Recent crash in Netherlands, focusses on altimeter

[michal 44]

- SHOULD the crew have noticed the fatal decrease in airspeed according to 'procedures' ? (I.o.w.: do procedures require them to monitor airspeed in an automated landing? And how often ? )

You bet they SHOULD. It is part of basic airmanship skills that at least one pilot (if there are 2) constantly performs instrument scan. Every pilot learns it during his/her IFR training and then airline crews get additional training called Crew Resource Management that teaches them how to divide responsibilities between two pilots. There is simply no excuse for BOTH pilots to have their attention diverted away for so long from monitoring such basic performance numbers like speed, altitude and engine power. It reminds me of two other famous crashes with many fatalities when crews forgot to monitor their aircraft - the really famous Everglades crash of L-1011 and the DC8 crash in Portland that ran out of fuel while crew wrestled with the nose gear not being fully extended.

[scott967 62]

From the preliminary investigation it appears that the A/P was engaged in CMD B, which would take its alt ref from the right (correct) RALT, and "autoland" was not a factor. The pilots were flying a coupled ILS approach. The A/T takes its alt ref from the left RALT, which was providing faulty output. It wasn't stated, but it seems as though the left RALT did not flag a "fail". It looks like the A/T will command a retard when the RALT is 27 ft regardless of A/P function. scott s..

[fsx_missionguy 0]

Like:- SHOULD the crew have noticed the fatal decrease in airspeed according to 'procedures' ? (I.o.w.: do procedures require them to monitor airspeed in an automated landing? And how often ? )- And if so, WHY didn't they ? Or, if they did notice it, why didn't they react earlier ? - According to the black boxes, this Altmeter problem happened already twice in the previous 10 flights. But the statement doesn't clarify whether this was actually noticed by the other crews or maintenance personel, and if so, what their reaction has been or if/what was done about it.

Rob,As always, all excellent insights. Thanks for the info. I've not heard audio of this guy being cleared final or for landing, and I've searched for it (I just assume I can't find it, since it would be highly unusual and the Tower at Schiphol is highly trained and respected.)I'm amazed at the quality of the investigations conducted by the NTSB, which has a 4-man advisory team in on the investigation. They are incredibly thorough, and will leave no stone unturned. My initial feeling, just looking at the pictures, was that it was most likley wind shear, probably caused by the preceding aircraft's wake turbulence. However, knowing that there was a known faulty equipment of such import, one naturally turns their eye to the indifference factor.Cultural sensitivities will also be in play as this unfolds, I suspect. The Turks are investing a lot of face in the "hero" storyline (whether that be for cultural or financial reasons, probably both).

[michal 44]

From the preliminary investigation it appears that the A/P was engaged in CMD B, which would take its alt ref from the right (correct) RALT, and "autoland" was not a factor. The pilots were flying a coupled ILS approach. The A/T takes its alt ref from the left RALT, which was providing faulty output. It wasn't stated, but it seems as though the left RALT did not flag a "fail". It looks like the A/T will command a retard when the RALT is 27 ft regardless of A/P function.

This is really some solid info. Thanks Scott.

Cultural sensitivities will also be in play as this unfolds, I suspect. The Turks are investing a lot of face in the "hero" storyline

You bet. When a 737 crashed years ago in eastern Turkey during snowy weather (captain flew "illegal" approach, ignored warnings and hit the mountain) and when the final NTSB report came out blaming the crew Turks did not accept it and called pilot a "martyr". By the same token Egyptians never accepted similar reports blaming their pilots for Flash Air and EgyptAir crashes and instead blamed unspecified equipment failures. Certain cultures have very hard time accepting any blame. I think one Muslim cleric even hinted that a Muslim pilot can't make a mistake.

