There is an "industry-wide" issue of lorry drivers putting their lives at risk by remaining in their cabs while at sea, an investigation has found.
It comes after nine HGVs toppled over and 22 vehicles were damaged on the P&O European Causeway service between Larne and Cairnryan in December 2018.
After the incident it emerged that six drivers had stayed in their cabs.
The December 2018 incident was brought on by high winds, which resulted in one lorry driver, whose vehicle had been overturned, being freed by emergency services at the Dumfries and Galloway port.
The MAIB report into the incident said the practice of drivers staying in their cabs while at sea was not uncommon in the industry.
Andrew Moll, chief inspector of marine accidents, said it had found that weather conditions had "not been sufficiently considered" when setting the course of the ship, nor when applying lashings to freight vehicles loaded aboard.
"The investigation further highlighted the problem of freight drivers remaining in their cabs on the vehicle deck when the ferry is at sea," he said.
"Drivers remaining in their vehicles not only put themselves at risk, but they also place at risk other passengers and anyone who may have to rescue them.
"Perhaps, most importantly, crucial emergency responses, such as to a fire, can be delayed until all passengers are accounted for."
He said he had written to ferry firms around the UK to highlight the dangers of drivers staying on vehicle decks and encouraged them to "eliminate this dangerous practice".
P&O has also been advised to enhance its safety management system in light of the incident.
Martin Reid, the Road Haulage Association's director for Scotland and Northern Ireland, said: "Drivers must comply with these regulations which are there to keep them and others safe in the event of an emergency.
"Our message is don't put people at risk by ignoring them."
A statement from P&O said it accepted the recommendations of the MAIB "in full".
It added that the company had already updated its Safety Management System (SMS) to include best practice guidance from the Maritime and Coastguard Agency.
Source: BBC News