Missing Titanic sub: what are submersibles, how do they communicate, and what may have gone wrong?

• An extensive search and rescue operation is underway to locate a commercial submersible that went missing during a dive to the Titanic shipwreck.
• According to the US Coast Guard, contact with the submersible was lost about one hour and 45 minutes into the dive, with five people onboard.
• The Titanic’s wreck sits some 3,800 metres deep in the Atlantic, about 700km south of St John’s, Newfoundland.

OceanGate’s Titan submersible goes missing

• Unlike submarines, they usually have a viewport to allow passengers look outside, and outside cameras that provide a broader view around the submersible.
• The missing submersible in question is an OceanGate Titan watercraft, which can take five people to depths of up to 4,000m.
• The Titan is about 22 feet in length, with speeds of about 3 knots, or 5.5km per hour.

Communication and rescue efforts

• Given it has lost all contact with its surface vessel, it may have suffered a power failure.
• According to reports, at least two aircraft, a submarine and sonar buoys were being used to search for the vessel.
• One of the major challenges in the rescue effort will be contending with weather conditions, which will further shrink an already narrow search window.

What might have happened?

• For instance, it may be equipped with additional weights that can be dropped to instantly increase its buoyancy and bring it back to the surface.
• Alternatively, the vessel may have lost power and ended up at the bottom of the ocean.
• The worst case scenario is that it has suffered a catastrophic failure to its pressure housing.
• Read more:
  Indonesian submarine found: what might have happened to the KRI Nanggala in its final moments?