Subsea Spool Tie-in Incident

• During subsea spool tie-in operations, a crane hook unexpectedly struck a diver's helmet.
• The incident occurred on March 6, 2025.

What Happened

• Divers were working on the seabed in poor visibility during subsea spool tie-in operations.
• After landing the pipe handling frame (PHF), the Diving Supervisor instructed the crane operator to lower the crane hook to the seabed to allow the diver to disconnect rigging from the crane.
• The crane operator reported 'no weight' on the crane wire, so the Diving Supervisor assumed the hook had reached the seabed
• The supervisor instructed the diver to disconnect the PHF from the crane.
• The crane hook unexpectedly struck the diver's helmet when the diver was positioned beneath the PHF and moving to disconnect the rigging.
• The diver was unharmed and returned to the dive bell, and the dive was aborted.
• The diver's reclaim helmet was damaged beyond repair, including the side block, but the integrity of the helmet was maintained, and the diver was unharmed.

What Went Right

• Diver 2 promptly assisted Diver 1, ensuring no injuries were sustained, and both divers immediately returned to the bell safely.
• Both divers and the crane block had locating beacons fixed to them, enabling accurate tracking.
• All procedures, lifting plans, and Job Hazard Analyses were followed throughout the operation.
• Protective equipment worked, and the diver was uninjured because the helmet absorbed the impact.

What Went Wrong

• Lowering the crane hook for PHF rigging disconnection caused it to rest on the top beam of the PHF.
• This resulted in a 'no weight' reading, leading the crane operator to assume the hook had reached the seabed.
• The hook slipped off the beam and struck the side of the diver's helmet as the diver approached the disconnection point.

What Was the Cause

• An inadequate length of crane pennant or stinger did not provide sufficient distance between the divers and the crane hook.
• Poor visibility hindered the ability to accurately observe the crane hook position.

Lessons and Actions

• Ensure adequate distance between divers and crane hook.
• The length of the crane pennant/stinger should maintain a safe distance between the divers and crane hook during subsea operations.
• Enhanced visibility aids and monitoring:
  • Use alternative methods such as additional locating beacons, underwater cameras, or sonar in poor visibility.
• Reinforced communications:
  • Minimize assumptions regarding equipment position.
  • Reinforce clear communication and confirmation procedures between the dive supervisor, crane operator, and divers to ensure all parties are fully aware of the equipment's location.

Additional actions

• Updated project procedures to specify minimum pennant lengths for different operations.
• Conducted pre-operation inspections of all rigging and lifting equipment, including crane hooks and pennants, to ensure they meet safety standards and are appropriate for the operation.
• Updated the Job Hazard Analysis (JHA) to reflect lessons learned regarding safe distances, visibility, and communication requirements for subsea lifting operations.