There is a limited battery life for the beacons in the cockpit-voice and flight-data recorders — about 30 days, said Chuck Schofield, vice president of business development for Dukane Seacom Inc. He said it's "very likely" that his company made the beacons on the missing jet. The devices work to a depth of 20,000 feet, with a signal range of about 2 nautical miles, depending on variables like sea conditions. The signals are located using a device operated on the surface of the water or towed to a depth.
Experts say it is impossible to tell if the grainy satellite images of the two objects were debris from the plane. But officials have called this the best lead so far in the search that began March 8 after the plane vanished over the Gulf of Thailand on an overnight flight to Beijing.
For relatives of those aboard the plane, which went missing March 8, hope was slipping away, said Nan Jinyan, sister-in-law of passenger Yan Ling.
"I'm psychologically prepared for the worst and I know the chances of them coming back alive are extremely small," said Nan, one of dozens of relatives gathered at a Beijing hotel awaiting any word about their loved ones.
Malaysian authorities have not ruled out any possible explanation for what happened to the jet but have said the evidence so far suggests it was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next.
Police are considering the possibilities of hijacking, sabotage, terrorism or issues related to the mental health of the pilots or anyone else on board.
The Associated Press contributed to this report.