In search for missing Malaysia Airlines MH370, 'pinger' locator best option

Written by Associated Press | Perth | Updated: Apr 10 2014, 00:12am hrs
Malaysia AirlinesAndrew Smith works on a propeller of a RAAF P-3 Orion which is searching for missing Malaysia Airlines Flight MH370, in Perth. AP
Searchers looking for the missing Malaysia Airlines MH370 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.

Also read: Malaysia Airlines MH370: More underwater pings heard in hunt for plane

MH370

A fast response craft from Australian Defence Vessel Ocean Shield tows Able Seaman Clearance Diver Matthew Johnston as he searches the ocean for debris in the search zone in the southern Indian Ocean for the missing Malaysian Airlines flight MH370 in this picture released by the Australian Defence Force April 8, 2014. A robotic search vehicle is likely to be sent deep into the Indian Ocean on Tuesday to look for wreckage of a missing Malaysian jetliner on the sea floor, as officials say the chance of finding anything on the surface has dwindled. Angus Houston, head of the Australian agency coordinating the search for Malaysia Airlines Flight MH370, said the month-long hunt was at a critical stage given the black box recorder batteries were dying - or had died. (Reuters)

The first signal from the Malaysia Airlines MH370 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.

THE SIGNALS

The Tuesday signals lasted 5 minutes and 7 minutes but they were weaker, indicating that the Malaysia Airlines MH370 black boxes may be running out of battery. They have a stated shelf-life of 30 days, but sometimes they last longer. The plane disappeared just over a month ago, on March 8. The signals have given searchers a better idea of the location of the devices, which are now believed to be within a roughly 20-kilometer (12-mile) radius. Still, that is a 1,300-square -kilometer (500-square-mile) plot of the ocean floor, an area as wide as a large city.

WHY NOT SEND AN UNDERWATER CRAFT NOW

When crews determine the best possible location, the next step will be to send down the U.S. Navy's autonomous underwater vehicle Bluefin 21, an unmanned submersible that can create a sonar map of the seafloor and any wreckage, as well as take photos.

But the sonar can scan only about 100 meters (330 feet). As for its ability to take photos, it can see with lights and cameras only a few meters away in a landscape that is completely dark.

So, even after the search area has been narrowed down, deploying the underwater vehicle now to find the black boxes would be the equivalent of looking for an object the size of a desktop computer in a city the size of Los Angeles.

Indeed, the Bluefin 21 would take six times longer to cover the same area than the towed pinger locator.

So it makes more sense to use the towed pinger locator to zero in on the location of the pinger, or at least try until searchers become certain the batteries of the black boxes are dead and are no longer emitting any signals. Then searchers would have no option but to use the Bluefin 21.

CAN A CONVENTIONAL SUBMARINE NOT HELP

No. Militaries will not disclose the depth to which their submarines will go down because it is classified information. But it is believed some of the most sophisticated nuclear powered submarines can dive only a few hundred meters (yards) down.

MH370

Able Seaman Clearance Divers Matthew Johnston and Michael Arnold embarked on Australian Defence Vessel Ocean Shield, scan the water for debris in the search zone in the southern Indian Ocean for the missing Malaysian Airlines flight MH370 in this picture released by the Australian Defence Force April 8, 2014. A robotic search vehicle is likely to be sent deep into the Indian Ocean on Tuesday to look for wreckage of a missing Malaysian jetliner on the sea floor, as officials say the chance of finding anything on the surface has dwindled. Angus Houston, head of the Australian agency coordinating the search for Malaysia Airlines Flight MH370, said the month-long hunt was at a critical stage given the black box recorder batteries were dying - or had died. (Reuters)