Missing Titanic sub: Dubai expat Harding's friend was supposed to join him but backed out due to 'safety concerns'

Another multi-millionaire adventurer, a friend of Dubai resident Hamish Harding, had planned to go on the Titanic expedition, too. In fact, he has already paid the downpayment for a seat on the same submersible — however, he later decided to back out.

Rescuers are still scouring the North Atlantic, racing against time to find OceanGate's Titan sub, which has been missing since Sunday on its way to the famous Titanic wreckage.

Though 'banging sounds' were detected underwater on the third day of the search, there has been no tangible sign of the vessel yet. Hope wanes while panic peaks — as the craft's presumed breathable oxygen supply dwindles down to the last 24 hours.

Digital marketing tycoon Chris Brown, a 61-year-old British national, revealed in a media interview that he had signed up for the expedition with his friend, Harding.

A seat on the Titanic-exploring sub reportedly costs $250,000 — and Brown said he had already paid a deposit to join the trip.

He said he had made the decision after seeing a number of red flags.

In an interview with The Sun, Brown said he had concerns after learning that the craft's would be controlled using an outdated gaming controller.

“I found out they used old scaffolding poles for the sub’s ballast — and its controls were based on computer game-style controllers," he told the newspaper.

“If you’re trying to build your own submarine you could probably use old scaffold poles. But this was a commercial craft."

Down at depths as crushing as those the Titan dove to, using GPS tracking is also not an option. Instead, the crew receives instructions from a team on the surface vessel above via a text messaging system.