'Gallows humor' and 'mood swings': Ex-Navy psychologist describes likely experience on missing Titanic sub

Uncertainty, panic and the need to conserve oxygen are all part of what five travelers aboard the missing Titanic submersible are likely having to manage as they wait for rescue, a former Navy psychologist told Fox News.

"Certainly there is sheer panic where their heart is racing and they're having trouble breathing … or they feel like they are going to lose their mind," said licensed clinical psychologist Dr. Justin D'Arienzo. "And certainly in a cramped space that is dark, like this situation, that can be exponentially worse."

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The ongoing search for the missing submersible used to take tourists to see the wreckage of the Titanic has covered an area "larger than the state of Connecticut" but hasn't found any signs of the vessel, said Capt. Jamie Fredrick, U.S. Coast Guard First District response coordinator, during a Tuesday press conference. The five-person submersible was reported overdue Sunday night 435 miles south of St. John's, Newfoundland.

"I think they are probably moving in and out of phases of panic, to gallows humor, to fear, to feeling really bonded with the other passengers that are with them. There's just lots of significant mood swings," said D'Arienzo.

"Psychologically, what is the killer for people in terms of maintaining calmness is dealing with uncertainty," D'Arienzo added. "It's really important to be able to surrender to that lack of uncertainty and just focus on what you have control of."

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"What those people have in control of on that submarine is remaining calm and getting to know each other," he continued. "But also trying not to talk too much, so they're not using up any oxygen."

The submersible tour, led through OceanGate Expeditions, is advertised to have enough life support to keep five people alive for 96 hours, according to the OceanGate website. The Coast Guard said during the Tuesday press conference that there is about 41 hours left of breathable air onboard the Titan.

"The submarine captain is probably trying to keep everyone calm," D'Arienzo told Fox News. "Because your muscles are energized when you're in panic, and then you are using more oxygen."

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D'Arienzo said managing a crisis on a civilian sub is much different than on a Navy submarine where sailors are ready for anything.

"Here on a civilian tour … they are not submariners. They're not all trained," D'Arienzo said.

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One of Pakistan's richest men, Shahzada Dawood, his son, Sulaiman Dawood, and the United Kingdom's Hamish Harding are among the passengers confirmed on board the Titan. And just prior to the press conference, an OceanGate spokesperson told Fox News that the company's CEO, Stockton Rush, is among the five people who are now missing.

"It is most difficult for the family that is waiting to hear news," D'Arienzo said. "I'm hoping that we're going to be rejoicing the rescue of the submarine."

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The families should "stick together and focus on what you can control as you're waiting to hear the news and, of course, trust the professionals," he said. "These people are heroes. They find a needle in a haystack. You got to trust that there's going to be good news."

To watch D'Arienzo's full interview, click here.

Greg Norman contributed to this report.