[rcbarend 37]

This is really some solid info. Thanks Scott.You bet. When a 737 crashed years ago in eastern Turkey during snowy weather (captain flew "illegal" approach, ignored warnings and hit the mountain) and when the final NTSB report came out blaming the crew Turks did not accept it and called pilot a "martyr". By the same token Egyptians never accepted similar reports blaming their pilots for Flash Air and EgyptAir crashes and instead blamed unspecified equipment failures. Certain cultures have very hard time accepting any blame. I think one Muslim cleric even hinted that a Muslim pilot can't make a mistake.

Please, let us take care that this thread doesn't end up in a debate about "countries" and "cultures".Because (but now I'm getting very philysofical), what are "facts" ??To give you one example (and I should blame myself for that ):Fact is (and you have to take my word on that) I don't speak the Turkish language. Like most of you probably don't as well.So if I state "Like, in Turkey, the crew have been presented in the press as "heroes", and I call that a "fact", I'm not correct.Because I assume that what the Dutch press reports about Turkish press on this, is actually correct. But is it ??Our main problem, even in this day-and-age, is that if we read/hear/see things in the media presented as a "fact", we are inclined to assume it IS a "fact".But if history teaches us one thing, presented "facts" in the media aren't always "facts" at all (everyone can fill in his own examples !) Heck, even the "fact" that the left Altmeter was faulty is only a "fact" to me, because I cannot imagine that this Investigation committee could be wrong (or even worse: would lie) about that.Just to put things into perspective :-)Rob

[michal 44]

Fact is (and you have to take my word on that) I don't speak the Turkish language.

Neither do I. And I have never been to Australia and frankly I am not sure if I can believe media/books that this continent exists. I never touched or surveyed it to verify its true geographic span. And I wasn't on the Moon when Armstrong is alleged to make his first step - so can't really trust it either. Just putting things in perspective ;)

[onurksn 1]

Very interesting posts so far. However, a few things must be clarified.First of all, the media in Turkey is going to be extremely harsh on Turkish Airlines. That has already started. The reason these pilots are presented as heros is because there is a major highway and buildings close to the crash site. Whether the crew crashed there intentionally or not is not known at this time. Personnally, I give little credit to this but you never know. My opinion is that that it was of pure luck. Unfortunately all of the 3 pilots died, they would have helped with the investigation.I would also like to point out that it is totally useless and incorrect to refer to "cultural issues" for the simple reason that the majority of the members here probably know absolutely nothing about Turkey or the Turkish way of dealing with these types of tragedies. Please do not compare Turkey to other countries either. Here the population is extremely critical towards Turkish Airlines when such incidents occur. Moreover, I wouldn't be surprised if many Turks prefered to fly with other companies for a while. Oh, and for the record, in Turkey, pilots who lose their lives are called martyrs for the simple fact that an unwritten code says state employees killed in the line of duty die as a martyr. As Rob said, the best way to debate on this is by sticking to the facts. A poster also mentioned that he couldn't find the ATC recording that corresponds to the landing clearance. You can find it here, http://www.liveatc.net It's right there on the top of the home page.What intrigues me most and the most of you judging by your posts is the lack of reaction from the crew. I certainly hope this will be clarified in future reports. It is hard to believe that the 3 of them just sat there while the aircraft just stalled itself...

[fsx_missionguy 0]

A poster also mentioned that he couldn't find the ATC recording that corresponds to the landing clearance. You can find it here, http://www.liveatc.net It's right there on the top of the home page.

Yes, I have listened to this recording. I do not hear a landing clearance. Perhaps it is in there, but I cannot discern it. There are some communications at the end which are so garbled as to make them incomprehensible to me. Does anyone know if a transcript of the public tower communications has been released in Holland?

[onurksn 1]

Yes, I have listened to this recording. I do not hear a landing clearance. Perhaps it is in there, but I cannot discern it. There are some communications at the end which are so garbled as to make them incomprehensible to me. Does anyone know if a transcript of the public tower communications has been released in Holland?

