Titanic: how much oxygen does Titan submersible have - what time is the air expected to run out?

US and Canadian authorities were joined by private firms in a race against time to locate and retrieve the Titan submersible, believed to be thousands of metres below the surface in the Atlantic Ocean near the wreck of the Titanic.

Passengers paid $250,000 each to travel in the extreme tourism trip which would have taken them to explore the wreck of the Titanic on the ocean floor, around 370 miles off the nearest coast.

Hopes of success for the search and rescue grew when an intermittent banging sound was recorded by sonar technology - experts believed the banging came from those inside the Titan as they attempted to make rescuers aware of their location.

But, as the hours have ticked by, chances of finding Titan with the five passengers still alive have grown slim, as desperate family members are watch on helplessly.

How much oxygen does the Titan submersible have?

The dive to the Titanic and return to the surface is supposed to take between eight to 10 hours, but the Titan has enough oxygen to last many times longer than this in case of an emergency.

The Titan is believed to have a 96-hour supply of oxygen for five people - which is equal to four full days.

However, the air supply could run out more rapidly due to several factors - for instance if the crew are breathing rapidly due to the high stress situation, this would cause the air to be used up faster.

The temperature on board Titan will also be an important factor - if the vessel has lost power, those on board are likely to be very cold as the temperature in the water outside Titan will be around 4 degrees. Shivering causes oxygen to be used up very rapidly.

However, the crew can also find ways to conserve oxygen - by meditating, sleeping, and controlling their breathing.

When will Titan’s oxygen run out?

The dive began at around 9.30am Newfoundland Daylight Time (NDT) on Sunday 18 June and was expected to resurface at 4.30pm.

No-one is sure exactly when the submersible’s oxygen supply will run out because of the range of factors that affect how quickly it is used up. 

The 96 hour supply is based on an average oxygen usage for a seated human over that time period.

On that basis, the oxygen supply is expected to run out at around 9.30am today (NDT) which is around 1pm BST.

How likely is it that the Titan submersible will be found?

Tragically, the odds of those on board Titan being saved are now very slim. They have only a few hours of oxygen remaining, according to best estimates, and finding the vessel is only the beginning of the rescue operation.

10,000 square miles of ocean have been searched so far, and Titan has still not been found. If the vessel is located, it will be very difficult to bring it to the surface.

Because of the immense depth (3,800 metres below the surface) only a few other vessels can travel that deep. Additionally, the crew will not be able to transferred to another vessel whilst underwater.

It is likely that a remotely operated underwater vehicle would be used to attach a rescue line to Titan, which would then be lifted to the surface by a large salvage ship. The crew would then need to be freed from Titan which has been bolted from the outside. 

This entire process could take a full day, and as Titan has not yet been located, it is unlikely that a successful rescue can now be carried out.