Pilot suicide a taboo topic in past crash probes

As police investigate the two pilots of a Malaysian passenger jet that disappeared more than a week ago, a possibility they must consider, however remote and improbable, is that one of them committed suicide.
While such incidents have happened before, the topic remains almost taboo, with investigators and officials reluctant to conclude that a pilot purposely crashed a plane in order to commit suicide even when the evidence appears compelling.
A dozen years ago, US investigators filed a final report into the 1999 crash of EgyptAir Flight 990, which plunged into the Atlantic Ocean near the Massachusetts island of Nantucket, killing all 217 aboard.

They concluded that when co-pilot Gameel El-Batouty found himself alone on the flight deck, he switched off the auto-pilot, pointed the plane downward, and calmly repeated the phrase "I rely on God" over and over, 11 times in total.
Yet while the National Transportation Safety Board concluded that the co-pilot's actions caused the crash, they didn't use the word "suicide" in the main findings of their 160-page report, instead saying the reason for his actions "was not determined."
Egyptian officials, meanwhile, rejected the notion of suicide altogether, insisting instead there was some mechanical reason for the crash.

There was also disagreement over the cause of the crash of SilkAir Flight 185, which plunged into a river in 1997 during a flight from Jakarta, Indonesia, to Singapore, killing all 104 passengers and crew.

A US investigation found that the Boeing 737 had been deliberately crashed, but an Indonesian investigation was inconclusive.
Mozambique officials have been investigating a crash that killed 33 people in November.
They say preliminary investigations indicate that the pilot of the Mozambican Airline plane bound for Angola intentionally brought it down, and they're continuing to look into his possible motives.
A 2014 study by the Federal Aviation Administration indicates that in the US at least, flying remains a remarkably safe mode of transport and pilot suicide is a rare occurrence.
The study found that during the 10 years ending in 2012, just eight of 2,758 fatal aviation accidents in the US were caused by pilot suicide, a rate of 0.3 per cent.