Approaching supersonic speed, the jet reared up at 16,000 feet and climbed to 24,000 feet, then dove again and broke apart when it was at about 10,000 feet. The data recorder on the downed jet is a sophisticated model that records as many as 74 flight measurements. Although their location is known, retrieving the boxes in turbulent seas has not been successful. The boxes' pingers, which identify their location under water, have been so loud at times that drone operators have had to remove their headsets, Navy Capt. Bert Marsh said.
Officials say they are apparently buried beneath silt or crash debris.
The robot Magnum is larger and better protected against the high seas that forced the USS Grapple with its robot, Deep Drone, to return to port Sunday. The civilian ship that carries the Magnum, the Carolyn Chouest, is also better able to handle the seas. It can essentially hover over a spot without anchoring. Investigators say they have identified two wreckage fields on the sea floor.