Airbus did not break up in flight
Air France Flight 447, the Airbus A330 that crashed in the mid-Atlantic at night a month ago “did not break up or become destroyed in flight,” but contacted the ocean surface belly first and apparently upright at a high rate of descent.
This revelation by the French Bureau d’Enquêtes et d’Analyses has put to rest major concerns that in-flight separation of the vertical stabiliser tail fin might have been causal to the accident.
The preliminary BEA findings released by French air accident investigator Alain Bouillard said a visual study of recovered aircraft remains showed the tail fin was still attached to the aircraft’s fuselage on impact.
Cabin interior components recovered include bulkheads, galley, ceiling or floor panels, seats, overhead baggage bins, cabin and hold lining, and externally the tail fin and part of the nose-mounted radome.
The report says: “The middle and rear fasteners with the related fragments of the fuselage hoop frames were present in the fin base. The distortions of the frames showed that they broke during a forward motion with a slight twisting component towards the left.”
A summary of the component study says: “Observations of the tail fin and on the parts from the passenger (galley, toilet door, crew rest module) showed that the airplane had likely struck the surface of the water in a straight line, with a high rate vertical acceleration.”
Bouillard said however that BEA did not yet have autopsy results from the recovered bodies. About 30 bodies were recovered by the Brazilian Navy, but Brazil has not yet released the autopsy data.
No evidence of fire or explosion has been found, and hopes are fading for the recovery of cockpit voice and flight data recorders although Bouillard says searches will continue for another ten days – more than a week after the recorders’ locator beacon batteries would normally have expired.
Bouillard said the primary cause of the crash was still unclear. “I don’t know why nobody survived,” he said in a media briefing. “I don’t know the intensity of the impact. Perhaps we will find out from the autopsies. Perhaps we will never know.”
He added that the pitot tube airspeed sensors were a factor but not the cause of the accident.
Investigations will also focus on why air-traffic controllers seem to not have been monitoring the flight when it went down, reasons for a five hour delay in initiating a search, and the fact that at least three other flights in the same area made significant diversions from their flight plans to avoid cumulonimbus (thunderstorm) cloud formations.
Mr Bouillard said there was concern about the length of the delay between the crew failing to contact air traffic controllers in Dakar, western Africa, as planned and the alarm being raised.
The only documented data available to the investigation that originated from the aircraft was a burst of 24 automatically sent messages from the aircraft’s Aircraft Communications Addressing and Reporting System (recovered), which included incorrect airspeed and temperature readouts, disengagement of the autopilot and autothrottle, and disconnection of the rudder travel limiting system which limits available rudder travel depending on airspeed, to prevent overloading of the fin’s structure.
Meanwhile Airbus Industrie has launched a study on reinforcing flight data recovery, including, but not limited to, extended data transmission for commercial airliners, so that in the event of accidents, critical flight information can still be recovered and released to investigating authorities.
Airbus President and CEO Tom Enders says: “Gathering information from accidents is vitally important to further improve the safety of flying. Various technical means for reinforcing flight data recovery and data transmission to ground centres are principally available. We will now study different options for viable commercial solutions, including those where our experience with real-time data transmission from our own test aircraft could support the further development of such solutions.”
Airlines do not receive direct information from aircraft Digital Flight Data Recorders (DFDR) and Cockpit Voice Recorders (CVR) – the so-called “Black Boxes”. The DFDR collects data from aircraft systems, while the CVR records crew conversation and aural warnings. Presently, the only possible means to retrieve information from the DFDR and CVR is to process them on the ground with very specific ground tools. DFDR and CVR do not transmit real time information – that responsibility is managed and controlled by the investigation authorities.
Retrieving the DFDR and CVR when aircraft are lost continues to be a major challenge for the entire aviation community. Today’s existing air-to-ground links for ACARS maintenance data transmission do not offer the bandwidth that would be needed for a fully real-time transmission of all the data stored in the DFDR and CVR. Airlines and maintenance staff can however use ACARS to derive real-time data from aircraft engines and other systems.
Airbus says the study will be conducted by Patrick Gavin, Head of Airbus Engineering, and Charles Champion, Head of Customer Services, and will need to address technological issues as well as data protection and privacy concerns. Airbus will include industrial partners, research institutions, and international airworthiness and investigation authorities in the study.
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