Yeah, you're right, sorry. I forgot about it, this one is actually approach clearance and hand off to tower. Oddly enough the tower recordings aren't released. Maybe they were enclosed for investigation.I don't think the communications with tower are available or surely someone would have noticed them by now. If there aren't any legal issues, hopefully they should come out in the future.

[rcbarend 37]

Yeah, you're right, sorry. I forgot about it, this one is actually approach clearance and hand off to tower. Oddly enough the tower recordings aren't released. Maybe they were enclosed for investigation.I don't think the communications with tower are available or surely someone would have noticed them by now. If there aren't any legal issues, hopefully they should come out in the future.

As said, the main reason why the investigation committee felt they had to disclose what they did at this moment, is because it can happen at any time again under simular circumstances.For the rest: it must be frustrating for everybody involved, but I think many questions will remain unanswered for a long time untill everything leading/related to this crash is cleared up. If even possible.Hence, I think much additional info (even if allready known), will remain "under the hood" for the time being.Regards, Rob

[rcbarend 37]

Neither do I. And I have never been to Australia and frankly I am not sure if I can believe media/books that this continent exists. I never touched or surveyed it to verify its true geographic span. And I wasn't on the Moon when Armstrong is alleged to make his first step - so can't really trust it either. Just putting things in perspective ;)

I DO admit that my example was a bit far-fetched ...LOL But I was just trying to make a point....Maybe a better example: just look at all the wars started in the last 100 years, where public opinion was manipulated by dictators/governments/media/etc presenting (in hind-sight) untrue "facts" to get support for starting these wars ?And about Neil Amstrong: why does that remind me of the movie "Appollo 11" ?? :-)Or of many websites like http://www.ufos-aliens.co.uk/cosmicapollo.htm (including heaps of simular "proof" on Wikipedia) ??But as far as I'm concerned, this does get a bit (??) off-topic, so no more from me on this :-)Regards, Rob

[KevinAu 441]

On a more serious note, maybe the radio altimeter was briefly confused by something which it wasn't programmed to deal with well; I don't imagine a 738's altimeter reads -8 as a matter of course.

Radio altimeter errors like that are not uncommon. If the RA had been written up previously and placed on MEL, an autoland would most likely have been prohibited by the MEL and the crew should not have even tried it. If the crew was somehow aware that the RA had been acting up, even if not officially placed on inoperative status, prudence should have gone against doing an autoland since any kind of lower than Cat I type of procedure requires RAs to be functioning properly. If the RA had been written up previously for these faults but returned to service by maintenance, investigation should focus on how and why that could have happened, since it ended up causing a crash.

[Antonio Lapa Gomes 0]

Read this article on the recent crash,http://news.yahoo.com/s/ap/20090304/ap_on_...nds_plane_crashRegards,John

