Titanic Explorer Says Two Likely Disaster Causes Are Survivable. One Isn't

Joe MacInnis said if the submersible had merely lost radio contact, standard protocol would be to immediately surface.

The submersible vessel that vanished during a dive to the Titanic shipwreck may have experienced one of the so-called trinity of disasters that all such expeditions seek to avoid: a hull breach, a fire or an entanglement.

The first of those outcomes isn't survivable, said Joe MacInnis, the renowned Canadian explorer and physician who has been to the Titanic site four times and is a close friend of one of the passengers aboard the missing Titan.

"A hull failure is catastrophic," Mr MacInnis, 86, said in an interview Tuesday. "There is this kind of implosion, and it's terrible."

However, the second two disasters can be managed. Crew train for fire emergencies and although challenging, all good subs have firefighting capabilities. And MacInnis has himself experienced what it's like to be trapped by the doomed passenger ship - and to break free - more than 30 years ago.