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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 5th Mar 2009, 02:58
  #1261 (permalink)  
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1. For GPWS systems that receive data from only one radio altimeter, see MMEL Item 34-26 for GPWS inoperative limitations if the number 1 radio altimeter is inoperative.
2. Insure that weather minimums or operating procedures are not dependent upon its use.
3. With radio altimeter(s) inoperative, do not use the associated autopilot or autothrottle for approach and landing
This is what the MEL says.Even if this aircraft didnt have an open RA defect that affected their dispatch,it had a history of unreliable indications,and so the MEL should have been consulted.The information would have been invaluable and reminded the Captain of the precautions for continuing an approach without RA#1...ie.use manual thrust,AP B or manual,GPWS modes rely solely on RA#1 data if no software update(no "glideslope" warning as RA#1 must be between 30' and 1000' for mode 5 to be active)
Consulting the MEL is an art in itself.If you can find the relevant item within 45 seconds,you're pretty good.M and O sections must be read and understood by all crew members.

I hope they dont go after Boeing on this one.Boeing shouldnt really have to release a statement reminding crews of the importance of monitoring their flight instruments.The culprits here are those airline training departments that place emphasis on autoflight of their aircraft and neglect basic stick and rudder skills.The same airlines that confuse CRM with democracy.The same airlines that teach a nauseating preoccupation with SOP at the expense of airmanship and common sense.
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Old 5th Mar 2009, 03:05
  #1262 (permalink)  
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Airmanship 101

Very sad state of affairs when a relatively simple failure of a single system leads to an outcome like this.

Also remember that the EFIS on the NG provides an Airspeed trend arrow showing where your speed should be in approximately 10 seconds. They had 100!!!

Windshear training (I know it is not a factor in this case) which all pilots flying this type of aircraft are provided, covers the "unusual thrust lever position on approach" scenario.

My company S.O.P's mandate a hand on the thrust levers below 3000' AGL to further enhance feedback from the Autoflight system. Remember that Boeing's philosophy is to provide a tactile feedback with Autothrust where Airbus does not.

I know that things can get busy....I've been there myself...but I still find it hard to understand how this was allowed to happen. Aviate, Navigate and Communicate as has been mentioned in many posts.
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Old 5th Mar 2009, 04:06
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'we were distracted..' appears to be a common theme in a large number of incidents/accidents that people have walked away from in the past.

will be interesting to see exactly what,if anything, the crew was so preoccupied with in this case.
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Old 5th Mar 2009, 04:38
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Rananim thanks for the MEL info.

I suspect this doesn't let Boeing off the hook for bad design. But, given preliminary evidence that previous problems with RA#1 came from the FDR and not from aircraft maintenance records, I expect this puts Turkish and perhaps the other crews involved on the hook for their maintenance and dispatch procedures. To say nothing of training and basic airmanship standards.
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Old 5th Mar 2009, 05:34
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I accept that there does seem to have been a comprehensive failure on the flightdeck to monitor the approach.

My interest is in the automation. Specifically, it does seem that due to the erroneous output from RAD ALT1 to the AP or A/T (automation) seems to have adjusted the aircraft power/configuration to one that if left unchecked would have an undesired outcome. It has always been my understanding that transport aircraft were designed around the principle that a single point of failure should not lead to the loss of an aircraft. Unless more comes to light, I'll be very interested in the recommendations/changes that transpire from this.

I've not seen it reported yet that the RAD ALT flagged as failed. If it didn't would a computer cross check of the two RAD ALT sources have given any indication to the crew?

