Turkish Airlines Crash Caused by Faulty Altimeter

According to BBC the Turkish Airlines crash at Amsterdam last week has been caused be a faulty altimeter.

Dutch Safety Board chairman said at a press conference today, that the plane was still on autopilot when the crash happened and problems with the altimeter led to a loss of speed. He also stated the plane had twice before reported problems with its altimeter.

Investigation has shown that the plane had been at an altitude of 1950ft (595m) when making its landing approach to Schiphol airport. Suddenly the left radio altimeter indicated a change in altitude – from 1950 feet to – 8 feet – and passed this onto the autopilot. This change had a particular impact upon the automatic throttle system which provides more or less engine power. Its systems believed the plane was already touching down due to the wrong (too low) reported altitude. The automatic throttle controlling the two engines was closed and they powered down. This led to the plane losing speed, and stalling.

Dutch Safety Board chairman Mr Van Vollenhoven said that a conversation recorded between the captain and two first officers in the cockpit showed they had noticed the faulty altimeter but did not consider it to be a problem. “The crew initially did not react to these events, but when the stall warning system sounded, they immediately applied full power. But the plane was too low at 150m. As a consequence the plane crashed 1km before the runway”. 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”.

The black box has shown that this altimeter problem had occurred twice previously in a similar situation, before landing.

The Dutch Safety 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.

Dutch Safety Board Investigation Report (PDF, English):

Full story at: http://news.bbc.co.uk/2/hi/europe/7923782.stm

As always, thanks to “prop-er”!