Sixteen bodies have now been recovered from the wreckage of Air France Flight 447, but the cause of last week's crash is still a mystery. New reports say at least a dozen other flights traveling in the same area at around the same time had no problems with weather conditions.
John Cox is president and CEO of Safety Operating Systems. He’s flown Airbus jetliners and is familiar with their controls and systems. He spoke to John Roberts on CNN’s “American Morning” Monday.
John Roberts: What do you make of this idea that some 12 other planes flew through that area? Air France had four flights, a couple from Sao Paulo, and others went through that area of thunderstorms without any problems.
John Cox: Well I think it says the weather itself is probably not the single cause for the accident. This accident, just like all I've been associated with, will end up being a series of events. We'll end up learning that series one piece at a time to understand what happened.
Roberts: Air France sent out some literature over the weekend regarding one of the air speed indicator sensors, the Pitot tube, and there might be some problem with that. With your knowledge of Airbus…What do you know about problems with anomalous speed readings?
Cox: The fleet has shown a little bit of this issue to come up before. I'm aware of three or four previous cases in fleet history but it's typically been short duration. What we learned by the information that the airplane up-linked to the Air France maintenance facility, is they had a lot of very confusing signals that the pilots would have been confronted with. And exactly what caused that, it could possibly be Pitot tubes or air speed indications that would be causal in some way but why the crew was not able to satisfactorily determine which of the air speed indicators was bad, there's a procedure for it. Where that procedure either wasn't acted on properly or failed, that's going to be something the investigators are really going to have to look into carefully.
Roberts: According to Air France, there have been some problems with this sensor icing over in certain conditions. Could that potentially have happened at an altitude of 35,000 feet, flying through the thunderstorm area? Could that sensor possibly have iced over and therefore given incorrect speed readings?
Cox: It's possible. Usually at cruise altitude it is so cold you really don't get a lot of icing. But this particular sensor has shown on rare occasion this icing issue to come up at cruise before. I think the fact there's something unique here, that as an accident investigator, when you find something unique you really want to concentrate and look to see if that could have an effect on the accident.
Roberts: There has been a problem, as you mentioned, at cruise. This showed up in October of last year with a Qantas airliner that was flying in the South Pacific area. Three hours into the flight, everything seemed to be going fine. The computer which controls the aircraft with the autopilot on suddenly got these different speed readings and went haywire thinking it was going too slow. It put the plane into a dive to pick up speed. Apparently 100 people were injured as they were knocked into the roof of the cabin. Could something like that potentially have happened here, and while the pilots recovered from that maneuver, if you’re flying around thunderstorms with updrafts, cross currents and lightning in the area, could that have maybe caused the catastrophic cascade of events?
Cox: I don't think so. In the case of the Qantas airplane, the failure was from an air data inertial reference unit, known as an ADIRU. It broadcast some spurious information and the airplane reacted, the autopilot system attempted to follow it. Although the ADIRU on the Air France accident airplane also displayed some problems, it was a failure-type message. So I don't believe we're going to see anything that would connect these two. The Air France airplane has a number of system failures that the Qantas airplane did not. Also, these ADIRUs are pretty reliable and you don't see that. Additionally, the autopilot on the Air France airplane had disconnected, so you put all that together and I don't believe we're going to end up seeing a correlation between the Qantas and Air France airplanes.
Roberts: What do you think about the potential for foul play here?
Cox: As an investigator, until you know exactly what caused it, you need to leave everything on the table. I wouldn't rule it out but there's been nothing right now that shows me it would be a prime suspect.