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Old 5th Mar 2009, 05:38
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rubik101 -

One of the two flight attendants seated directly behind the cockpit was killed. Another FA (location unknown) lost a leg. The three Boeing employees that died where seated in first class. I've not seen any more information on the location of the two other deaths beyond that they were passengers. Given that, I'm inclined to assume that location was more of a factor than the restraint systems.
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Old 5th Mar 2009, 05:44
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It might be worth to consider why the crew used AP connected to RA2. They might be have been aware that RA1 was giving erroneous readings? If the answer is yes, than the subsequent question is: did they knew the A/T is always reading from RA1?
The above might answer why they did not react to erroneous reading of RA1
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Old 5th Mar 2009, 06:17
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On the 737 you usually use the autopilot/flight director system of the pilot flying. In this case this was the first officer in training and therefore it was normal procedure to use autopilot B.

So far i have not seen any indication if the crew was aware of the RA problems on RA1 or not.

And please guys, try at least to read the available information. The "faulty" (more correct: erronous reading) instrument in question was the RA which has nothing to do with the pitot-static system.
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Old 5th Mar 2009, 06:23
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I would not be surprised if the crew thought that since they were using AP B then the AT system would also read from RA on that side and they had no issues due to the captain's side RA malfunction. It's clear that they were very surprised at the low energy state of the aircraft once they found themselves in that situation. I also believe they were complacent to a long engines idle period during descent as it was mentioned in the briefing that they were in a relatively high energy state to begin with, so long engines idle periods were expected.
Of course this does not excuse the lack of airspeed awareness.
For obvious reasons, we will never know what they thought.

Wouldn't it be nice to have an "FDR" for the pilots brain... on the other hand, could be a lot of garbage data there
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Old 5th Mar 2009, 06:27
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Capt In Command When Stick Shaker Alerts on Short Final

In an event such as this it would not be the first officer in command (when stick shaker goes off on late final), the commander would take command.

What is the SOP for your airlines out there?

I await the full report on what reaction to the stick shaker was taken by the crew and when.

I hope the investigation assists in this never happening again.
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Old 5th Mar 2009, 06:30
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Message from Boeing to all B737 operators

Reference /A/ provides Boeing's previous fleet communication on the subject
event. The US NTSB, FAA, Boeing, the Turkish DGCA, the operator, the UK
AAIB, and the French BEA continue to actively support the Dutch Safety
Board's (DSB) investigation of this accident.

The DSB has released a statement on the progress of the investigation and
has approved the release of the following information.

While the complex investigation is just beginning, certain facts have
emerged from work completed thus far:

- To date, no evidence has been found of bird strike, engine or
airframe icing, wake turbulence or windshear.
- There was adequate fuel on board the airplane during the entire
- Both engines responded normally to throttle inputs during the entire
- The airplane responded normally to flight control inputs throughout
the flight.

The Digital Flight Data Recorder (DFDR) data indicates that the crew was
using autopilot B and the autothrottle for an ILS (Instrument Landing
System) approach to runway 18R at Amsterdam Schiphol airport. During the
approach, the right Low Range Radio Altimeter (LRRA) was providing accurate
data and the left LRRA was providing an erroneous reading of -7 to -8 feet.
When descending through approximately 2000 feet the autothrottle, which uses
the left radio altimeter data, transitioned to landing flare mode and
retarded the throttles to the idle stop. The throttles remained at the idle
stop for approximately 100 seconds during which time the airspeed decreased to approximately 40 knots below the selected approach speed

The two LRRA systems provide height above ground readings to several
aircraft systems including the instrument displays, autothrottle, autopilots
and configuration/ground proximity warning. If one LRRA provides erroneous
altitude readings, typical flight deck effects, which require flight crew
intervention whether or not accompanied by an LRRA fault flag, include:

- Large differences between displayed radio altitudes, including radio
altitude readings of -8 feet in flight.
- Inability to engage both autopilots in dual channel APP (Approach)
- Unexpected removal of the Flight Director Command Bars during
- Unexpected Configuration Warnings during approach, go-around and
initial climb after takeoff
- Premature FMA (Flight Mode Annunciation) indicating autothrottle
RETARD mode during approach phase with the airplane above 27 feet AGL. There
will also be corresponding throttle movement towards the idle stop.
Additionally, the FMA will continue to indicate RETARD after the throttles
have reached the idle stop

Boeing Recommended Action
- Boeing recommends operators inform flight crews of the above
investigation details and the DSB interim report when it is released. In
addition, crews should be reminded to carefully monitor primary flight
instruments (airspeed, attitude etc.) and the FMA for autoflight modes.
More information can be found in the Boeing 737 Flight Crew Training Manual
and Flight Crew Operations Manual.

