Possible causes of the Germanwings A320 crash in the French Alps
- French aviation authority confirmed that the aircraft did not issue a distress call
- One of the two black box flight recorders on board was recovered
- Aviation experts said it could take up to a year to reach a reliable conclusion
The cause of the GermanWings flight 4U9525 crash in the French Alps on Tuesday remains unclear.
Read more: Full coverage of the Germanwings Airbus A320 crash
The main focus is on the sudden, 8-minute drop in the plane from an altitude of 38,000ft to 6,000ft where it then disappeared from radar.
Nevertheless, one of the two black boxes or flight recorders on board was recovered. This device recorded the voices and ambient sound in the cabin during the flight's last minute. Though damaged, French transport minister, Alain Vidalies said that if voices have been recorded by the cockpit voice recorder, the investigation would proceed “fairly quickly”.
Some aviation experts said that it could take up to a year to reach a reliable conclusion.
“Inexplicable” reasons
Lufthansa's CEO Carsten Spohr said the crash was "inexplicable".
“It is inexplicable this could happen to a plane free of technical problems and with an experienced, Lufthansa-trained pilot,” he told journalists in Frankfurt.
Meanwhile, Germanwings pointed out an hydraulic problem or a failure in the gauges could have been behind the accident, and dismissed talk of a de-pressurisation of the aircraft's cabin.
Terrorist attack
French Interior Minister Bernard Cazeneuve said that the hypothesis of a terrorist attack had been discarded, as the concentration of the plane's wreckage over a surface area of 1.5 hectares suggests that the plane did not explode.
Problems with the servo actuator
The pilot may have fought to control the plane's inclination after a fault
In a statement, the London-based Institute of Mechanical Engineers was dismissive of an unexpected compression as the chief reason for the tragedy as the plane experienced a “relatively controlled drop”.
This suggests that the pilot “was fighting to control the plane's inclination, as a result of a problem in the servo actuator, which provides information about the plane's position and speed. We will have to wait for the black box data in order to verify that possibility.”
Frozen height sensor
Another hypothesis points to a problem with the height sensor, a problem that occurred in another Lufthansa flight between Bilbao and Munich on a A321 plane, similar to the Germanwings A320.
On that occasion, the angle of attack sensors (AOA) were frozen during the ascent of the plane, leading to errors in the altitude data. Lufthansa changed the sensors on all the A320 craft, but it has yet to be confirmed if the company removed the sensor from the Germanwings planes as well.
A computer error
Some sources have highlighted how a computer error may have been the main reason behind the catastrophe. The Spanish news site El Confidencial Digital states in its front page that a computer error could explain the unexpected loss of altitude that the plane experienced.
The same source mentioned that the two pilots may have lost consciousness as a result of a problem with the pressurisation in the plane's cabin. That would explain why they did not issue a distress call, as the French aviation authority confirmed on Tuesday.
Read more: Task of identifying Germanwings 4U9525 passengers begins