Hi there,These are all quoted info concerning further investigations and are up to date;* Dutch Safety Safety Board: Safety Alert to Boeing: *** Recommend to review Fligth Manual B737: if radio altimeters are inop, autothrottles and autopilot must not be engaged; * 9 casualties; * 80 wounded, 28 still in hospital; * TK 1951 ETA 10.40 * No problems until last moment; * 3 qualified pilots in cockpit; * 1st officer flying the aircraft; * TK1951 received landing clearance, no delay in approach, direct approach; * Autopliot engaged during approach; * DFDR and CVR in good condition; * at 1950 ft, LH radio altimeter step change read out from 1950 ft to -8ft; * this faulty altitude was also reported to autothrottle; * CVR: crew saw altimeter discrepancy; * Crew did not see this discrepancy as problem, and lowered gear as gear warning was activated due to -8 ft radio alt; * As a result, autothrottle went into retard mode at 1950 ft rather than 50 ft due to faulty radio altimeter read out; * Aircraft slowed to stall speed; * Aircraft flight controls [autothrottles] thought airplane was above runway and went into "flare mode"; * At 450 ft stall warning /stick shaher activated; * power was increased immediately [!] [TOGA?], but power increase was too late to continue flight; * identical problem with LH radio altimeter happened twice before on this airplane in last eight flights; * that data was still on DFDR, as it had 25 hrs upto crach of recorded information; * Landing gear and engines broke off at impact as designed; * due to high power setting engines flew forward by 250m at impact separation; * investigation will now focus on radio altimeter, and relation/logic with autothrottle system; * runway was not [very well] visable to crew; * Dutch Safety Board will lead investigation; * Several other parties will support investigation [NTSB, Boeing, CFM internaional, Turkish authorities, ; * Good words for justice department, especially in isolating area around airplane; * Safety Board and Jutice Department back on same frequency; * Main objective of investigation is fact finding and improve safety; * Justice department will limited access to data, to protect "whistleblowers"; * radio altimeter fault is only technical fault found so far; * No indications of ATC faults; * No indications of [wake-]turbulence; * Too early to tell if crew made mistakes; * All members of invetsigation team are on same line of thinking * Not yet known where the 2 previous occurances of LH radio Alt happened * LH radio Alt not considered flight critical component, as function can be taken over manually by crew; * No conclusions on TK maintenance activities and procedures; * Aircraft will be recovered this week; Flight Global has some additional information, that was not read out during the press conference: * Crew actions under review; * engines responded normal to pilots' inputs; * unlcear LH radio alt faulure played significant role in the accident; * Boeing is expected to issue safety bulleting today; * aircraft entered approach fast and high; * after LH radio alt failure, thottles remained in idle for 100 seconds, all this time throttles were in retard mode, except for the last couple of seconds; * aircraft airpseed slowed 40kt below reference speed; * Aicraft descended through glideslope; * Captain was "coaching" First Officer in conducting the before-landing checklist; * at 400 ft stall warning and stick shaker activated; * first officer [pilot flying] immediately advanced throttles, however throttles were still in retard-mode; * Captain took control, First Officer then released throttle levers; * throttles automatically rolled back to idle, as they were still in retard-mode; * six seconds later throttles were advanced again; * too late to prevent contact with ground. Today <4 March 2009>, the Dutch Safety Board has issued a warning for airline manufacturer Boeing and presents its initial findings regarding the terrible accident involving the Boeing 737/800, Turkish Airlines flight. This accident claimed the lives on nine people (5 passengers and 4 crew) and 80 passengers were injured. Twenty eight of those injured are still hospitalised. The Boeing was en route from Istanbul to Schiphol (on Wednesday 25 February 2009) and was due to land at Schiphol at 10.40. The Boeing had had a regular flight and no problems had been experienced until just before the approach. There were three people in the cockpit, the captain was located on the front, left hand side. On the right hand side there was the first officer, for whom this was a training flight. (The first officer had all appropriate qualifications). There was also an extra first officer in the centre of the cockpit. The crew made contact with air traffic control (Amsterdam Radar) at 10.04 and was transferred to the tower at Schiphol - for the landing at 10.14. The tower then gave the Boeing permission to land on the Polderbaan 18R. The Polderbaan was approached according to fixed procedures, without any delay, and the Boeing was then given permission to decrease its altitude to 2000 feet (about 700 meters) and begin its descent to the Polderbaan. This descent takes place with the help of the automatic pilot, as is normal with Turkish Airlines (this method can be utilised by everybody, as can a manual landing). The voice recorder and the black box, both of which are in the hands of the Safety Board, show that an irregularity occurred during the descent, at 1950 feet. At a height of 1950 feet the left radio altimeter suddenly indicated a change in altitude from 1950 feet to - 8 feet - and passed this onto the automatic pilot. This change had a particular impact upon the automatic throttle system which provides more or less engine power. The radio altimeter normally measures the altitude of the plane above the ground very accurately and can start registering this from 2500 feet. As already mentioned, this radio altimeter is very significant for providing the appropriate power for an automatic landing. A Boeing is fitted with two radio altimeters, a left one and a right one. The black box has shown that this deviation only occurred in the left radio altimeter. The voice recorder has shown that the crew were notified that the left radio altimeter was not working correctly (via the warning signal landing gear must go down). Provisional data indicates that this signal was not regarded to be a problem. In practice, the plane responded to this sudden change as though it was at an altitude of just a few meters above the Polderbaan and engine power was reduced. 