Operators who experience any of the flight deck effects described above
should consult the troubleshooting instructions contained in the 737
Airplane Maintenance Manual. Further, 737-NG operators may wish to review
737NG-FTD-34-09001 which provides information specific for the 737-NG
installation. Initial investigations suggest that a similar sequence of
events and flight deck indications are theoretically possible on the
737-100/-200/-300/-400/-500. Consequently the above recommendations also
apply to earlier 737 models.

Operators will be notified if further action is recommended
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Old 5th Mar 2009, 06:33
  #1272 (permalink)  
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Dutch Safety Board: Malfunctioning altimeter caused THY 737 autopilot to decelerate

From ATW this morning:

A malfunctioning altimeter caused the autopilot system on the Turkish Airlines 737-800 that crashed last week on approach to Amsterdam to reduce power prematurely, and by the time the pilots reacted it was "too late to recover the flight," Dutch Safety Board Chairman Pieter van Vollenhoven said yesterday.

DSB's "initial findings" provided a strikingly clear explanation of the crash's likely cause less than a week after the Feb. 25 accident that killed nine (ATWOnline, Feb. 27) and led Boeing to issue a statement warning 737NG pilots to "carefully monitor primary flight instruments during critical phases of flight."

Vollenhoven explained that the aircraft's "automatic throttle system. . . received incorrect information because of a malfunction in the left radio altimeter." The cockpit voice and flight data recorders show that at 1,950 ft. the "left radio altimeter suddenly indicated a change in altitude, from 1,950 ft. to -8 ft., and passed this on to the automatic pilot. . .It seems that the automatic system, with its engines at reduced power, assumed it was in the final stages of the flight. As a result, the aircraft lost speed. Initially, the crew did not react to the issues at hand."

The crew, which included a captain, a first officer on a training flight and a third pilot in the cockpit, "were notified that the left radio altimeter was not working correctly" by a "landing gear must go down" warning signal, Vollenhoven said, adding that "provisional data indicates that this signal was not regarded [by the crew] to be a problem."

But the autopilot's deceleration "reduced [the 737-800] to minimum flying speed," setting off an alarm. The crew "immediately" attempted to apply full power, he said. "However, this was too late to recover the flight, the aircraft was too low and, consequently, the [aircraft] crashed 1 km. short of the runway."

DSB issued a warning to Boeing regarding 737-800 altimeters, advising the manufacturer to amend its manual to say that autopilot should be switched off if an altimeter malfunctions during flight. Boeing, which confirmed that three passengers who died in the accident were company employees, said it would "look closely" at the recommendation.

Vollenhoven noted that the aircraft's tail hit the ground first, followed by the undercarriage, and its forward speed "was about 175 km. per hr. upon impact. . .An aircraft of this weight should normally have a speed of 260 km. per hr. for landing." The three pilots died in the crash and 28 surviving passengers remain hospitalized.

"The board's investigation will now focus fully on the workings of the radio altimeters and the connection to the automatic throttle," Vollenhoven said. He conceded in a press conference that DSB was issuing highly detailed findings at an early stage in the investigation. "The reason to go public now. . .is to warn Boeing and all users of this plane type that vigilance is required with regards to the altimeter," he said.

