The Malaysian Insider
March 19, 2014

After 12 days and more than 200 hours, the search for the missing Malaysia Airlines flight MH370 jetliner has become a race against time for investigators trying to locate the aircraft’s black box.

ABC News reported that there are only 18 days left for the search teams to locate the most important piece of aviation technology, as it will only transmit a signal for 30 days.

The report said the black box has lost a third of its battery life since the plane disappeared on March 8 with 239 people, including 12 crew members, on board.

It will be a daunting task for the search teams to locate the black box before the battery runs out as they scour a search area of 2.24 million square nautical miles, said the American news company.

ABC News said if a plane crashes into the water, an underwater locator beacon sends out an ultrasonic pulse that cannot be heard by human ears but can be detected by sonar and acoustic-locating equipment.

There is a submergence sensor on the side of the beacon, and when this sensor touches water the beacon activates.

The beacon then sends out pulses at 37.5 kilohertz (kHz) and can transmit sound as deep as 4,267 metres.

Once the beacon begins “pinging,” it pings once per second for 30 days. In rare and severe crash instances, the beacon may get snapped off during a high-impact collision, the report said.

Search teams must be about 25 kilometres in range of the beacon to locate it. Underwater terrain such as deep trenches could also affect detection of the beacon’s signal, it added. – March 19, 2014.