Perth, Apr 9 (AP) - Searchers looking for the missing Malaysia Airlines plane have discovered new signals consistent with those emitted by so-called black boxes in the Indian Ocean, but they do not want to send a submersible down yet to look for the plane. For now, they will continue to use the towed pinger locator to get a better fix on the location. Here's why:
THE TOWED PINGER LOCATOR
The Australian Navy vessel Ocean Shield picked up the signals using a U.S. Navy device called a towed pinger locator. It's essentially a long cable with a listening device, or hydrophone, attached to the end. It's pulled behind the boat at a depth of 3 kilometers (1.9 miles).
The pinger locator is designed to detect signals at a range of 1.8 kilometers (1.2 miles), indicating it would need to be almost on top of the black boxes - the flight data and voice recorders - to detect them if they were on the ocean floor, which is 4.5 kilometers (3 miles) under the surface. However, the latest detections indicate the pinger locator may be effective at a longer range than designed.
The first signal from the black boxes was picked up Saturday and lasted two hours and 20 minutes before it was lost as the ship moved forward. The ship then turned around and a few hours later picked up a second signal that lasted for 13 minutes. It picked up signals twice again on Tuesday.