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. 2 As a result of the deceleration, the aircraft's speed was reduced to minimum flying speed (stalling situation) and warning signals (the steering column buzzes at an altitude of 150 metres) were given. The black box shows that full power was then applied immediately. However, this was too late to recover the flight, the aircraft was too low and, consequently, the Boeing crashed 1 kilometre short of the runway. The black box which can register 25 hours of flying time and which, in this case, covered 8 flights - showed that this problem had occurred twice previously in a similar situation, before landing. The aircraft initially hit the ground with its tail and then the undercarriage followed. The forward speed was about 175 km per hour upon impact. An aircraft of this weight should normally have a speed of 260 km per hour for landing. The aircraft came to a rapid halt (after about 150 m) as a result of the arable land being made up of boggy clay. The braking caused by the ground meant that the aircraft broke into two pieces; the tail broke off and the aircrafts hull ruptured at business class. The landing gear broke off, in accordance with its design. This also applied to the two engines. The full power and the sudden braking resulted in both engines continuing forwards for a further 250 meters. Most of the fatally wounded victims were located near the rupture, in business class, and the three crew members in the cockpit died as a result of the enormous braking forces, partially caused by the embedded nose-wheel and the forward movement of the aircraft. The section that remained most intact was situated around the wings. On board the plane there were 127 passengers and 7 crew, of whom 28 are still hospitalised. The Boards investigation will now focus fully on the workings of the radio altimeters and the connection to the automatic throttle (automatic steering system). Weather conditions, particularly visibility through the low cloud base and the mist, probably meant that the Polderbaan was not yet visible at the height at which the descent was commenced. The Safety Board board will be assisted in its investigation and its attempts to ensure lessons are learnt by the following organisations: the National Transportation Safety Board Bureau dEnquetes et dAnalyse (BEA) Aviation Accident Investigation Branche (AAIB) Directorate General of Civil Aviation (Turkse Rijksluchtvaartdienst, DGCA) Boeing Turkish Airlines The engine manufacturer, CFM 3 Inspectie Verkeer en Waterstaat (IVW) [Traffic and Waterways Inspectorate] Federal Aviation Agency (FAA, American Civil Aviation Authority) Vereniging van Nederlandse verkeersvliegers [Association of Dutch Commercial Pilots] Nederlandse vereniging voor cabinepersoneel [Dutch Association for Cabin Personnel] Internationally, both the ICAO and the EU stipulate that involved parties may take part in the Boards investigation (party system). The investigation itself, however, is supervised by and remains the Boards responsibility. The Board has also received a great deal of data from the Public Prosecutor for its investigation. Furthermore, there have been content-based contributions from a great many police organisations. The National Police Force, particularly all staff from the National Team of Forensic Investigation who are responsible for the forensic work at the location itself, the Aviation Police, who took all the aviation photographs, and the National Traffic Assistance team who helped the Board to measure the location of the accident. The Public Prosecutor took possession of the aircraft and, as a result, responsibility for guarding it lay entirely with them. Police officers from all over the country were drafted in for this purpose. We are extremely grateful for their outstanding and meticulous work and for guarding the aircraft. There was a misunderstanding regarding the use of the data from the cockpit voice recorder and the flight recorder (black box). It is established, in Dutch law, that the Public Prosecutor may only have access to this data if there is a question of abduction, terrorism, murder or manslaughter. In such a situation, the Safety Board is also legally obliged to hand over this data to the Public Prosecutor. In principle, there are two investigations being carried out into the accident. The judicial investigation. The search for punishable facts and the use of these to hold those responsible to account. The independent investigation. This investigation focuses fully on finding out what happened so that lessons can be learnt. There is always some tension between the two investigations. Within criminal law you may be silent. Nobody needs to contribute to his or her sentence. With the independent investigation, however, you want to ensure that everything is said. For this reason, the reports from the Board may not be used as evidence in lawsuits. From today onwards, the investigation by the Board will concentrate on two subjects: The technical investigation will focus on the role of the automatic pilot, the automatic throttle system and the connection to the radio altimeter. <This will take place with the same involved parties>. 