US Coast Guard says underwater noises detected in search for missing submersible

INA-  sources 

The US Coast Guard has confirmed an aircraft involved in the search for a missing submersible in the North Atlantic has detected underwater noises in the search area.
Several US media outlets are reporting sonar-detected banging in 30-minute intervals, citing an internal government memo, during the search for the submersible that was on a trip to see the wreckage of the Titanic.  
The discovery on Tuesday led search teams to relocate their underwater robotic search operations "in an attempt to explore the origin of the noises," the Coast Guard said in a series of tweets early on Wednesday.
The newly relocated searches by ROV (remotely operated vehicles) came up empty handed but will continue, the Coast Guard said.
The Coast Guard did not detail the nature or extent of the sounds that were detected, or how they were picked up.
Navy.  
The Titan, operated by US-based OceanGate Expeditions, was built to stay underwater for 96 hours, according to its specifications — giving the five people aboard until Thursday morning local time before air runs out.
One pilot and four passengers were inside the miniature sub early on Sunday when it lost communication with a parent ship on the surface about an hour and 45 minutes into its two-hour dive.
US Coast Guard Captain Jamie Frederic said that US and Canadian aircraft had searched more than 7,600 square miles (19,684 square kilometres) of open sea. 

The Explorers Club, which Hamish Harding and Paul-Henri Nargeolet are members of, says it understands there are likely "signs of life". 
President of the club, which is a New York-based multidisciplinary professional society promoting scientific exploration, Richard Garriott do Cayeux said they had "greater confidence" as the search for the submersible continued. 
"We are so grateful for the US Coast Guard and other international teams and commercial operators doing everything they can to help from the Titanic expedition submersible," he said in a statement.

'All options' mobilised in search

Experts say rescuers face significant obstacles both in finding the Titan and in saving the people aboard.
In the event of a mid-dive emergency, the pilot would likely have released weights to float back to the surface, according to University College London marine engineering professor Alistair Greig.
But he said without communication, locating a van-sized submersible in the vast Atlantic could prove challenging.
The submersible is sealed with bolts from the outside, preventing the occupants from escaping without assistance even if it surfaces.
If the Titan is on the ocean floor, a rescue effort would be even more challenging.
The Titanic lies 3,810 metres underwater and only specialised equipment can reach such depths without being crushed by the massive water pressure.
"I think if it's on the seabed, there are so few submarines that are capable of going that deep. And so, therefore, I think it was going to be almost impossible to effect a sub-to-sub rescue," Titanic expert Tim Matlin said.​
OceanGate said it was "mobilizing all options".

source: ABC