‘Altimeter caused crash’

Dutch investigation points to faulty device in Turkish Airlines tragedy

The head of the Dutch Safety Authority, Pieter van Vollenhoven, listens during a press conference in The Hague, Netherlands, yesterday. Investigators say a faulty altimeter played a crucial role in a Turkish Airlines crash that killed nine people in the Netherlands. The plane was landing on automatic pilot and the problem with the altimeter led to the loss of air speed before the crash just 1 kilometer short of the runway at Amsterdam’s Schiphol Airport on February 25.

By Toby Sterling -- The Associated Press

AMSTERDAM – A false reading from a faulty altimeter caused the autopilot system to sharply slow a Turkish Airlines jet far short of the runway last month, sending it plunging into a muddy field and killing nine people, Dutch investigators said yesterday.

Chief investigator Pieter van Vollenhoven said the Boeing 737-800’s flight recorders showed false readings from the altimeter on two flights before the February 25 crash a kilometer (less than a mile) short of the runway at Amsterdam’s Schiphol Airport. He did not say whether pilots had noticed the previous incorrect readings.

The Dutch Safety Authority said it had issued a warning to Boeing as a result of its investigation, asking the company to alert customers that when altimeters are not functioning properly “the automatic pilot and the gas system coupled to them may not be used for approach and landing,” van Vollenhoven said.

Boeing said it was reminding all operators of its 737s to carefully monitor primary flight instruments during critical phases, adding that it was carefully monitoring the fleet.

The deputy chairman of Turkey’s Pilots’ Association, Ahmet Izgi, told Turkey’s NTV news channel that the preliminary Dutch findings were “not satisfactory” and said it would be odd for the pilots to not react to a false altimeter reading in time to save the plane.

Van Vollenhoven said the plane carrying 135 passengers was being landed on autopilot, a situation he called not unusual. He said that the pilots had been unable to see the runway at the time the plane began its descent due to weather conditions – cloudy with light rain.

At 1,950 feet (around 700 meters) the airplane’s left altimeter suddenly and mistakenly registered an altitude of 8 feet (about 2 meters) below sea level and passed the reading on to the automatic control system, van Vollenhoven said.

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 but didn’t consider it a problem and didn’t react, van Vollenhoven said. But the autopilot reduced gas to the engines and the plane lost speed, decelerating until, at a height of 450 feet (150 meters), it was about to stall. Warning systems alerted the pilots.

“It appears then that the pilots immediately gave gas, full gas; however it was too late to recover,” van Vollenhoven told reporters. He said it would be for courts to apportion blame.

The plane fell into a freshly plowed field, striking the ground tail first and breaking into three pieces.

Eyewitnesses said it seemed to fall from the sky.

Passengers who survived had noticed the pilot gunning the engines at the last minute. Some didn’t realize the landing had gone wrong until other passengers began opening emergency doors.

Those killed in the crash included five Turks and four Americans. Turkish Airlines said the dead included the three pilots.

It described the captain, Hasan Tahsin Arisan, as an experienced pilot and air force veteran.

The company has said it will pay compensation to victims and survivors.

The American dead included three Boeing employees on a business trip unrelated to the flight.

As of yesterday, 28 survivors were still hospitalized.

The investigation is expected to last until the end of the year. Van Vollenhoven said that from now on “the technical investigation will be directed at the functioning of the automatic pilot, the automatic gas control system, and their coupling to the radio altimeter.”

The Turkish Pilots’ Association had earlier suggested the crash was due to “wake turbulence” from a large plane that had landed at Schiphol Airport two minutes earlier.