Weather conditions at the time of the accident included a "low cloud base and. . .mist [that] probably meant that the [AMS runway] was not yet visible at the height at which the descent was commenced," which may have been a contributing factor, he said. Regarding the aircraft, there have been no "irregularities" found except for the altimeter malfunction, he said.
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Old 5th Mar 2009, 06:43
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Stick Shaker Question Answered

"But the autopilot's deceleration "reduced [the 737-800] to minimum flying speed," setting off an alarm. The crew "immediately" attempted to apply full power, he said. "However, this was too late to recover the flight, the aircraft was too low and, consequently, the [aircraft] crashed 1 km. short of the runway."

That answer my question about how quickly the crew reacted to the stick shaker - if that was the alarm they reacted to "immediately".

I cannot think what other warning it would have been?
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Old 5th Mar 2009, 07:17
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Forgive me for the question coming up:
None of the three guys in the front office noticed a thrust recuction over a period of 40 ( four zero) seconds?
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Old 5th Mar 2009, 07:18
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This was not an automation accident, nor was it a technical/mechanical/design accident.

An aircraft with a fault so minor it isn't in the simulator training syllabus was permitted to stall on final approach by a professional, high-time airline captain.

The rest are details.

Situational Awareness accidents are human factors accidents which may or may not have technical components and factors.

A pilot is a pilot is a pilot. Nobody here who flies professionally can reasonably blame a Radio Altimeter fault for stalling an airliner on short final causing a fatal accident.

Last edited by PJ2; 5th Mar 2009 at 07:34.
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Old 5th Mar 2009, 07:22
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Had a personal rule (airlines procedures differ) auto pilot on auto throttle on. Auto pilot off autothrottle off. Less confusion allround. In addition, with underslung engines, auto throttle commanding thrust causes pitch up, the hand flying pilot may behind the system.
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Old 5th Mar 2009, 07:26
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Im not familiar with the Air Data Logic at Boeing 737. At Airbus, there should be some kind of ADR Disagree Warning, resulting in Manual Flight and Manual Thrust - but nevertheless a horrable scenario for the crew.
Manual flight and Manual thrust should not be "horrible" for any jet crew, regardless of type. If it is then there is something wrong with the training system. More and more jets are crashing because of pilot's inability to safely fly manually at the basic level.

Magenta lines and computers are all well and good but when it counts, you need to be able to competently cope with none of the goodies. And the more the system tries to hide behind automation to stop manipulation accidents, the worse the accident rate will become.
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Old 5th Mar 2009, 07:32
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Just a thought.


Thank you for the MEL information. Question remains if the faulty RA 1 was reported in the tech.log. The information that it failed twice before came from the data recorders.So there is a possibility the crew was unaware of the failure of RA 1.


Your interpertation on HF sounds very professional to me. Roger Green and James Reason would have been proud of you. My idea is that the Dutch AIIB will not release the CVR tapes as they adhere strickly to ICAO Annex 13

I was impressed by the press release by Mr.van Vollenhoven who gave us the factual information and findings from the preleminary investigation.

Good Flying!

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Old 5th Mar 2009, 07:46
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@FrequentSLF - I think you hit the nail on the head here

They might be have been aware that RA1 was giving erroneous readings?
Yes, I think they were aware of this.

did they knew the A/T is always reading from RA1?
No, I think they did not know about this and this points to either Boeing and/or training issue.
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Old 5th Mar 2009, 07:47
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Finally, some commonsense emerging on this thread.
As long as pilots, their managers and the manufacturer bang there fists on the table asking the obvious and trot out all the old acronyms, we won't learn a thing.
It did happen- and some more answers are needed, but this industry is notorious for directing blame (check this thread........!) and it will only get worse.
We still don't know whether a bigger distraction was in progress (incap..??)
It was also complexed by
1/ being a training mission
2/ 3 on the deck
Anyone with jet training background during Line Ops in high workload airspace knows the demands the above 2 items can place on the cockpit integrity.
Now, big deep breath, and stop huffing about SOP's, cultural issues et al. and Boeing boys and girls- you wouldn't be the first to admit you didn't realise with an erroneous LH RA, the A/T could transition to Retard in flight, with only A/P B selected!!
Thanks in advance for listening..
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