Crash 'perfect' for technical investigation

The investigation into what caused the crash of the Turkish airplane near Amsterdam is underway. Everything seems to indicate that the Boeing stalled. How could it happen?

How can a modern passenger aircraft like the Boeing 737-800 fall to the ground almost vertically, like a dead bird? Aviation experts are being cautious with their theories of how and why the Turkish Airlines plane crashed at Schiphol on Wednesday.

Investigations into the cause of air disasters can take months, sometimes even years. We might have answers sooner this time, however, since the conditions for the technical investigation are practically ideal. The aircraft was not destroyed by fire and all the debris is within a small radius of the crash site. The physical components on which the investigators will concentrate, the engines and wings, for instance, remained in good condition.

And the so-called black box – which is in fact orange: black is a reference to the unknown contents – with data about the flight and the conversations from the cockpit can be easily salvaged. “I expect there will be an explanation of the primary causes within a few weeks,” says Benno Baksteen, retired pilot and aviation expert. “Further investigation into deeper-lying causes can take much longer.”

Stalled

Everything seems to indicate that the Boeing stalled, says Baksteen. According to the laws of aerodynamics, upward pressure creates the ‘lift’ of an aircraft when there is sufficient forward acceleration. If the angle of approach is increased (due to a technical reason or an action by the pilot), the air no longer follows the ideal line along the wings and the plane stalls and slows down rapidly. That is fatal when close the ground, since there is no time to correct the plane’s motion and a crash is inevitable.

But Baksteen cannot say why the plane stalled to begin with. The fact that no fire broke out after the crash could indicate a lack of fuel and therefore the failure of both engines. This seems unlikely to Baksteen: “The captain is responsible for the amount of kerosene. Normally more than enough fuel is in the tank so that a plane can be diverted to another airport if necessary. You always make sure of that.” And if the plane was low on fuel because of a calculation error or other reason, the pilot would have noticed this during the flight and arranged to make an early landing somewhere along the route, Baksteen says.

Undershooting

Wind sheer (a sudden gust of wind) or a bird flying into the engine are also possible causes. Baksteen does not believe the crash could have resulted simply from the pilot ‘undershooting’ the runway as a result of a miscalculation. “That could only have been the cause if you end up 100 metres before the runway, and this aircraft is much further away.” Nor could it have been the plane itself. The ill-fated Boeing 737-800 was relatively new, delivered in 2002, and one of the most advanced types of aircraft.

Flying has become much safer over the past decades, partly thanks to developments in aircraft construction. 502 people lost their lives in aviation accidents last year, down from 692 in 2007. In the nineteen-sixties and seventies, when there were far fewer flights, the death toll per year was seldom below 1,000. Now only one in 1.2 million flights has an accident. The chance of surviving a crash has also increased. Last month all 155 passengers walked away from an A320 that made an emergency landing on the Hudson River in New York. On Wednesday 125 of the 134 passengers survived the crash at Schiphol.

Benno Baksteen: “Safety standards are now extremely high. That Boeing of Turkish Airlines really wasn’t on its last legs. But there’s always the chance of something unexpected. However well you do it, sometimes things go wrong.”