BEIJING — The pinger locater that Chinese searchers are using in the quest for Malaysia Flight 370 is a $16,000, U.S.-made device typically used by divers to find lost marine equipment in relatively shallow waters. But the Massachusetts manufacturer says it’s possible the machine could detect pulses from an airplane “black box” lost in the ocean several miles deep.
Thomas Altshuler, vice president and group general manager of Teledyne Marine Systems, said his company was aware that China had purchased several of its pinger locaters in the past but did not know how or where authorities were using the equipment.
On Saturday, China’s state-run media said crews with the patrol ship Haixun 01 had briefly picked up 37.5 mHz pulses — the same frequency as emitted by an airplane flight data recorder pinger — on Friday and Saturday in the Indian Ocean, at a latitude of 25 degrees south and longitude of 101 degrees east. Photos of the crew showed them using Teledyne Benthos equipment.
The pinger locater the crew was using is designed for divers to search at depths up to 600 feet; in this case, it had an adapter that allows it to be hung it off the side of a boat. But the depth rating relates more to the pressure the housing can withstand, Altshuler said, rather than the distance at which pings could be detected.
Australian officials said Sunday ocean depths in the area where the Chinese crews reported detecting the pulses could be up to 4,500 meters, or about 14,700 feet.
“It would typically not be used to be look for something that is thousands of meters deep in the ocean. That’s not what it is designed to do,” Altshuler said in a phone interview. “But it is possible to detect at this depth. … The physics would say that it is possible.”
Altshuler said he had asked a pair of his firm’s scientists to calculate the equipment’s capabilities under such conditions.
Until late Saturday, Australian authorities coordinating the search for Flight 370, which disappeared March 8 on a flight from Kuala Lumpur to Beijing, had indicated that only two ships in the search fleet – the Australian vessel Ocean Shield and the British survey ship Echo – had carried equipment that could detect transmissions from an airplane black box. In the case of the Ocean Shield, it is towing a deep-water pinger locater lent by the U.S. Navy that Altshuler said is designed to work at depths of 6,000 meters, or nearly 20,000 feet.
Teledyne Benthos is one of two manufacturers of black box pingers, which are built to FAA specifications; the other is Dukane Seacom. But similar pingers that emit different frequencies are attached to many other types of marine equipment to make it easier to locate if they become lost.
Australian Air Chief Marshal Angus Houston, who is coordinating the search from Perth, said Sunday that the Echo was headed to meet up with Haixun 01 to see whether it could substantiate the Chinese crew’s findings.
The crew of the Ocean Shield – which was some 300 nautical miles away from Haixun’s location – on Sunday said they too had detected an “acoustic event” in their area possibly related to Flight 370’s black box. The ship was staying in that vicinity for the time being to investigate further.
Altshuler said while the Teledyne Benthos equipment can detect pings, it does not record them and save them for later, unless the device had been modified by the Chinese.
Chinese searchers reported detecting the 37.5-mHz pulses for only two brief periods; in one case, the pulses lasted about 90 seconds. Houston cautioned at a news briefing Sunday that these were “fleeting” acoustic events and not a continuous signal as one might expect if it were coming from a black box.
However, Altshuler said the pinger detector employs a cone-shaped listening device, so slight movements of the cone in any direction may cause the detector to lose a signal. Other factors might also account for a spotty detection.
“The physics of how sound propagates through the water is very complex,” he said. “Like with a cellphone, you walk around your house and the signal fades in and out. …. There’s an analogous effect in the ocean.”
The challenging search for Flight 370, Altshuler said, points up the fact that airplane black boxes carry only very basic technology, even though much more advanced equipment that could make such searches less difficult is available today.
For instance, he said, aviation authorities could mandate that black box pingers carry 90-day batteries, instead of the 30-day ones that are standard now. Or, he said, they could be equipped with transponders, which don’t emit a signal until they are “engaged” by a detection device that sends out a search signal. Such transponders, he noted, can have a battery life of several years.
“I don’t know why government or policy is done the way it is,” he said. “There is technology that is readily available that could make the search of something like this easier — from the top side and what’s on the [airplane].”
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