4 Alongside the aforementioned technical investigation, the focus will also be on the management of the crisis. How was the disaster dealt with and what can be learnt from this. This investigation will also focus on the passenger list. The recovery of the wreckage will probably take place at the end of this week. The aircraft will be taken to another location for possible further investigation. The Board is of the opinion that extra attention is needed for the role of the radio altimeter when using the automatic pilot and the automatic throttle system. The Board has issued a warning for Boeing today requesting extra attention to a part of a manual for the Boeing 737, in which is stated that in case of malfunction of the radio altimeter(s), the automatic pilot and throttle system that are connected to this may not be used for approach and landing. The Board would like Boeing to consider an investigation into whether this procedure is also applicable during flight. With the exception of the malfunction of the left radio altimeter the investigators of the Dutch Safety Board have not yet found any irregularities. http://www.onderzoeksraad.nl/docs/rapporte..._4_maart_GB.pdfTurkish Airlines pilots ignored faulty altimeter before Amsterdam crash A faulty altimeter plus apparent inattention by the pilots caused the Turkish Boeing 737 to hit the ground a mile short of the Amsterdam runway, the accident investigation showed today. The investigators' preliminary report confirmed the widespread theory that the pilots let the automatic systems slow their plane to a dangerously low speed as it approached Schiphol airport. At 450ft, as the pilots scrambled to speed up, it stopped flying and flopped onto the ground, killing the all three flight deck crew and six others on board. What was revealed today was the event that led to the pilots' inattention. Normally, pilots are expected intensely to monitor the performance of the automated approach system when an airliner descends towards the runway, electronically locked onto the radio beam that defines the descending flight path, known as the glideslope. In the Turkish Boeing, however, the radio altimeter "told" the flight system that the plane was actually eight feet below the surface when it was still nearly 2,000 feet in the air. This caused the "autothrottle" to pull back the power to idle, as if the plane was touching down. According to conversation recorded between the plane's captain, first officer and an extra first officer on the flight, the pilots noticed the faulty altimeter earlier but did not consider it a problem and did not react, the chief accident investigator said. The co-pilot, or first officer, was at the controls for the landing, watched from behind by an instructing third pilot. With power almost non-existent, the automatic pilot attempted to keep the aircraft on the profile of the glide-slope and may have started "flaring", or pulling the nose up for landing. The plane then slowed to the edge of stalling speed while still relatively far from the ground. The emergency warning systems came into action, sounding an aural warning and shaking the control columns to alert the pilots to the impending stall. They applied maximum power, but, since it takes seconds for jet engines to react to power commands and make an airliner to accelerate it was too late for the Boeing to regain flying speed and recover from the stall. The plane hit the ground with engines under full power, struggling to climb back into the air. The pilots' awareness of their predicament was dimmed because low cloud and mist prevented them from seeing the runway below and ahead of them as they began their descent from 2,000ft. However, the pilots would normally have been expected to react immediately to the auto-throttle command to cut power, especially since they were aware that the radio altimeter was playing up. The radio altimeter is used in large aircraft as a supplement to the less accurate traditional barometric altimeters that take their reading from the pressure of the atmosphere. The instrument panel in front of the pilots would have been displaying their correct altitude, taken from the main altimeters, while the usually more accurate radio altimeter was feeding into the flight system. The description of the fatal final moments of the Turkish airliner contrasts with the accounts from Turkey and some passengers of "hero pilots" who managed to save a crippled aircraft from worse destruction. If confirmed, the failures by the pilots would make the Amsterdam at least the fourth in 13 months in which pilot error has caused an airliner to stall and crash. The others were at Madrid last August, off the French city of Perpignand in November and near Buffalo, New York, last month. The initial accident findings are certain to intensify debate in the flying world over the dangers of pilots losing their basic flying skills as a result of relying on the sophisticated electronics that control airliners through most of their flights.Cues should alert 737 pilots to altimeter fault: Boeing Boeing has highlighted to 737 operators the symptoms of a malfunctioning radio altimeter, after investigations into the Turkish Airlines approach crash at Amsterdam found evidence that a faulty altimeter prompted the autothrottle to reduce thrust. The airframer points out that such symptoms might warrant crew intervention and it is reiterating the importance of monitoring flight instruments. Boeing says the autothrottle uses data from the left-hand altimeter which, in the Turkish jet, suddenly switched to an incorrect reading while still at nearly 2,000ft. This reading apparently prompted the autothrottle to transition to landing-flare mode, retarding the thrust levers to the idle stop, where they remained for about 1min 40s, bleeding off the airspeed. The 737 lost altitude and the crew failed to recover the aircraft before it struck the ground. Boeing has pointed out that an erroneous radio altimeter reading - even without a direct fault flag - will typically generate a number of possible effects on the flight deck, requiring crew action. Apart from differences in the displayed radio altitudes, these effects include unexpected configuration warnings, premature annunciation of authrottle retard, removal of flight-director command bars, and movement of the throttle levers towards the idle position. "Crews should be reminded to carefully monitor primary flight instruments and the flight-mode annunciation for autoflight modes," says Boeing. It states that the Turkish aircraft and its engines responded properly to flight-control and throttle inputs, and adds that the investigation into the 25 February crash has produced no evidence of wake turbulence, windshear, icing, bird strike or fuel exhaustion. http://www.flightglobal.com/articles/2009/...ult-boeing.htmlBoeing issues immediate warning 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 flight. - Both engines responded normally to throttle inputs during the entire flight. - 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) mode - Unexpected removal of the Flight Director Command Bars during approach - 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.also this OpenATC url: http://www.openatc.com/THY1951/Regards ALG

