Three days have already passed since the small submarine Titan dived, on the morning of June 18, towards the wreck of the Titanic. The five passengers on board have 70 to 96 hours of oxygen. Knowing that every hour counts, the US Coast Guard is actively searching, but finding the small submersible from the private company OceanGate proves to be particularly complex. Lost in the North Atlantic, 700 kilometers south of Saint-Jean-de-Terre-Neuve, it is located in a “remote region” which is a “challenge” for research, said American Admiral John Mauger .
Missing submarine: Search near Titanic ‘didn’t yield any results’, approximately 40 hours of oxygen remaining
The exceptional depth to which the Titan plunged, 4000 meters to the seabed, is also a challenge. “A submarine experiences a pressure equivalent to 1 kg every 10 meters”, explains Alexis Rosenfeld. The experienced diver, who connects military and civilian expeditions in the oceans, explains that the pressure at the level of the wreck of the Titanic reaches 380 bars… or more than 380 kg of pressure per cm2. “I let you imagine the force exerted on the Titan”. Less than a dozen machines in the world – including Ifremer’s Nautile – are capable of reaching such a depth.
Three hypotheses exist. Or the submarine has imploded, because the slightest incident, at such a depth, is fatal. In this case, the crew has no chance of having survived. Second option, he was trapped in the wreckage of the Titanic where he got stuck. This situation would make sonar searches very uncertain, because “for sonar to work, either the device would have to keep moving, or it would not be embedded in the mud on the bottom, or obscured by a rock or the wreck itself”, explains to Le Figaro an engineer officer of the French Navy. “We are not immune to mapping the place where it is and to pass by”.
Last possibility, he may have simply, because of the weather for example, lost contact with the escort ship that remained on the surface, supposed to inform him of his location. But this last hypothesis seems unlikely in the eyes of the experts, insofar as a submarine has multiple means of communication. Thus, this officer estimates at “less than 1%” the possibility that the Titan is still between two waters, “80% that it is on the ground, and 20% on the surface”.
“If he’s sunk to the bottom of the sea and can’t come back up on his own, the options are very limited. Very few ships can go that far, and certainly not divers,” said Alistair Greig, professor of marine engineering at University College London, pessimistically. Either way, the US Coast Guard said it is working with military and civilian partners on a rescue plan if the ship is found underwater. But the possible intervention options are extremely limited.
When a submarine is less than 180 meters from the surface, the “individual sassement” method is generally used. The crew took refuge in a watertight airlock, equipped with water and food supplies. Each member puts on a floating suit, which allows them to float for several hours on the surface of the water while limiting the risk of hypothermia for 24 hours. The airlock fills with water at ambient pressure and, once the pressure is balanced with the outside, it is opened to allow the ascent to the surface, which is done very quickly.
Except that the Titan, a tiny tourist machine, does not have this kind of equipment specific to military aircraft. Its possible rescue equipment is not indicated on the technical sheet available on the OceanGate website. “In theory, the backup means for this type of device is a localization buoy, which releases itself, rises to the surface and positions the submarine, using a coil of very resistant cable”, explains Alexis Rosenfeld.
At this point, the most credible means of rescue for the Titan appears to be, in the eyes of the experts, refloating. The operation consists of hanging air buoys on the device to bring it to the surface, via a remotely operated robot (ROV). These robots are able to reach a very great depth. In France, for example, the Victor 6000 can go up to 6000 meters. “But we have very few industrial means capable of compressing air to pressures beyond 400 bars, as well as towing them in the area”, explains the engineer of the French Navy, judging any bailout operation very complicated.
Other techniques exist: the ventilation method, the very first technique to assist a submarine in distress. Operational since 2010, it is done using an atmospheric spacesuit called NewtSuit, which operates up to 300 meters deep. “The spacesuit is piloted by a man who comes to camp air sleeves to bring in fresh air and evacuate the stale air from the submarine. It is thus ventilated while awaiting rescue,” explains Alexis Rosenfeld.
But the most complete means of rescue to date remains the NSRS system, set up by NATO after the “Kursk” disaster. During this tragedy on August 12, 2000, 118 sailors died at a depth of 108 meters. Since then, international coordination between France, Norway and the United Kingdom has set up the Nato Submarine Rescue System (NSRS), operational up to 600 meters deep.
The process is as follows: the submarine, prepared by a remotely operated intervention robot, joins the device in distress. It stows its own airlock to the submarine’s rescue airlock if it has one – which is the case for all military submarines. It then rises to the surface, winched onto the deck of the ship housing the entire rescue system (which must have a deck of at least 400 m²).
“The solutions exist, but the question is rather to know: what measures, including military ones, would we be ready to implement for a group of tourists?” Asks Alexis Rosenfeld. The NSRS system, based in Faslane, Scotland, is air transportable, but heavy and bulky. It is theoretically deployable anywhere in the world in 72 hours, except in spaces covered with ice.
Such a rescue operation would be, by far, the maneuver carried out in the greatest depths of history. The last record dates back to 1973, when the Canadian commercial submersible Pisces III became trapped on the seabed and was recovered after 76 hours under the Celtic Sea, off Ireland. But it was only 1575 feet deep, or about 480 meters… The two people on board had been rescued 12 minutes before running out of air. “One thing is certain, concludes Alexis Rosenfeld, Paul-Henri Nargeolet (who is on board, editor’s note) is one of the best submarine experts in the world. He knows the rescue procedures very well, and no solution will be overlooked.”
