The inability of searchers to locate the flight data and cockpit voice recorders aboard the ill-fated Air France Flight 447 has prompted Airbus, the manufacturer of the A330- 203 (F-GZCP) involved, to consider redesign of the critical air safety devices so they broadcast the crucial data in advance of a crash.
Currently, the Digital Flight Data Recorder (DFDR) and Cockpit Voice Recorders (CVR) —the so-called ‘black boxes’—simply serve as recording devices. The DFDR collects data from aircraft systems, while the CVR records crew conversation and aural warnings heard on the flight deck. The DFDR holds 25 hours of data on 88 flight parameters while the CVR the final two hours of cockpit audio.
Presently, the devices must be recovered in the wake of an accident after which information can be retrieved from the DFDR and CVR in a laboratory by skilled technicians. As designed, a DFDR and a CVR do not transmit real time information from an aircraft.
The DFDR and CVR work separately from a jetliner’s Aircraft Communications Addressing and Reporting System (ACARS), an air-to-ground link that automatically sends operational information, maintenance data and fault reports to the ground. But ACARS does not offer the bandwidth needed for real-time transmission of all the data stored in the DFDR and CVR.
As hope of finding the flight data and cockpit voice recorders on Flight 447 fades, Airbus has launched a study for improving flight data recovery, including, but not limited to, implementation of extended data transmission from commercial airliners, so that in the event of accidents, critical flight information can still be recovered and provided to accident investigation authorities even if finding the black boxes prove futile.
Tom Enders, president and CEO of Airbus 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 centers 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.”
The study will be conducted by Patrick Gavin, head of airbus engineering, and Charles Champion, who is responsible for customer services. The study will address technological issues as well as data protection and privacy concerns. Airbus says it will collaborate with other aerospace companies, research institutions, and international airworthiness and investigation authorities in conducting the study. The aircraft maker did not cite a timeline for completion of the research effort.
With Flight 447’s black boxes nowhere to be found despite an extensive search by a flotilla of ships trawling the Atlantic waters, and with the homing signals fading fast, observers have questioned whether a revamped system for broadcasting the data would make successful recovery of the devices far less crucial.
But Forbes magazine quotes an expert as saying this is easier said than done. “The black box is invaluable, but transmitting it would be very difficult as there are 50 to 100 separate constant streams of data recording different things that come into the recorder simultaneously,” said Keith Mackey, president of Mackey International, an aviation consultancy specializing in aviation safety and accident investigation. “It would send mountains of irrelevant data. We would have to have satellites to receive the data from all flying aircrafts. And the data would have to be transmitted to the ground with some way of recording it.”
Business Week agrees. “The volume of information you’re talking about is infeasible in terms of what it would cost to do that for every airplane,” quoting Ray Oishi, a senior engineering fellow at Annapolis, MD-based ARINC, which transmits texts and other data for airline customers. Airlines would also discard virtually all the routine data that was sent. “Just because it’s imaginable doesn’t mean it’s practicable.”
Research on developing improved DFDRs and CVRs aside, finding the missing Air France black boxes would certainly help matters since most of what we learned on July 2 from the investigating team only served to deepen the mystery behind the loss of the Airbus A330 on June 1, which killed all 219 passengers and 16 crew members on board.
Air France Flight 447 had departed Rio de Janeiro bound for Paris. It flew into stormy weather and ACARS maintenance messages transmitted from the stricken jetliner near the equator to a maintenance base in Paris indicated that inconsistent speed measurements prompted by iced over pitot tubes could have played a role in the fatal crash, the worst in Air France’s history.
Still missing are the A320’s flight data and cockpit voice recorders, thought to be resting deep under water. Ships continue to troll the search area, pulling U.S. Navy underwater listening devices attached to 19,700 feet of cable.
Meanwhile, the European Aviation Safety Agency (EASA) is mulling over whether to require all airlines to replace Thales-made pitot tubes on their Airbus A330s.
There are currently 600 Airbus A330 jets in revenue service, operated by 72 air carriers. After the loss of Flight 447, many carriers, including Air France, replaced the air speed sensors as a precaution.
Airbus had recommended replacing the devices after determining that they could be susceptible to icing. But neither EASA nor the FAA considered the risks posed by pitot tube icing to be significant enough to justify making replacement of the sensors mandatory.
The Flight 447 preliminary accident report by France’s Bureau d’Enquetes et d’Analyses, or BEA, runs over 125 pages, but it is remarkable how few facts have so far been established.
At the very least, the BEA crash investigators said they determined that the Air France jetliner that plunged from a stormy sky was intact when it smacked belly-first into the Atlantic Ocean at high speed. But they admitted that they still have no clear idea what caused the disaster.
Alain Bouillard, who is heading the accident probe, said “today we are indeed far from establishing the causes of the accident. The investigation is a big puzzle. Today we only have a few pieces of the puzzle which prevents us from even distinguishing the photo of the puzzle.”
According to Bouillard, the following facts have been established:
- the crew possessed the licenses and ratings required to undertake the flight.
- the airplane possessed a valid Certificate of Airworthiness, and had been maintained in accordance with the regulations.
- the airplane had taken off from Rio de Janeiro without any known technical problems, except on one of the three radio handling panels.
