Countdown to catastrophe at St Ann's Head

Thursday 15 February

2010: Liberian-registered supertanker Sea Empress (147,000 tonnes and 274 metres long) runs aground on rocks in Mill Bay at entrance to Milford Haven en route to Texaco oil refinery. A harbour pilot is on board with 28 Russian crew and ship's master Eduard Bolgov. Full port emergency declared - shipping banned from 10 mile radius - lifeboats and helicopters sent to scene.

2200: Three tugs refloat vessel but some 2,000 tonnes of oil pours into sea through damaged tanks. Crew and salvage engineers remain on board.

Friday 16 February

Aircraft spray slicks out at sea. Conservation groups warn of ecological disaster unless oil is offloaded because of Pembrokeshire's international importance as seabird reserve. Salvage operations postponed for 24 hours because of force 8 gale forecast for Saturday night/Sunday morning.

Saturday 17 February

16.00: Sea Empress, afloat off St Ann's Head, turned 180 degrees by tugs to face storm 35-knot winds and 10ft waves.

17.30: Sudden 60mph gust catches vessel, lines to three tugs snap, damaging vessels. Tanker breaks adrift and goes aground again causing more damage. More oil spews out.

19.00: Helicopters from RN Culdrose, Cornwall, and RAF Chivenor, Devon, airlift off 26 non-essential crew. 28 men remain on board, mostly salvage engineers. Police evacuate residents from St Ann's Head amid fears of explosion from escaping fumes.

Sunday 18 February

05.00: Tanker abandoned. Helicopter lifts off remaining crew because of worsening weather.

11.15: Five salvage workers return to ship to assess damage. Engine room found to be dry. Giant Chinese tug Deyue, one of the world's most powerful, attaches tow line.

1700: Salvage crew lifted off again because of force 9 gale. Tanker abandoned for second night, attached to two tugs.

Monday 19 February

Strong winds but weather eases. A 21-man salvage crew goes back on board to prepare ship for oil transfer.

1300: Three aircraft spray slick coming from damaged starboard tanks. Chinook helicopter delivers heavy equipment.

1900: Serious setback when tanker breaks adrift in high winds and goes aground just 300 yards from headland.

2257: Salvage crew evacuated to support vessels because of grinding noises from ship and fears of structural damage.

Tuesday 20 February

Experts calculate around a third of original cargo of nearly 130,000 tonnes of oil has now poured out. But inspection shows no sign of vessel breaking up. Ten-man crew put back on board. Plans brought forward to move tanker on evening high tide to offload remaining oil.