What caused germanwings flight 4U9525 to crash?

Blocked probes the possible cause of Germanwings flight 4U9525 crash?

Geoffrey Thomas and Sharon Petersen, AirlineRatings

25 Mar 2015

Blocked probes the possible cause of Germanwings flight 4U9525 crash?

Whilst the answer to this question won't be fully known until the black box recordings are evaluated, crash investigators will be focusing on a near disaster involving a Lufthansa A320 aircraft that occurred late last year when a sister plane to the one that crashed yesterday plunged 3000ft out of control.

The incident that was caused by the blocking of two critical sensors –Angle of Attack Probes- was the subject of urgent advice to airlines across the globe.

In that incident the pilots managed to regain control of the A321 which had 109 passengers aboard.

According to crash investigator the European Air Safety Agency (EASA), the problem related to the Airbus A318, A319, A320 and A321 – including the Airbus A320 involved in yesterday’s tragedy.

EASA warned that if the probes malfunction the flight control computers “order a continuous nose down pitch rate that, in a worst case scenario, cannot be stopped with backward sidestick inputs, even in the full backward position.”

Late last year Jetstar issued a warning to its pilots about the problem. It said: “An occurrence was reported by another operator where an Airbus A321 aircraft encountered a blockage of two Angle Of Attack (AOA) probes during climb, leading to activation of the Alpha Protection (Alpha Prot) while the Mach number increased."

Jetstar issued a four page instruction to pilots on how to overcome the problem.

Image of Germanwings flight 4U9525 debris

One of the largest pieces of debris from the Germanwings airpane. The debris field stretched over 2kms.

This is the second Airbus A320 to have crashed in just under three months. As one of the world's most popular aircraft utilised by hundreds of airlines around the world the answer to the question "why?" is more important than ever. 

Sadly, yesterday's crash was the third most deadly involving an A320. In 2007 a TAM Linhas Aereas A320 shot off a runway in Brazil, killing 187 people, while 162 people died when an Indonesia AirAsia jet crashed in the Java Sea in December.

One of the plane's black box recorders has been found at the crash site, about 100 km (65 miles) north of the Riviera city of Nice, and will be examined immediately, France's Interior Minister said. We can expect to have information from the black box within 72 hours. 

The Germanwings A320 carrying 150 people on-board was travelling between Barcelona and Dusseldorf when it crashed in the French Alps near Digne. Flight 4U9525 departed Barcelona, Spain at 10:00am CET bound for Dusseldorf.  The flight reached cruising altitude(38,000 ft) at 10:27. At 10.31, the airplane started losing altitude and dropped off radar at 10.40 CET.  According to Aviation Herald radar data, the plane descended from 38,000 ft through to 11,000 ft in 8 minutes at an average of 3,375 feet per minute.

The A320 appeared to have levelled off at an altitude of 6,800ft for about one minute while on a north easterly heading.

However mountains rise up to 8,600 feet about one mile north of the last reported position of the plane.

French civil aviation authorities said they lost contact with the plane and declared it was in distress at 10:30am (8:30pm AEDT).
see what happened in the lead up to the crash of germanwings flight 4U9525
How the tragic crash of Germanwings flight 4U9525 unfolded killing all 150 on-board

"The crew did not send a Mayday. It was air traffic control that decided to declare the plane was in distress because there was no contact with the crew," an official said.

It is believed 67 German and 45 Spanish nationals were on board the flight, including two babies. Also on board were two Australians.

The Germanwings A320, registration D-AIPX, was one of the older A320s flying at 24 years of age and had previously belonged to Lufthansa. 
A piece of wreckage showing the planes registration number


The airline's managing director,Thomas Winkelmann, said routine maintenance of the aircraft had been carried out the day before, and said the company would work closely with investigators. Lufthansa, one of the world's safest airlines, owns and maintains Germanwings aircraft and until now, scored a perfect seven stars on the airlineratings safety rating.  

According to Airbus, the aircraft had accumulated approximately 58,300 flight hours in some 46,700 flights. It was powered by CFM 56-5A1 engines.