- no problems were indicated by the crew to Air France or during contacts with the Brazilian controllers.
- no distress messages were received by the control centers or by other airplanes,
- there were no satellite telephone communications between the airplane and the ground.
- the last radio exchange between the crew and Brazilian ATC occurred at 1 h 35 min 15 s. The airplane arrived at the edge of radar range of the Brazilian control centers.
- at 2 h 01, the crew tried, without success for the third time, to connect to the Dakar ATC ADS-C system.
- up to the last automatic position point, received at 2 h 10 min 35 s, the flight had followed the route indicated in the flight plan.
- the meteorological situation was typical of that encountered in the month of June in the inter-tropical convergence zone.
- there were powerful cumulonimbus clusters on the route of AF447. Some of them could have been the centre of some notable turbulence.
- several airplanes that were flying before and after AF 447, at about the same altitude, altered their routes in order to avoid cloud masses.
- twenty-four automatic maintenance messages were received between 2 h 10 and 2 h 15 via the ACARS system. These messages show inconsistency between the measured speeds as well as the associated consequences.
- before 2 h 10, no maintenance messages had been received from AF 447, with the exception of two messages relating to the configuration of the toilets.
- the operator’s and the manufacturer’s procedures mention actions to be undertaken by the crew when they have doubts as to the speed indications.
- the last ACARS message was received towards 2 h 14 min 28 s.
- the flight was not transferred between the Brazilian and Senegalese control centers,
- between 8 h and 8 h 30, the first emergency alert messages were sent by the Madrid and Brest control centers.
- the first bodies and airplane parts were found on June 6.
- the elements identified came from all areas of the airplane.
- visual examination showed that the airplane was not destroyed in flight ; it appears to have struck the surface of the sea in a straight line with high vertical acceleration.
Some of the messages suggest systems going off line, including the automatic throttle, the autopilot and the sensor that detects rapid changes of wind. There was a warning the cabin pressure was changing, and that the plane was operating with reduced fly-by-wire capabilities. The lack of a ‘mayday’ and the fact that no inflated life vests have been found, indicate that the jetliner dived into the ocean quickly and without warning. But the problem with this preliminary information is determining whether it represents the symptoms of technical failures, or the cause of them.
The apparent failure of the Pitot tubes was “a factor,” Bouillard said, but only one of several, including high winds, thunder, lightning and other possible equipment failures or human errors that remain unknown.
Although the homing signals on the black boxes should have weakened or shut off at the end of June, Bouillard said the acoustic search would go on until July 10. After that, through mid-August, searchers will employ diving equipment, towed sonars and unmanned underwater vehicles in hope of spotting the devices.
As regards the lack of any airworthiness directive regarding the A330, Bouillard said he saw no reason at this point to ground the A330 or for passengers not to board them with confidence. “As far as I am concerned, there is no problem flying these aircraft,” he told reporters near Paris. “There’s nothing to suggest they are unsafe. There are 660 of them flying that have flown millions of miles.”
An Air France pilots’ union accuses French and European air safety bodies of failing to prevent the crash of Flight AF447 by ignoring warnings about the faulty pitot tubes,
The SPAF union wrote to France’s DGAC aviation authority and the European Aviation Safety Agency (EASA), accusing both of ignoring a string of incidents involving the airspeed devices. Arnoux said it was the “responsibility” of both agencies to require Airbus to replace the pitot tubes.
“For years the crews of A330/340 aircraft have been reporting cases of loss or variation of airspeed data in severe weather conditions,” SPAF head Gerard Arnoux said in the letter. “Appropriate measures” from either agency would have “helped prevent the sequence of events that led to the loss of control of the aircraft,” he charged.
The Air France pilots asked the BEA and the DGAC for details of their airline’s past problems with the pitot tubes. The pilot’s union said previous issues with the airspeed sensors constitute “serious incidents” that require both agencies to open technical investigations.
Meanwhile, the NTSB has released its preliminary finding in a June 23, 2009 incident involving a Northwest Airlines Airbus A330 flight in which the onboard computers switched off the aircraft’s autopilot possibly due in part to inconsistent airspeed indications.
The Airbus 330-323 (N805NW) operating as Flight 8 from Hong Kong to Tokyo, experienced an airspeed anomaly while in cruise flight at FL390 approximately 50 miles southwest of Kagoshima, Japan. The crew reported that they were in normal cruise and in visual conditions with some convective weather displayed on radar about 25 miles north of track, with thin cirrus clouds ahead.
After entering the cirrus and moderate precipitation and turbulence, the crew observed, (and the DFDR confirmed) that the autopilot and autothrust switch off, and the aircraft switched to Alternate Law. The master caution and warning messages were activated.
The crew followed flight manual procedures and the autopilot and normal law returned in about one minute, however the event quickly repeated itself, lasting for about two minutes. The crew turned the airplane 60 degrees off course to exit the weather as soon as the anomalous indications were observed. The autopilot, autothrust and other controls returned to functioning, but the airplane remained in alternate law for the rest of the flight.
The flight deck crew and the DFDR noted large airspeed fluctuations, small altitude fluctuations, and an overspeed alert. The flight continued to Tokyo, Narita airport and landed with no damage or injuries to the nine crew and 208 passengers on board.