Titanic director James Cameron said he predicted Titan's implosion days before the debris from the missing submersible was found, calling the search a 'prolonged nightmarish charade'.
But officials say the men were likely to have died on Sunday – before military planes using sonar buoys detected what they thought could have been SOS 'banging' sounds in the water. The US Navy said they heard a sound consistent with an implosion after communications were lost around two hours into their journey. The Navy passed on that information to the Coast Guard, an insider said.
Mr Cameron told BBC News that the search 'felt like a prolonged and nightmarish charade where people are running around talking about banging noises and talking about oxygen and all this other stuff'.
'I knew that sub was sitting exactly underneath its last known depth and position. That's exactly where they found it,' he said.
Mr Cameron said: 'I felt in my bones what had happened. I immediately got on the phone to some of my contacts in the deep submersible community. Within about an hour I had the following facts. They were on descent. They were at 3500 metres, heading for the bottom at 3800 metres.
'For the sub's electronics to fail and its communication system to fail, and its tracking transponder to fail simultaneously – sub's gone
'The implosion would have generated a significant, broadband sound that the sonar buoys would have picked up,' explained Rear Admiral John Mauger of the US Coast Guard at a press conference.
A Canadian Navy ship carrying medics specialising in treating health issues relating to deep-sea diving arrived on the scene this morning on the HMCS Glace Bay. They also brought a hyperbaric chamber – which can be used for decompressing divers after they return to the surface.
Above the wreck was flotilla of at least ten ships, two robot subs and several aircraft scanning the Atlantic for any sign of Titan as sonar continued to hear a banging noise from the depths. A Royal Navy submariner, as well as equipment from a British company, was also sent to assist in the search.
As recently as Wednesday afternoon, Coast Guard response coordinator Captain Jamie Frederick for First Coast Guard District said: 'This is a search and rescue mission, 100 per cent.'
The U.S. Navy likely heard the sound of the Titanic tourist submersible imploding shortly after it was reported missing, according to a report - and yet still a massive international rescue effort was launched hoping to find survivors alive.
The Navy maintains an acoustic detection system around its coast for early detection of enemy submarines, and has done since the 1950s.
The U.S. Navy conducted an analysis of acoustic data and detected an anomaly consistent with an implosion or explosion in the general vicinity of where the Titan submersible was operating when communications were lost,' a senior U.S. Navy official told The Wall Street Journal in a statement.
'While not definitive, this information was immediately shared with the Incident Commander to assist with the ongoing search and rescue mission.'
The sound was detected in an area where the debris from the sub was located on Thursday. Hours after the debris was found, officials noted the five people on board were presumed dead in an implosion.
The implosion was not detected by sonar buoys used by search crews, he said, which suggests it happened before they arrived - and was indeed heard by the U.S. Navy.
'We had listening devices in the water throughout and did not hear any signs of catastrophic failure from those,' said Mauger.
'The implosion would have generated a significant, broadband sound that the sonar buoys would have picked up.'
It is not known why the U.S. Navy did not make the information about the likely implosion known. It is also not known if they informed the families or rescue crews of their analysis.