Sarasota, Florida -- Crews say they've found the "most promising" lead yet in the search for missing Malaysia Airlines Flight 370, and the new clue may be a signal coming from a device built by a company here in the Tampa Bay area.
An Australian ship has picked up a signal from what may be an emergency beacon called a "pinger." Pingers are attached to both of the Boeing 777's black boxes.
"As soon as it hits the water, it activates," explained Sean Tancey, a manager with Dukane Seacom, the Sarasota company that made the beacons aboard the missing jet.
"About every second, it will broadcast that signal, and that's what the search teams are looking for," Tancey said.
The pingers are designed to survive a crash and work up to four miles below the ocean surface, but their batteries is running low.
Search leader Angus Houston wanted to make one thing clear. "We haven't found the airplane yet," he said at a news conference announcing the signal detection.
But after more than a month of searching, crews have their "most promising" lead yet.
The U.S. Navy has loaned Australia an underwater detector that's about three feet across and looks like a bright yellow stingray.
As it was being towed behind a ship in the Indian Ocean, the detector picked up a signal that's consistent with the pinger.
"Two separate signal detections have occurred within the northern part of the defined search area," Houston said. "The first detection was held for approximately two hours and 20 minutes."
A second detection went on for 13 minutes. That signal is consistent with one that would come from a flight recorder, but confirming that could take days and time is running out.
The battery is required to last 30 days after a crash, which is Monday, April 7. But the head of the Sarasota company that made the beacon says it could go 33 to 35 days before it starts to fade.
Dukane Seacom's president says the beacon should be at full strength only until this Saturday, at the latest.
Plus, search crews can't just follow the signal right back to its source.
"Unlike in air, where sound travels in a straight line, acoustic energy -- sound -- through the water is greatly affected by temperature, pressure, and salinity," said the Royal Australian Navy's Commodore Peter Leavy.
"That has the effect of attenuating -- bending, sometimes through 90 degrees -- sound waves."
Malaysian investigators working on land have also found something new. They've determined Flight 370 flew around Indonesian airspace on its way to the Indian Ocean. That may have been a deliberate effort to avoid being picked up by radar on the ground.