[cnn-photo-caption image=http://i2.cdn.turner.com/cnn/2009/WORLD/americas/06/02/brazil.missing.plane.search/art.rescue.plane.afp.gi.jpg caption="A Brazilian radar plane is fuelled up Monday at the Fernando de Noronha airport to search for Flight 447."]
Though searchers believe that they have found debris from an Air France jet that disappeared off Brazil's coast Monday, finding the entire plane and learning exactly what downed it could be a tedious, years-long process.
Many factors can complicate a search effort. Tradewinds and ocean currents can quickly scatter wreckage across several square miles, and the plane's altitude - almost 7 miles, in the case of Flight 447 - can make it difficult to pin down where the aircraft hit the water.
"It's a big ocean," said John Hansman, director of the Massachusetts Institute of Technology's International Center for Air Transportation. "Once you're offshore, you're no longer in direct radar contact."
It varies from airline to airline, but passenger jets generally send location reports every few hundred miles when they're over open water, Hansman said.
They also send out maintenance reports via satellite that provide the plane's location at a specific time. Some maintenance reports are routine; others are sent when a problem or malfunction is detected, Hansman said.
Flight 447 was carrying 228 passengers and crew members from Rio de Janeiro to Paris, France. About three hours into the journey, more than 200 miles off Brazil's coast, the jet transmitted 10 maintenance reports: one for each piece of malfunctioning equipment, the professor said.
About 10 to 15 minutes later, when the Airbus A330 was scheduled to be over the Canary Islands - where the radio would generally function better, because the plane is over land - Flight 447 was expected to send a location report but didn't, Hansman said.
"You don't know that you lost contact until it didn't make its position report," he said, but "missing one position report is not that big a concern. When it didn't check in over the Canary Islands ... that's when they realized something was seriously wrong."
Filed under: 360° Radar
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