Why the Germanwings A320 went down: Experts speculate
Investigators examining the Germanwings crash will focus on a near disaster late last year in which another Germanwings plane plunged 3000ft out of control.
The incident that was cause by two critical sensors being blocked and was the subject of an urgent advice to all airlines.
In that incident the pilots managed to regain control of the A321 which had 109 passengers aboard.
A European Air Safety Agency investigator said the problem related to all Airbus A318, A319, A320 and A321 – including the Airbus A320 involved in yesterday’s tragedy.
EASA warned that if the sensors malfunctioned the flight control computers would order "a continuous nose-down pitch rate" that in a worst case scenario could not be stopped.
Late last year Jetstar issued a warning to its pilots about the problem.
Jetstar issued a four page instruction to pilots on how to overcome the problem.
The key question for aviation experts is why there was no mayday call from the Airbus A320 while the plane plunged 31,000 feet in eight minutes.
The flight was from Barcelona to Dusseldorf.
Civil aviation authorities have told media it was the combination of the loss of radio contact and the descent that caused the control room staff to send out a distress call.
A former investigator with France’s Bureau of Investigation and Analysis for the Security of Civil Aviation, who spoke to media on the condition of anonymity, said lack of a distress call “opens up all possibilities.”
The main theories aviation experts are pointing to at the moment are either a technical problem or pilot and crew error, news.com.au reported.
But a terrorist hijacking cannot yet be ruled out.
The plane is a ‘workhorse’ of the fleet, flying 5.3 flights a day over its 24 years. A theory that rapid decompression caused by corrosion and metal fatigue took place has been widely reported. Experts point to the 1988 crash Aloha Airlines Boeing 737-200. The plane lost a large part of its roof.
Flight 9525 reportedly descended at 3,000 feet per minute from its cruising altitude of 38,000, twice the normal speed of a descent. Experts say this rate of decent could be to get the plane down to 10,000 feet, where the air becomes breathable again.
Another theory is that the pilot accidentally put the plane into dive or stalled the plane and was not able to recover from it. The pilots could have made an error while they were trying to get the plane down to breathable air.
