BEA's final report on the crash of Air France AF-447

Image courtesy BEA

France's Bureau of Investigations and Analysis’ (BEA) submitted its final report on the crash of Air France flight AF-447 flying from Rio de Janeiro to Paris, killing all 228 passengers and crew on-board.

The final report essentially re-states what has already been released till date.

The crash commenced with ice crystals blocking the pitot tubes, sending false information to the flight computers and causing the autopilot to shut down while the plane was at cruising altitude, and a reconfiguration of flight controls to alternate law.

A confluence of factors, including a barrage of alarms coupled with inadequate training of the flight crew, and false sensor readings, completely surprised the crew. As per the report "The crew likely never understood that it was faced with a ‘simple’ loss of all three sources of airspeed information.”

In a series of errors, the pilots relying on erroneous readings never recognised they were in a stall and kept nosing the Airbus A330 aircraft upward, rather than downward as was necessary. Chief investigator Alain Bouillard said "The crew was in a state of near-total loss of control". Ironically the flight captain, who was on a rest break, did not return to the cockpit until it was too late.

The BEA has passed the blame all around and its recommendations call for more training of pilots, an improved layout of cockpit instruments and warning systems to help crew better recognise and manage unusual flight situations, and thorough review of the flight director software..

Investigators recommended that the European Aviation Safety Agency (EASA) require the aircraft manufacturer Airbus S.A.S. to review the flight director’s design and to possibly modify the software so that it either disengages permanently in the event of a stall or displays “appropriate orders” when a stall warning is set off.

Read more details at the BEA's page for AF-447.
Read the final report here.
Read the final report summary here.

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EASA proposes Airworthiness Directive on Airbus A330/A340 Thales pitot probes

The European Aviation Safety Agency (EASA) has released a Proposal for an Airworthiness Directive (PAD) requiring all Airbus A330 and A340 aircraft currently equipped with Thales pitot probes should be equipped with Goodrich pitot probes on position 1 (Captain) and 3 (Standby) instead, while pitot probe 2 (first officer) should be upgraded to the enhanced Thales pitot probe type BA or to the Goodrich pitot probe.

The PAD reasons

Occurrences have been reported on A330/340 family aeroplanes of airspeed indication discrepancies while flying at high altitudes in inclement weather conditions. Investigation results indicate that A330/A340 aeroplanes equipped with Thales Avionics pitot probes appear to have a greater susceptibility to adverse environmental conditions than aeroplanes equipped with Goodrich pitot probes.

A new Thales Pitot probe Part Number (P/N) C16195BA has been designed which improves A320 aeroplane airspeed indication behaviour in heavy rain conditions. This same pitot probe standard has been made available as optional installation on A330/A340 aeroplanes, and although this has shown an improvement over the previous P/N C16195AA standard, it has not yet demonstrated the same level of robustness to withstand high-altitude ice crystals as the Goodrich P/N 0851HL probe. At this time, no other pitot probes are approved for installation on the A330/A340 family of aeroplanes.

Airspeed discrepancies may lead in particular to disconnection of the autopilot and/or auto-thrust functions, and reversion to Flight Control Alternate law, which would cause an increase of pilot workload. Depending on the prevailing aeroplane altitude and weather, this condition, if not corrected, could result in reduced control of the aeroplane.

For the reasons described above, this AD is a precautionary measure and requires the removal from service of all Thales Avionics P/N C16195AA pitot probes, the replacement of Thales Avionics P/N C16195BA pitot probes at positions 1 (Captain) and 3 (Stand by) with Goodrich P/N 0851HL probes and the installation at position 2 (First Officer) of a Thales Avionics pitot probe P/N C16195BA. This AD is considered to be an interim measure and further AD action cannot be excluded.

The upgrade is to be accomplished within 4 months after the Airworthiness Directive (AD) becomes effective. EASA is open for consultation on this proposal until September 7 2009.

Readers will observe the Aero-Instruments 0851HL-AI Pitot Probe , recently approved by the US Federal Aviation Administration for use on all Airbus A320/A330/A340 families of aircraft, is not mentioned in the EASA PAD.

Hat tip to Simon Hradecky at AVHerald for the story.

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Aero-Instruments Pitot Probe approved by FAA for use on Airbus aircraft

The U.S. Federal Aviation Administration (FAA) has approved the Aero-Instruments 0851HL-AI Pitot Probe as a replacement part on Airbus Airbus A318, A319, A320, A321, A330 and A340 series airplanes airplanes flown worldwide.

Each Airbus commercial aircraft has three Pitot Probes, which are the primary air speed sensing components on aircraft and are designed with integrated electrical heaters to prevent icing.

The Pitot Probes made by another vendor, Thales of France, have been under suspicion in the crash of Air France AF-447. In addition to the standard AA type probes of Thales, even the new modified BA type probes are under suspicion after a recent incident involving an Air France A320 aircraft registration F-GFKJ where all airspeed information as well other air data related indications were lost in the cockpit, and the autopilot and autothrust systems dropped off-line.

In granting Parts Manufacturer Approval (PMA) for the Aero-Instruments 0851HL-AI Pitot Probe, the FAA concluded that the part meets or exceeds the agreed upon certification plan, which was based on the requirements of TSO C-16A, including the icing requirements outlined in SAE AS393, AS8006, and BS2G.135.

Aero-Instruments will be the third manufacturer of these Pitot Probes. The other being Goodrich of the US.

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Air France #AF447: The search so far - some great sources of information - IAG and ATI

The search and recovery operations go on for Air France AF-447, as does my search for information. Some information I recommend as well worth reading and listening.

My good friend Addison Schonland at IAG has created and continues to create a nice series of articles and podcasts on AF447.

• A decoding and analysis of the ACARS messages
• A podcast of an interview with an avionics engineer familiar with the Honeywell ACARS system fitted on board the Air France Airbus A330-203 F-GZCP.
• A podcast of an interview with experienced commercial pilot, Doug Willey who explains the pre-flight procedures as well as how a flight tracks its route.
  
• A podcast of an interview with Dr. John Craven, a veteran on many underwater search operations, on the challenges to locate the "black boxes" flight data and cockpit voice recoders from the ill-fated flight from Rio to Paris.

This article on CNN written by Kieran Daly, Editor of Air Transport Intelligence is also a "must read".

For those Bangalore Aviation readers of a more technical mind-set - we have been hearing a lot about the possible freezing of the pitot probes (also called pitot speed sensors) on the Airbus A330, and the replacement being offered by Thales. Thales a French company, was the vendor for the pitot probes most likely model C16195BA on the Air France aircraft.

Goodrich is also a vendor of pitot tubes on Airbus aircraft and a competitor to Thales. The product documentation of their new model 0851HL pitot probe which is a replacement for the older model 0851GR pitot probe, is also very conveniently positioned as a replacement for it's "competitor" - read Thales. The document makes some very interesting reading on the icing problem that afflicts the older pitot probes and what changes have been made to address the problem.

I must caution that I am no way implying, nor should we in any way assume, that Thales products are inferior to those of Goodrich.

All said and done we still have to wait for facts and Kieran's words best summarises my feelings "But the fact remains that this is today speculation".

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