Altimeter fault and pilot errors caused crash
Source: Agencies |
May 7, 2010, Friday
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Print Edition
Print Edition
A COMMON malfunction with Boeing radio altimeters, compounded by several errors by pilots, led to last year's fatal crash by a Turkish Airlines plane as it dropped short of the runway at Amsterdam's airport, according to investigators' final report released yesterday.
Flight TK1951 - a Boeing 737 carrying 135 passengers and crew from Istanbul - crashed 1.5 kilometers from Schiphol Airport on February 25, 2009. The three pilots were among nine people killed.
The Dutch Safety Board investigation affirmed its initial findings that a faulty altimeter played a key role in the crash.
The altimeter registered the plane's altitude as being below sea level when it began its final descent from 2,610 meters, which in turn caused the plane's autopilot to reduce the throttle too soon.
The plane was on an unusually steep approach and should have been slowing anyway, which may have played a role in the pilots' initial failure to notice they had lost too much speed, the report said.
"If the altimeter in the Boeing hadn't been malfunctioning, the accident wouldn't have taken place," Safety Board chief Pieter van Vollenhoven told reporters.
He criticized Boeing, saying the manufacturer was aware that altimeter malfunctions are common, but until the crash it considered them a technical problem and not a safety threat.
Boeing said yesterday it has "undertaken a range of actions" to prevent such an accident recurring.
Those included increasing the accuracy of the altimeter's readings; making its malfunction less likely to hurt other flight systems, such as the autopilot; and training flight crews to be alert to malfunctions.
In the Dutch crash, the pilots failed to react until the plane's control column gave a "stick shake" - a warning it was about to stall.
Within one second, the first mate, who was flying the plane, pushed down the plane's nose and gave maximum acceleration.
But then the captain took the controls. "I have," he said, according to the cockpit voice recorder.
He kept the plane's nose down but it once again lost gas. Seven seconds later it crashed.
Those killed in the crash included five Turks and four Americans. The Americans included three Boeing employees.
Flight TK1951 - a Boeing 737 carrying 135 passengers and crew from Istanbul - crashed 1.5 kilometers from Schiphol Airport on February 25, 2009. The three pilots were among nine people killed.
The Dutch Safety Board investigation affirmed its initial findings that a faulty altimeter played a key role in the crash.
The altimeter registered the plane's altitude as being below sea level when it began its final descent from 2,610 meters, which in turn caused the plane's autopilot to reduce the throttle too soon.
The plane was on an unusually steep approach and should have been slowing anyway, which may have played a role in the pilots' initial failure to notice they had lost too much speed, the report said.
"If the altimeter in the Boeing hadn't been malfunctioning, the accident wouldn't have taken place," Safety Board chief Pieter van Vollenhoven told reporters.
He criticized Boeing, saying the manufacturer was aware that altimeter malfunctions are common, but until the crash it considered them a technical problem and not a safety threat.
Boeing said yesterday it has "undertaken a range of actions" to prevent such an accident recurring.
Those included increasing the accuracy of the altimeter's readings; making its malfunction less likely to hurt other flight systems, such as the autopilot; and training flight crews to be alert to malfunctions.
In the Dutch crash, the pilots failed to react until the plane's control column gave a "stick shake" - a warning it was about to stall.
Within one second, the first mate, who was flying the plane, pushed down the plane's nose and gave maximum acceleration.
But then the captain took the controls. "I have," he said, according to the cockpit voice recorder.
He kept the plane's nose down but it once again lost gas. Seven seconds later it crashed.
Those killed in the crash included five Turks and four Americans. The Americans included three Boeing employees.
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