Investigators have successfully recovered all the data from the two recorders that went down with Air France Flight 447 two years ago. The recorders were found last month and recovered last week from the wreckage of the Airbus A330 that crashed on a late night flight from Rio de Janeiro to Paris when it flew through areas of convective activity over the Atlantic Ocean. Debris was spotted the next day. It took nearly two years, however, to locate the wreckage on the ocean floor.
What happened to 447 is a deep mystery though theories abound, from a simple and tragic thunderstorm encounter to pitot problems to some kind of failure of the fly-by-wire flight control system. What happens now that the data has been recovered? It’s high-tech detective work of the highest order and involves some surprisingly pedestrian steps. Joe Kenney from Honeywell, the company that made the digital flight data recorders in Air France 447, told me that the process of downloading the data, once the recorders have been recovered, is really quite simple.
It’s not uncommon, according to Kenney, for there to be only partial data recovery on crashes with a great impact and a fuel-fed fire. In the case of the Air France crash, however, such was not the case. The impact, based on the evidence found on the surface shortly after the disaster, suggest that the impact was not tremendously high, and there was no evidence of pre-impact fire.
If after it is recovered, the card is intact, the data is simply downloaded to a PC, put onto a spreadsheet and read. It’s a good bet that investigators are poring over that data as I write. Once armed with the data, investigators from the airframer can plug the data into a flight simulation model and watch the flight path of the airplane and the actions of the crew.
The cockpit voice recorder, which was also made by Honeywell, records a 2-hour loop of cockpit voice data. It is a digital file that investigators can simply listen to. If you’ve ever heard one, these recordings--the very last seconds are often redacted in transcripts for obvious reasons--are chilling. It is also likely that investigators have already heard them.
Even with a thousand flight parameters recorded, everything from aileron position to pilot input, and the cockpit voice recordings, it’s still not certain that the cause of the crash will be determined. Investigators often disagree, though not on what the data is but on what the data means. How the crew reacted to the emergency and how their conversation and work in the cockpit supports those theories, leave much to the judgment of the human investigators.