New video has shown the moment a cargo ship ploughed into a fuel tanker hired by the US military off England in the North Sea.
The collision between the Solong cargo ship and the 183-metre-long Stena Immaculate oil tanker left the Solong on fire and sent jet fuel spilling into the sea.
One crew member is missing and presumed dead.
Video from another ship's thermal imaging camera shows the Solong hitting the Stena Immaculate, causing an immediate explosion.
Small pockets of fire were still burning on the top deck of the Solong and the blaze on the Stena Immaculate was extinguished by Wednesday.
Both ships were "stable" at sea, according to the coastguard.
The Solong's 59-year-old Russian captain remains in the custody of British police after being arrested on suspicion of gross negligence and manslaughter.
Police have been granted a further 36 hours to question the captain.
Experts have told the ABC there is no evidence the cargo ship tried to take evasive action before Monday's collision, which has sparked fears of an environmental disaster.
"We can see that something was potentially amiss on the Solong, as no avoidance or slow down can be seen from the route tracking," said Andy Teasdale, a marine safety advisor to the London-based the Institute of Marine Science, Engineering and Technology.
Gholam Reza Emad, from the University of Tasmania's Australian Maritime College, said there was a good chance that the captain and the chief master of the Solong were tired and fatigued.
"Looking at the historical AIS data [a maritime communications device] … for me it shows the crew were constantly working," Dr Emad said.
"The data of the day of the accident shows that the course and speed did not change for hours, which shows no suspicious action.
"It seems the officer in charge at 09:47 [the time of the collision] did not see the ship (in the foggy condition) or were distracted and not paying attention at all."
Multiple factors generally behind marine collisions
Benjamin Brooks, an associate professor of seafaring and maritime operations at the University of Tasmania, told the ABC that maritime accidents such as this one always came about because of "complex and multi-dimensional" factors.
"There is generally never one factor," he said.
"Over 80 per cent of accidents involve human factors, but it is important to recognise that this doesn’t mean we should immediately blame the people."
Dr Brooks said it was likely that crew members had lost situational awareness in any circumstance where two ships collide with each other.
"'Situational awareness' is the term that is used within human factors circles to describe the level of awareness that operators have of the situation that they are engaged in," he explained.
"It focuses on how operators develop and maintain a sufficient understanding of 'what is going on' in order to achieve success in task performance."
Dr Brooks said engine or rudder failures could also be a contributing factor in marine collisions.
What are investigators looking at?
Andy Teasdale said investigators would now be looking at both ships' data recorders — like an aeroplane's black box — as well as listening back to radio messages between marine traffic controllers and local coastguards.
"All those rescued from the vessels will be interviewed and given precautionary drug and alcohol tests,” he said.
The University of Tasmania's Dr Emad said the vessel's condition and maintenance record as well as environmental and weather conditions at the time would also be looked at.
Where are Solong and Stena Immaculate now?
The coastguard said the Solong had been towed to a safe place, while the Stena Immaculate remained at anchor.
This week, Reuters reported that a fire was still burning on the Solong but that it was under control.
The Stena Immaculate is one of 10 tankers that transport fuel to the US military as part of the Pentagon’s US Tanker Security Program.
Having the Stena Immaculate out of action is likely to cause logistics challenges for the US military, shipping industry sources told Reuters.
What happens next?
"It may be several days before the hulls have cooled sufficiently to allow boarding, assess the damage, and get towlines in place to move the damaged hulls." Mr Teasdale said.
"Then salvage crews will secure the bunkers remaining on board and get them to a safe port, which reduces further damage, stops potential pollution spreading and helps investigators to establish the root causes of the incident."
British police said the Solong's captain remained in custody while British detectives continued their investigation led by the Marine Accident Investigation Branch.
ABC/wires
