Leaked document reveals banging heard by plane as hunt for missing Titanic tourist sub continues

A leaked memo, as seen by Rolling Stone, indicates a banging sound has been picked up by a Canadian Aircraft taking part in the search and rescue mission for the five missing aboard the Titanic tourist submarine.

The plane, armed with specialist sonobuoys to pic up sounds with sonar, picked up the noise not far from the last known position of the vanished submarine, according to a Department of Homeland Security email seen by the publication.

"RCC Halifax launched a P8, Poseidon, which has underwater detection capabilities from the air reported a contact in a position close to the distress position," the Department of Homeland Security email stated.

"The P8 heard banging sounds in the area every 30 minutes. Four hours later additional sonar was deployed and banging was still heard."

The timing or cause of the banging sound has not been revealed in the leaked document.

The leaked memo also claimed that 'the Joint Rescue Coordination Centre is working to find an underwater remote-operated vehicle through partner organizations to possibly assist' in determining the source of the noise.

A second search team also heard sounds made up of members from the travel and research group, the Explorers Society.

In another email, also seen by Rolling Stone, sounds of a 'tapping' noise were apparently heard by their crew.

"It is being reported that at 2 am. local time on site that sonar detected potential ‘tapping sounds’ at the location, implying crew may be alive and signaling," the email read.

There are a total of five souls missing on board the lost submersible.

Those missing, include OceanGate CEO Stockton Rush, Hamish Harding, Paul-Henry Nargeolet, Shahzada Dawood and his son Sulaiman.

The vessel vanished during its descent on Sunday (June 18) while en route to the Titanic wreckage and has not been seen since.

In an update, the US Coast Guard said that despite the enormous amount of resources put into the mission, 'to date, search efforts have not yielded any results'.

Speaking about the operation, Captain Jamie Frederick, of the First Coast Guard District, said it was 'complex' and 'requires multiple agencies'.

He explained that the Titan vessel now had just less than 40 hours of oxygen left for the five passengers, with the sub able to remain underwater for 96 hours.

Since the rescue mission began, the Coast Guard and other services have been searching an incredible '7,600 square miles, an area larger than state of Connecticut'.