During the rig move, the drilling rig mast was to be raised. It was initially lifted 30 cm (12 inches) from its horizontal position on the high derrick stand and operations stopped for 15 minutes with the mast hoisting system under tension. This was done to allow the crew to fit Blowout Preventer (BOP) lifting beams below the sub-structure. Lifting operations then re-commenced pulling 220 tons, lifting a further 60 cm (2 feet). A bang was heard and the mast fell back 90 cm (3 feet) uncontrolled, landing on and damaging the high derrick stand. The monkey board and mast were also damaged. . No personnel injury but there was major asset damage.