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The increasingly desperate attempts to recover flight MH370’s black box before its battery runs out ramped up on Friday morning as the U.S. Navy deployed a “high tech ‘black box’ locator” for the first time. The Towed Pinger Locator, as it is known, will be towed behind a navy ship covering a 150 mile track, and will be joined by a British hydrographic vessel.14 planes and nine ships are currently searching a large oceanic area northwest of Perth, Australia.

Monday will mark 30 days since the plane’s disappearance, and that milestone also marks the approximate life of the black box’s battery. That battery is important because the box sends pings while underwater, but can obviously only ping when it has a power source.

According to the U.S. Navy, a Towed Pinger Locator—no more than two and a half to three feet wide—can respond to pings coming from as low as 20,000 feet below the surface. “The Pinger Locator is towed behind a vessel at slow speeds … The received acoustic signal of the pinger is transmitted up the cable and is presented audibly … The operator monitors the greatest signal strength and records the navigation coordinates. This procedure is repeated on multiple track lines until the final position is triangulated.”

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