The journey from Scotland to the Pembrokeshire coast had been routine up to last Thursday night. With good weather and decent visibility, the Sea Empress and its cargo of 140,000 tonnes of crude oil were on schedule to deliver at Milford Haven oil refinery.
Around 6.30pm the first radio contact with Milford Haven port Authority was made from the tanker's bridge. Using its Global Positioning System, an advanced satellite location finder, the Sea Empress would have told the port authority where she was. Information was exchanged and plans for the pilot - who would guide the tanker into port - to board were made.
According to Captain Peter Cooney, managing director of the tanker's managers, Acomarit, the pilot boarded at 7.38pm. The pilot station is some four miles beyond St Ann's Head. From there, the official sea chart directs ships along the "transit line" towards West Blockhouse Point.
Although Sea Empress's logs are now in the hands of Department of Transport investigators, the company believes the logs will show that as 8pm approached, the ship was steaming west of the transit line.
Low tide, according to official charts, was at 9.39pm. The supertanker needed high tide water to make it into port. But the port authority claims there was no rush. She had 16 metres of water under her.
To bring it back to the transit line, Sea Empress needed to change course and veer east. According to the Capt Cooney's crew reports, this was ordered. But it steamed past the desired line towards Middle Channel Rocks. It was off course.
At 8.08pm, according to Acomarit, as another course correction was tried, the first disaster happened. The ship's single hull hit the rocks. The Russian captain of the tanker, Eduard Bolgov, described the noise as "a terrible shuddering".
There would have a great deal of urgency on the bridge. Immediate action would have been required. Who gave the next order, and who carried it out, will be of crucial importance to the inquiry team.
Shortly after hitting the rocks, Sea Empress's engines were ordered to be either closed down or reduced to low power. At this point, as Acomarit believes the recorded tape of events now held by the Coastguard will show, the ship was about to lose steerage. By not going fast enough, changing rudder direction would have had little or no effect.
The tanker was now drifting towards St Ann's Head. A call from the bridge was radioed to the port authority. Minutes later the ship grounded at Mill Bay. It would be six days - in which time 70,000 tonnes of oil would be spilt - before it could be towed to safety.Reuse content