Last December a 25-year-old tanker, the Erika, broke up and sank off the coast of Brittany, causing one of the worst oil spills Europe has ever seen. The Erika had cleared her safety inspections and was deemed seaworthy by the authorities: it was the accident the industry said could never happen. Tom Mangold investigates what went wrong, and asks why the tanker industry seems unable to steer itself away from the rocks.