on the data devices, believed to lie on the sea floor at a depth of up to 6,200 meters (19,700 feet), will cease to operate in three weeks.
The rescuers had to rely on emergency homing beacons
, fitted to the rafts and the men's survival suits, to track them down.
But what the feds now have is much better than that: cell phones that act as homing beacons
iFob uses the built-in Wi-Fi communication of Apple iPhone, iPods and PCs, and turns these devices into homing beacons
, broadcasting, or just listening, for other copies of iFob.