For the latest updates on the search for the missing submersible, head here.
Rescue teams involved in the hunt to locate the submersible housing five tourists that had planned to visit the wrecked Titanic transatlantic liner said "noises" had been detected early Wednesday close to where the sub ended contact with its mother ship.
The U.S. Coast Guard said that a maritime surveillance plane operated by Canada detected the noises, which experts from the U.S. Navy are now analyzing.
U.S. authorities said various underwater search efforts had been moved to the location of the noise to discover its source, but that so far, the underwater drones operated remotely had "yielded negative results."
The U.S. Coast Guard also tweeted early Wednesday that the data from the Canadian aircraft, a known as a P-3 Orion, would nevertheless potentially form part of future search plans once it had been analyzed.
The submersible, called Titan, had five passengers on board when it lost contact with its support ship - a Canadian research vessel called Polar Prince - less than two hours after it first entered the water on Sunday. At that point it was already more than halfway down to the Titanic's wreck on the Atlantic's ocean bed, roughly 900 miles east of Cape Cod in Massachusetts.
Experts involved in the search and with knowledge of the submersible's technology say that the oxygen on board is likely to last only until early Thursday morning, and the remoteness of the location and extent of the possible search area, larger than Connecticut, has complicated efforts to locate the vessel and its passengers.
"It takes time, and it takes coordination," said U.S. Coast Guard captain Jamie Frederick at a news conference in Boston. Commercial vessels have joined the effort since Sunday, and the French Navy has also redirected one its ships to the site.
Those on board include Stockton Rush, the head of OceanGate, the company that developed the submersible; Paul-Henri Nargeolet, a French underwater wreck expert who has written about the Titanic and visited the wreck dozens of times; a British entrepreneur Hamish Harding and father-son Pakistani nationals Shahzada and Suleman Dawood.
The design of the submersible means that only those outside the vessel can unseal it, so regardless of whether it rises to the surface or not the passengers will require outside help to escape.
