Searchers trying a new use of satellite data

WASHINGTON — Finding the missing Malaysia Airlines plane may hinge on whether searchers can narrow down where they need to look using satellite data that is inexact and has never been used for that purpose before, search and rescue experts say.

Authorities now believe someone on board the Boeing 777 shut down part of the aircraft’s messaging system about the same time the plane with 239 people on board disappeared from civilian radar. But an Inmarsat satellite was able to automatically connect with a portion of the messaging system that remained in operation, similar to a phone call that just rings because no one is on the other end to pick it up and provide information. No location information was exchanged, but the satellite continued to identify the plane once an hour for four to five hours after it disappeared from radar screens.

Based on the hourly connections with the plane, the satellite knows at what angle to tilt its antenna to be ready to receive a message from the plane should one be sent. Using that antenna angle, along with radar data, investigators have been able to draw two vast arcs, or “corridors” — a northern one from northern Thailand through to the border of the Central Asian countries Kazakhstan and Turkmenistan, and a southern one from Indonesia to the southern Indian Ocean. The plane is believed to be somewhere along those arcs.

Air crash investigators have never used this kind of satellite data before to try to find a missing plane, but after pursing other leads it’s the best clue left.

“The people that are doing this are thinking outside the box. They’re using something that wasn’t designed to be used this way, and it seems to be working,” said William Waldock, who teaches accident investigation at the Embry-Riddle Aeronautical University in Arizona. “In terms of search and rescue, they’re probably going to have rewrite the book after this.”

Authorities generally believe the plane crashed into the ocean, although they can’t rule out the possibility that it may be on land somewhere.

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