They've released [ref.1] the final report for the disappearance of Flight 447, a 200 ton Airbus which disappeared in June 2009 on its way from Rio de Janeiro to Paris. About 4 hours into the flight, somewhere over the Atlantic, in night-time stormy weather, contact with the airliner was completely lost.
A day later, a Brazilian Air Force search-plane spotted some oil spill – later confirmed as from a passing tanker.
5 days after the disappearance a Brazilian search team located 2 male bodies, a seat, a backpack with a computer, and a leather briefcase with a boarding pass for Flight 447.
6 days after the crash, the vertical stabilizer or tailpiece was found.
9 days after the crash the French nuclear sub “Emeraude” arrived at the suspected zone, about 600 miles off the Brazilian coast, and where the Atlantic has some of its deepest regions. The sub was to listen for the black box pingers, which typically have a battery lifetime of about 30 days, and it was to work with the mini sub (Nautile), which can descend to 20,000 feet. The Nautile is titanium-hulled, electric-powered, can hold up to 3 people – and has over 90 trips down to the Titanic under its belt.
16 days after the crash, 50 bodies had been recovered, in 2 distinct groups, 50 miles apart, by French, Spanish and US teams. Today, there are still 74 bodies that have never been found.
The essay I wrote in 2009, 3 weeks after that disappearance, ended with a hope that the little pingers might be heard, although there was only roughly a week left. They never were, and the wreckage, and thus the black boxes, could not be located. It would actually take two years and millions of dollars before the Airbus was found. In May 2011, one of three unmanned mini subs, trawling 750 square miles in half mile swaths, came across the site, and shortly thereafter the Cockpit Voice Recorder was found. The depth was 12,000 feet, similar to that of the Titanic.
Last summer, July 2012, the final report came out. The crash was nothing to do with terrorism, and everything to do with airspeed confusion.
The captain had had only about an hour of sleep before taking off with his 2 co-pilots and 12 crew plus 216 passengers, and he handed over to the co-pilots after about 4 hours of the roughly 10 hour flight.
The first sign of problems was when the autopilot disengaged, apparently because of conflicting information on air speed – which is information that comes from classic PITOT tubes that many learn about in science classes. These PITOT tubes had apparently iced up, at 38,000 feet. There is a statement on the voice recorder that says “... we don't have any more indications...” meaning concerning speed. And the co-pilots, apparently panicking, put the Airbus into a climb, which ultimately caused a stall. Because of that high altitude stall, at night time, with the pilots not understanding what was happening, the plane dropped to the sea within about 3 ½ minutes. It turns out that it broke apart upon impact.
Hans Weber, a physicist by training, said “...if you're at a high altitude, and you carry on climbing at 5 degrees, you will lose control... it's what pilots call the 'coffin corner' – you're running out of lift in the thinner air...”
Is there anything to be learned from this tragedy? Yes, three years and tens of millions of dollars later, we have to perfect speed sensors, and we have to prepare pilots if, god forbid, a plane should ever again encounter conditions leading to the possibility of such a high altitude stall. In other words, automation is good only up to a point.
1. BEA (Bureau d'Enquetes et d'Analyses) at Le Bourget Airport; Final report, July 5 2012.
Dr. David Nightingale is Professor Emeritus of Physics at the State University of New York at New Paltz, and is the co-author of the text, A Short Course in General Relativity.
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