Diver fatality during subsea lifting operations – update

This is the second safety alert concerning the fatal diving incident initially drawn to members’ attention in IMCA SF 19/18 Diver fatality during subsea lifting operations.  This update specifically relates to the use of the secondary life support (SLS) system.

What happened?

During the removal of a spool at 172msw, divers were engaged in lift bag operations to relocate the spool to a wet store location.  During the operation, a series of events occurred which resulted in one end of the spool rising off the seabed.  The umbilical of one of the divers was caught in the lift bag rigging, causing the diver to ascend with the spool until the spool’s ascent was arrested.

Following the descent of the spool back to the seabed, the diver’s umbilical was trapped between the spool and a seabed structure resulting in the loss of the diver’s primary breathing gas supply.

What went wrong?  What were the causes?

The diver’s secondary life support (SLS) system was activated, however, there was a delay between the two actions required to fully activate the SLS system.  The interface valve on the diver’s helmet (step 1) was activated by the diver, however, the delay in the diver pulling the actuation handle on the harness (step 2) to deploy the counter lungs resulted in the system becoming an open circuit.  This delay caused the diver’s SLS breathing gas to deplete much more quickly than in the event of immediate and full activation. 

The SLS unit was inspected and functionally tested by the equipment manufacturer immediately after the incident which was found to be working within the manufacturer’s parameters with no identifiable defects.

What actions were taken?  What lessons were learned?

Divers have been refreshed in the use of emergency equipment including the SLS system and frequent training and drills have been implemented.

The continued use of the two-stage activation SLS system has been evaluated and a decision has been made to replace the current two-stage SLS systems with single-stage activation systems.

The use of heavy duty cold water neoprene gloves (reduced dexterity) and the diver’s personal equipment (tooling) on his harness may have hindered the diver’s activation of the SLS, therefore these will be reviewed on a case by case basis.