Specialist engineers were beginning an inquiry on Thursday into how a crane fell onto the deck of an aircraft carrier injuring several sailors.
The crane was trying to lift a cherry picker when the accident happened
The crane driver was also hurt when he was trapped in his cab for 90 minutes after it toppled onto the deck of HMS Invincible in Portsmouth harbour.
He remains in hospital with a head injury following Tuesday's accident.
Four sailors suffered minor injuries, two of whom jumped overboard, and 12 other naval staff sustained cuts.
Engineers from the Health and Safety Executive are carrying out the investigation, which comes three weeks after the crane underwent an inspection, according to owners Fleet Support Limited.
The crane was attempting to pick up a cherry-picker, being used as part of refurbishment work on the ship, when the accident happened.
HMS Invincible, which carries Sea Harrier fighter planes, Harrier GR7 bombers and Sea King helicopters, returned to Portsmouth last year following a £64m refit.
It was in the navy base for routine maintenance work and its deck has scaffolding on it and is covered in tarpaulin.