An Australian submarine and engineering expert says there could still be hope in rescuing the five aboard the OceanGate submersive lost in the North Atlantic Ocean.
Reports say the crew have about 24 hours of oxygen left, but good news came in the form of sonar-detected 'banging' sounds underwater, rescuers said Wednesday.
The 7-metre sub lost communication just 15 minutes from the ocean floor on Monday, sparking a massive international rescue operation.
Eric Fusil, an engineering lecturer from the University of Adelaide, told The Project the clock is ticking.
"I was very concerned because that submarine is on her own in the deep. And as we know, there is now a rescue mission, but it's very close," he said.
Fusil is a passionate submarine enthusiast too, who has dedicated more than 20 years of his career to the industry.
He said it could have been an accident or a catastrophic failure.
"But we don't know just yet.
"Fortunately we heard some banging sounds - that means someone may be alive."
Fusil said it's a very small craft.
"You have barely enough space for five people on board. It's basically a tin can. And around you, it's pitch black if you've lost power."
And underwater rescue missions are extremely complicated, he added.
"When you are underwater, there is no radio, no radar, no GPS. It's even worse than finding a needle in a haystack."
But the fact that rescuers have detected banging sounds is positive.
"Having it at regular intervals means: I'm not a dolphin, I'm not a shrimp, but I'm a human being and I'm trying to get you to acknowledge that."
Friends and family have identified the five on board, according to CNN.
They are:
- Pakistani billionaire Shahzada Dawood
- Dawood's son, Sulaiman Dawood
- OceanGate CEO Stockton Rush
- British businessman Hamish Harding
- French diver Paul-Henri Nargeolet
Watch the full interview above.