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Laser speed sensor promises safer air travel

Wednesday, October 17, 2012 - 03:14

Oct. 17 - Australian engineers, motivated by the 2009 crash of Air France Flight 447, have come up with a laser speed sensor system for aircraft that they say will reduce the possibility of similar disasters. The Air France crash off the coast of Brazil was triggered by the icing of speed sensors on the exterior of the plane and, while the laser system is not designed as a replacement, its developers say it will greatly enhance flight safety. Elly Park reports.

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Dr. Sean O'Byrne from the Univerity of New South Wales says he's seen the light. He believes the deployment of his laser speed sensor system on commercial aircraft could save lives. For an airplane to liftoff and to stay in flight, one thing is critical - speed. Today, pilots rely solely on a system called Pitot tubes to tell them when they've reached optimal speed. The tubes, located outside the aircaft below the cockpit, measure the speed of air rushing through them and transmit that information to the pilot. But this system is not reliable when conditions are extremely cold. O'Byrne demonstrates why. (SOUNDBITE) (English) DR SEAN O'BYRNE, ENGINEERING LECTURER, UNIVERSITY OF NEW SOUTH WALES, SAYING: "We've currently got a speed of about seven metres per second, which is a fairly brisk wind that the pitot tube can measure the speed of quite accurately. But the one problem that it has is this little hole at the end here, which can get iced up if conditions get very cold at high altitude." And when the tubes ice up, they send faulty data to the captain. Iced up tubes have triggered plane crashes around the world, including the crash of Air France Flight 447 in 2009 that killed all 228 people on board. Flight 447 stalled over the Atlantic, just as Captain Gary Hartley demonstrates in a flight simulator. (SOUNDBITE) (English) CAPTAIN GARY HARTLEY, AIRLINE PILOT, SAYING: "If we just keep on introducing this potential here in our simulator, as we get close to it, the aircraft will develop a shaking control column. And here we see it's trying to climb, can't do it, and we'll all of a sudden enter... There it is. It's starting to become uncontrollable, and now it's about to plummet out of the sky." But O'Byrne says his laser-based system could help prevent such a catastrophe. He says it would be unaffected by freezing conditions while utilising the physics of the Doppler Effect. (SOUNDBITE) (English) DR SEAN O'BYRNE, ENGINEERING LECTURER, UNIVERSITY OF NEW SOUTH WALES, SAYING: "What we do is we get two laser beams, one pointing towards the airstream and one pointing away from the airstream, and the difference between the frequencies of those two laser beams is what we measure, and that tells us the speed." The lasers can be placed inside the body of the plane between the tail and the top of the fuselage allowing for better control and faster readings. An aircraft-ready design is in the works, and while not meant to replace the Pitot tubes entirely O'Byrne and his team believe that their lasers will point the way to safer air travel.