Missing jet: Indian Ocean 'pings' last, best hope for Flight MH370?

A Chinese search ship has reported electronic signals from the area where the Malaysia Airlines missing jet is thought to have gone down. They’re the same frequency as the ‘black boxes.’

Nearly a month after Malaysia Airlines Flight MH370 disappeared into a seeming void of false reports, tantalizing speculation, and conspiracy theories, searchers report what could be the best evidence yet of the disappeared Boeing 777 and the 239 people aboard.

On Friday and again on Saturday, a Chinese ship detected 90-second electronic signals in the search zone.

China's official Xinhua News Agency reported that a patrol vessel had detected a "pulse signal" in the southern Indian Ocean at 37.5 kilohertz. That’s the same frequency emitted by the flight data recorders – the so-called “black boxes” – aboard the missing plane.

Then on Sunday, an Australian ship carrying sophisticated deep-sea sound equipment picked up a third signal in a different part of the massive search area.

Two major challenges indicate a race against time: The search area is vast – 84,000 square miles – and the batteries on the flight data recorder and the cockpit voice recorder are likely to run out in the next few days. Once they go silent, the challenge in finding this crucial evidence of what happened March 8 becomes infinitely greater.

"This is an important and encouraging lead, but one which I urge you to treat carefully," retired Australian Air Chief Marshall Angus Houston, who is coordinating the search, told reporters in Perth.

"We are dealing with very deep water, we are dealing with an environment where sometimes you can get false indications," Houston said. "There are lots of noises in the ocean, and sometimes the acoustic equipment can rebound, echo if you like."

Also, dragging the pinger locator on the Australian ship must be done at very slow speed given the depth of the ocean in the search area – upwards of five miles down.

Airline technology consultant Michael Planey says with no other clues found, searchers would have to have "astronomical luck" to be led to the black boxes with just this kind of signal.

"I hate to say at this point that anything is a significant announcement,” Mr. Planey told CBC News Saturday. “We've been down so many blind paths and wrong alleys and everything in the search and what's been reported that I don't want to be overly hopeful.”

"It would be truly incredible luck to blindly stumble across the ping from the black box, with no other debris having been located, with no other clues that this could be from that missing Malaysian aircraft," he said. “"The reality is, the frequency that [the Chinese ship] detected is the same frequency that is used in almost all emergency locator pingers and in a number of other sea-going devices. So it could be attached to another random piece of equipment that has fallen off of a cargo ship.”

In addition to the electronic signals, the Xinhua news agency also said a Chinese air force plane had spotted a number of white floating objects in the search area. This has happened several times in recent weeks as satellite photos show what appear to be objects in the water; none of them has panned out.

The Australian Maritime Safety Authority reported Sunday, that up to 10 military aircraft, two civilian planes and 13 ships were taking part in the search for debris or any sign of the jet.

The missing Boeing 777 disappeared March 8 while en route from Kuala Lumpur to Beijing.

In Kuala Lumpur, families of passengers aboard the missing plane attended a prayer service on Sunday that also drew thousands of Malaysian sympathizers.

"This is not a prayer for the dead because we have not found bodies. This is a prayer for blessings and that the plane will be found," said Liow Tiong Lai, the president of the government coalition party that organized the two-hour session.

This report includes material from the Associated Press.