The Grand Neptune cargo vessel had to make a 360-degree turn off Dover
A cargo vessel had to make a 360-degree turn in the Dover Strait off Kent to avoid a cruise liner that was crossing the shipping lane, a report has said.
The Grand Neptune's emergency turn in May was to avoid the Costa Atlantica, the Marine Accident Investigation Branch (MAIB) report revealed.
The report said the Costa Atlantica had used inaccurate information to perform a "potentially confusing" manoeuvre.
But it added the cruise liner owner had since taken steps to improve safety.
It also said the owner of the Italian-registered cruise liner had conducted an investigation after the incident, which happened with 1,700 passengers on board.
The Costa Atlantica was travelling at a speed of 16 knots from Le Havre in France to the Essex port of Harwich.
The report said the Grand Neptune, a Panamanian-registered car-carrying vessel, had to manoeuvre hard to starboard to avoid the 85,000-tonne liner.
It said the bridge team on Costa Atlantica were "slow to appreciate the risk of collision with the Grand Neptune" and did not appreciate the possible inaccuracy of the information.
The MAIB also said the information on which the Costa Atlantica's master based his decision to cross the shipping lane was inaccurate.
It added that this information was derived from the results of a radar trial manoeuvre "with which neither the master nor the officer of the watch were familiar".
The report said: "The manoeuvring of Costa Atlantica during the vessel's crossing of the south-west traffic lane was potentially confusing, and the intentions of her master were not readily apparent to other vessels."