they sure can not be fully accountable, yet I believe with some luck and proactive judgment, they might have saved the plane. The plane was on glideslope so ATC eyes didn't notice a visual anomaly. Yet speed should be a major parameter, as glideslope, altitude and distance to are. I think it's somehow displayed as a tag on the ILS screen on top of the aircraft symbol. I would expect from precision high-tech avionics and ATC software (I'm sure Schiphol has the latest and foremost) to alert the ATC staff regarding the low ground speed at least around 1000 feet. What about visual contact with the tower, what was the cloud base altitude at the time of the accident, anyone?

This is a "total" paralysis. A serendipity of bad judgment starting from Seattle, visiting Istanbul and sadly terminating at Amsterdam. I don't think an aircraft flies with just 3 people in the cockpit. From designers, to engineers, maintenance crew to training people, simulator developers to air traffic control crew everyone has its share of responsibility. It's easy to blame the crew, alone.
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Old 6th Mar 2009, 14:14
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BOAC

foresight - you are confusing cargun now -
Quote:
The only time the radalt is of vital importance is during a dual autopilot approach and autoland.
- not true. Loss of a RAlt renders that A/P u/s - read the MEL!
Hardly of vital importance.

I was trying to get across to a non pilot that the piece of equipment which seems to have started this whole sequence of events is of relatively minor importance.
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Old 6th Mar 2009, 14:17
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Power+Attitude=Performance

Remember the old adage:

Power+Attitude=Performance?

In this case, clearly there were distractions (I imagine having a jumpseater was one of them)- maybe the emergency checklist for the RadAlt failure (I don't fly Boeings so I don't know what would be carried out) was being read- or the failure consequences was being demonstrated to one or both the trainee pilots- and basically at this critical time the aircraft was not being flown by anyone.

From my recollections of the 737, the trim wheels move at a rather frightening speed and make a noise like nothing else I have heard. Surely, if the power setting had been overlooked, the nose would be raising to maintain the glideslope and the trim wheels would be winding back trying to keep the thing in trim. The consequence was the speed reduced to Vref-40 and the rest is history. I suspect with the amount of drag being produced at that low speed (plus a high nose attitude) the aircraft was doomed just as the Titanic was the moment the iceberg was struck.

Very sad, but why nobody noticed all the clues will have to be determined by the crash investigators. I am convinced the distraction of the third crew member will be the key to this disaster. Had the PF remembered the equation above or the old favourite Aviate Navigate Communicate, we would not be looking at a hull loss and the tragic loss of life that we can now see one mile from the Polderbaan.
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Old 6th Mar 2009, 14:25
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The response from all the different Turkish institutions, ranging from the airline involved, the Turkish pilot union , the Turkish media, plus individual participants on this forum is very worrying. It seems to be more important not to be blamed in any way for this tragedy, than learning any lessons. There are a number of very reputable investigation bureau’s involved, they will do their work with impartiality and in a year’s time issue their final report.

The stance of the Turkish authorities so far make me fear an outcome similar to the Egypt Air 990 (B767 crash of Nantucket). Whereby the Egyptians never signed off on the final report that the NTSB issued, because of all sorts of national sensitivities.

The fast majority of writers in this thread are just armchair quarterbacks, with too much time on their hands. For the professionals the lessons will soon brought to our attention. For the rest it is just speculation based on rumour, innuendo and a fantastic lack of knowledge by many.
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Old 6th Mar 2009, 14:26
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The missing link - the pilot

Rainboe

"What was missing that day?"

Possibly simple aviation.

An IR rating instructor once said to me that if you land/crash an aircraft short of the runway the chap from the CAA is likely to arrive at the scene of the site with a pilot error report arleady in his bag and that he would work backwards from that postion. Cynical perhaps!
 
Old 6th Mar 2009, 14:27
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Im not a Pilot, I say it before.

Because of that, I have the following Question:

In the case, Autopilot A and B were activated. At the moment, the Radio Altimeter of the Captain showed -8 Feet, both Autopilots would be disconnected.

The Autothrottle wouldn´t disconnected and changed to Mode Flare and Retard. In the case, both Autopilots were disconnected, would the Autothrottle change to Flare and Retard.
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Old 6th Mar 2009, 14:31
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foresight



This thread itself seems to be a battle of intellect between the "Gods of Glass" and old f **ts like myself..........and in it's way is quite illuminating (IMHO), on one hand we have the techies who want to analyse every single wiggly Amp, line of code or whatever, looking for a "reason" for the accident and then perhaps opportion some of the blame to Boeing, the Company Engineers, even ATC. On the other hand we have the "Aviate, Navigate, Communicate" lot who know that when you are out of speed and height you're out of ideas....

To paraphrase and alter words from somebody else, flying isn't terribly difficult but it's terribly unforgiving, so you'd better pay attention.
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Old 6th Mar 2009, 14:31
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Manuma - No - A/P 'A' only should disconnect. Yet again - A/Throttle has no FLARE function. It is all in here if you read. With no A/.P engaged, but A/T engaged, RETARD is functional.
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Old 6th Mar 2009, 14:38
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@ rainboe

I'm sorry but this is the kind of tech behavior that prevents us recovering faults, bugs, errors, mistakes. This is deep myopia, total submissiveness to an aviation company. This behavior is like radical religiousness. Yet Boeing is not God. The fact that their systems are highly technological and advanced doesn't mean that they wouldn't make fatal mistakes. In fact the higher the technology used the more complicated the code, processes etc... and are prone to deficiency. The systems are designed, coded, reviewed & manufactured by man. An engineer has months, years to solve a problem, unlike the crew with limited decision making time.

Sorry for the ATC question, that I simply asked to learn. Yet as you seem to be defending Boeing you shouldn't be concentrated on that and rather answer basic system design critics and system fault fixing issues I raised. I asked relevant questions, instead of categorically denying the inputs of a non pilot, non-tech newcomer you should go research and try to answer, so that we all learn.

PS: Sorry for my jargon I used autopilot in general referring to many parts of this complicated system, just to simplify things and try to see the big picture. In this forum you are so taken away with abbreviations and technicalities that you sometimes can not see things as basic and simple as an outsider.
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Old 6th Mar 2009, 14:42
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Thank you for your answer BOAC.

I heard, that both Autopilots would disconnect. Thank you for your Declaration.
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Old 6th Mar 2009, 14:45
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Perhaps time to draw breath and summarise?

From the PROPER reports so far:

Trainee F/O flying A/P B coupled ILS into AMS 18R. J/seat pax of unknown status. Typical short-changing on track miles at AMS by ATC possibly caught the pilots and cabin crew a bit on the hop and the approach had the hallmarks of being potentially unstable. At around 2000ft, somewhere around LOC intercept, RA1 malfunctioned and sent a 'RETARD' command to the A/throttle (?and a 'Too low gear' GWPS?). The A/T action appears to have gone un-noticed, as the throttles were presumably closed at this point anyway. The A/P flew a 'normal' ILS, but with idle power, the speed was reducing below normal. Again apparently un-noticed until below cloud when the stall warning triggered at Vref-40kts. A fumbled attempt at stall recovery, apparently leaving the A/T engaged, resulted in a failure to complete a recovery. The Training Captain is then thought to have applied full power but too late to prevent a disastrous impact.

I think that is about as accurate as we can be at this time. The CVR and FDR will give the clues as to what was going on in the cockpit.
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