21/06/2023
As we all hold out hope for the recovery of the Titan manned submersible and the five people aboard, I thought I'd share the story of the deepest underwater rescue - Pisces III.
On 29 August 1973 Roger Mallinson and Roger Chapman began their dive aboard Pisces III. They were in the Celtic Sea, south of Ireland, laying a new transatlantic cable.
Just after 9am, as they were preparing to be hauled back onto their support ship, their tow line tangled on a hatch, ripping it open. Water flooded into rear compartment, sealed off from the crew in the front. However it caused the submersible to start sinking. There was sudden jolt as Pisces III reached 175 feet, as she hung suspended by a single rope.
The cable would not hold for long. Pisces III was much heavier than she should have been now one of her compartments was flooded. She was also swinging back and forth in the currents, putting further strain in the rope. It was a matter of time before the cable snapped and she began to plummet to the bottom.
The submersible hit the sea bed at around 40mph, raising concerns of further damage to the vessel. But she was structurally secure and her oxygen supply and carbon monoxide filter systems were operational. She lay on her side and the crew sat in darkness, waiting for rescue.
An international effort to save the men commenced. Submersibles Pisces II and Pisces V were flown to Ireland. The US Navy volunteered an unmanned rescue vehicle (CURV-III), the Canadian Coastguard sent a ship that happened to be in the vicinity, and the Royal Navy sent a specialist deep sea vessel.
It was nearly two days since the accident before everything arrived and rescue attempts could begin. Pisces II and V made several failed attempts over the following day.
On 1 Sept, with time running out, Pisces II found the stricken submersible and managed to attach a line to it. CURV-III then arrived with a second line. At 10.50am, more than three days after Pisces III hit the seabed, she started to lift towards the surface. When divers finally managed to open the hatch and release the crew the oxygen cylinder was down to only 12 minutes remaining.
Everyone hopes for the same good fortune for the Titan crew, but it should be noted that if they've found themselves on the seabed near Titanic, they are nearly eight times deeper than Pisces III.