寻找失踪客机考验各国技术极限

choi

Keith Bradsher, 寻找失踪客机考验各国技术极限. 纽约时报中文网, Apr 8, 2014
cn.nytimes.com/asia-pacific/20140408/c08search/

, which is translated from

Keith Bradsher, Hunt for Malaysian Jet Tests Technical Limits; Pingers offer hints of hope of obstacles. New York Times, Apr 8, 2014.

Excerpt in the window of print: A task that is both short on time and 'right on the edge of capability.'

Quote:

"But the estimated depth, nearly 15,000 feet, is already at the very limit of the submersible’s [NOT that of a submarine, whose dive is more shallow] certified range.

"The towed pinger locator [supplied by US and carried on the Australian ship Ocean Shield, which is donated by a private Norway company after retirement], essentially a powerful set of microphones towed through the depths at the end of several miles of cable, is operating in the undersea equivalent of an echo canyon. Differences in water pressure, salinity and temperature can send noises ricocheting in unpredictable ways, unlike the fairly straight lines along which sounds are usually transmitted in the air. 'That has the effect of attenuating, bending — sometimes through 90 degrees — sound waves,' said Commodore Peter Leavy of the Royal Australian Navy, who is helping to lead the search.

"“the towed pinger locator moves at no more than 3 knots, or 3.5 miles per hour, and covers a two-mile-wide swath as it does so, for just seven square miles [3.5  times 2] in an hour.

"The United States has a policy of not disclosing the locations of its submarines. The United States Navy does not disclose the maximum operating depth for its attack submarines and ballistic missile submarines, as opposed to deep-sea research submarines, but says on its website that they can dive to at least 800 feet.

"China announced on Saturday that one of its vessels, the Haixun 01, had detected pings. But China’s method for searching, in which sailors hold a marine listening device over the side of the boat, drew skepticism from oceanographers and other search experts, especially as the Chinese vessel was 375 miles away from where the Ocean Shield twice identified frequent pings.

My comment:
(a) The last quotation (the only mention of China in this report) offers yet another inexperience of China's crew, other than the fact the listening device is designed for divers which can not resist pressure when lowered further than human limits. A sound locator has to be away, away from the engine and propeller of the ship.
(b) There is no need to read the rest.