An urgent safety warning has been issued after lorries toppled over during a ferry crossing in rough seas.
Nine lorries fell on to their sides and cars were crushed when European Causeway, operated by P&O Ferries, was sailing from Larne to Cairnryan on December 18 last year.
An inquiry by the Marine Accident Investigation Branch (MAIB) found at least six drivers had remained in their cabs despite being instructed to leave the ro-ro (roll-on/roll-off) deck after parking.
No-one was hurt during the incident, but one of the drivers was trapped in his vehicle and needed to be rescued by the emergency services in Scotland.
International regulations state that passengers are not allowed to remain on ro-ro decks as they are in danger of asphyxiation by fire or as a result of systems used to tackle fires.
The MAIB's investigation found that the problem of lorry drivers remaining in their vehicles on ferries is "not unique to this route or to P&O".
It issued an urgent safety warning which stated that ro-ro decks are a "hazardous and potentially life-threatening environment" and should only be occupied by professional seafarers.
Drivers who remain on the deck may delay an emergency response to a fire, which could result in "catastrophic consequences to the whole vessel, its passengers and the environment", the MAIB added.
It recommended that the Road Haulage Association should alert its members about the European Causeway incident and encourage them to take "robust action" over the issue.