[orchestra_nl 927]

Thank you for this info. Strange though that the autothrottle takes info from just one altimeter. I visited another forum where real world pilots meet and read that probably a lot of pilots are not aware that with single channel ILS the autothrottle will still retard to idle as it does on dual channel ILS. Seems that the Boeing manual is vague on this also.In some Turkish newspapers the pilots were declared heroes because they sacrificed themselves and "landed" the aicraft in an unpopulated field, avoiding casualties on the ground. The picture shows that in all probability, the pilots didn't (need to) change course since the field was in their direct path. They probably didn't have the time for it anyway. If they had had the time to look for an empty field and make an emergency landing they probably would have had time to prevent the accident in the first place.Allard.

[KevinAu 441]

Thank you for this info. Strange though that the autothrottle takes info from just one altimeter. I visited another forum where real world pilots meet and read that probably a lot of pilots are not aware that with single channel ILS the autothrottle will still retard to idle as it does on dual channel ILS. Seems that the Boeing manual is vague on this also.Allard.

I don't see why there should be anything strange about the AT receiving input from only one RA source. Even if it took input from both RAs, it would not keep you from either smashing the plane into the ground or stalling it from on high. If one RA is saying it is at 27' while the other is showing that it is at 150', how would the AT know which one to disregard? The only safe course of action is to go around and/or not attempt any kind of autoland with a questionable RA. The only reasonable way to incorporate information from a second RA into this process is for miscompare monitoring and if that trips, then it should warn the pilots that autoland is not available.