Navy Sends Locator to Find Jetliner's Black Box


The U.S. Navy is sending to Australia an underwater drone and a device to locate black boxes to help search the wreckage of Malaysian Flight 370 should the debris field be located, Pentagon officials said Monday.

The Pentagon flew a Bluefin-21 autonomous underwater vehicle and a towed pinger locator, which can identify sounds from a plane's black box, from New York to Perth, Australia, Pentagon Press Secretary Rear Adm. John Kirby said. Both will arrive Tuesday after the equipment was requested by Adm. Samuel J. Locklear, head of U.S. Pacific Command.

The Bluefin-21 is an unmanned underwater vehicle with a side-scanning sonar and what's called a multi-beam echo sounder, said Kirby. Bluefin-21 can go to depths of 14,700 feet and travel at speeds up to 4.5 knots.

"It would be useful if there is a debris field if there were underwater objects which we believed needed to be researched," he added.

The pinger locator, which was also requested by U.S. Pacific Command, is towed behind a vessel at slow speeds, generally 1-5 knots, depending on the depth. Called the TPL-25, it carries a passive listening device for detecting pingers that automatically transmit an acoustic pulse, a Navy statement said.

The TPL-25 consists of a towed fish unit that is 30 inches long and 70-pounds. This unit attaches to a cable that can search at depths up to 20,000 feet.

"The TPL is a highly sensitive listening device that is designed to home in on the black box itself," Kirby added.

The system also includes a tow cable, wing, hydraulic power unit, generator and topside control console.

"If found, the acoustic signal of the pinger is transmitted up the cable and is presented audibly, and can be output to either an oscilloscope or a signal processing computer," according to the Navy.

The system is engineered to detect a commercial aircraft pinger mounted onto the flight recorder as part of a black box.

"Basically, this super-sensitive hydrophone gets towed behind a commercial vessel very slowly and listens for black box pings," Cmdr. Chris Budde, U.S. Seventh Fleet Operations Officer, said in a written statement.

However, in this case, the TPL-25 will be towed by a Royal Australian Navy ship, the Seahorse Standard, Kirby said.

If a signal is detected, a system operator will search for the greatest signal strength and record the navigation coordinates.

"This procedure is repeated on multiple track lines until the final position is triangulated," the statement said. "Most pingers transmit every second at 37.5 kHz, although the TPL can detect any pinger transmitting between 3.5 kHz and 50 kHz at any repetition rate."

The equipment is also being sent as a result of a conversation between Defense Secretary Chuck Hagel and the Malaysian Defense Minister who specifically asked for technologies able to help with the search, Kirby said.

-- Kris Osborn can be reached at

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