* Faulty altimeter led to plane's reduced speed
* Air traffic control gave insufficient directions
* Boeing has since implemented altimeter measures
* Turkish Airlines disputes pilot error to blame
(Adds Boeing, Turkish Airlines comments)
By Aaron Gray-Block
AMSTERDAM, May 6 A faulty altimeter and pilot error led to the Turkish Airlines crash at Amsterdam last year, Dutch investigators said on Thursday, urging the industry to improve training and reporting of technical glitches.
Nine people were killed when flight TK 1951 from Istanbul crashed on approach to Schiphol Airport on Feb. 25, 2009. Investigators had earlier said a faulty altimeter had shut down the engine of the Boeing (BA.N) 737-800 before it crashed.
But the Dutch Safety Board said in its final report that a combination of the altimeter problems, bad reactions from the Turkish Airline (THYAO.IS) pilots, plus a loss of speed and insufficient air traffic control directions led to the crash.
The board said that due to the failing of the altimeter, the airliner automatically lost speed, dropping below the minimum velocity needed to avoid the risk of engines stalling.
The pilots failed to intervene either adequately or early enough at several crucial moments of the descent, said safety board director Pieter van Vollenhoven, who called for better international pilot training to deal with emergencies.
In response, Boeing said accidents rarely result from a single failure or action and added it has since taken several steps to prevent the same chain of events that led to the crash.
These include measures to reduce the likelihood of discrepant altimeters, make other systems more tolerant of erroneous readings and provide additional indicators to assist flight crews monitor altimeters and air speed.
Turkish Airlines disputed the safety board's finding that approach stabilisation played a role in the crash and that the crew could have saved the aircraft after a stall warning was received.
"Even though the crew promptly reacted, autothrottle kicked back unexpectedly. The second attempt by the crew, after disengaging the autothrottle, to advance thrust levers was succesful but too late," the airline said in a statement.
Safety board chief Van Vollenhoven said at a news conference that via "an exceptionally unfortunate combination of circumstances" the flight crew received insufficient directions from air traffic control on how to approach the runway.
The pilots were advised to conduct the approach via a frequently-used "short turn-in", but were not advised to also descend, masking the malfunctioning of the plane's autothrottle.
Van Vollenhoven added Boeing and many airlines were aware of problems with the radio altimeter system, but that this had been considered a technical rather than safety issue. Also, in most cases, pilots did not report problems with the altimeter system.
Dutch law office AKD Prinsen Van Wijmen (AKD) said last September survivors of the crash have agreed to its advice to ask Clifford Law Offices to start compensation proceedings in the United States against Boeing.
Frans Vreede at law firm AKD said he was most concerned by findings that an altimeter comparator was not installed in the plane to ensure the right-hand altimeter, which was operating correctly, overrode the left-hand altimeter or alerted pilots.
Passengers suffered broken backs and shattered legs or psychological trauma, Vreede said. The case is still pending.
Evert van Zwol, chairman of the Dutch pilots association, welcomed recommendations for improved training, saying that training should be repeated annually or once every two years. (Additional reporting by Ayla Jean Yackley in Istanbul; Editing by Mark Heinrich)