Volkswacht Bodensee - Initial expert report blames tanker for collision off Istanbul

The ALSU collided early on Wednesday with the Tugberk Imamoglu, a cargo vessel carrying rolled steel, 18 nautical miles off Silivri on the western edge of Istanbul province.

Officials said the damaged cargo ship sank "very quickly" in waters about 900 metres (3,000 feet) deep, leaving all 10 crew members missing.

The ALSU, which was empty at the time, was not damaged in the collision, the cause of which was not immediately clear.

But an expert report prepared for the Silivri prosecutor's office, a copy of which was seen by AFP, indicated there had been multiple breaches of safety procedures aboard the tanker.

"The fundamental root cause... resulting in a catastrophe, was the deficiencies and failures on the bridge of the M/T ALSU," it said.

It said an inexperienced third officer was at the helm and there was no lookout on duty, describing it as "serious negligence".

"No helmsman or lookout was posted on the bridge and the second officer, who had only recently joined the vessel and lacked experience, was left alone on watch," the report said.

The captain was sleeping in his cabin at the time of the collision and not at the bridge, in what the report described as a clear violation of the so-called "Watch Condition B" safety procedures.

It also said no early action was taken to reduce speed and avoid a collision, such as stopping the engine or putting the ship into reverse.

- 'Ghost vessel' -

The Tugberk Imamoglu, which was carrying 4,200 tonnes of rolled steel and reinforcing bars, is a 90-metre Turkish-flagged cargo ship built in 1990, according to the VesselFinder tracking website.

The report also identified shortcomings aboard the cargo ship.

It said the vessel's automatic identification system (AIS) was not functioning -- suggesting it had been switched off, was malfunctioning or had been tampered with.

"As a result, the ship navigated like a 'ghost vessel', effectively invisible to other traffic," the report said.

Although the vessels had agreed by radio to pass port-to-port, the Tugberk Imamoglu suddenly altered course to starboard when the ships were within 0.5 nautical miles of each other, veering across the tanker's bow, the report found.

Search and rescue operations continued on Thursday, involving 18 vessels, five helicopters, two drones and an aircraft, as well as a navy vessel conducting underwater searches.

Anadolu state news agency said nine ALSU crew members, excluding the cook, had been detained and questioned by police.

Six of them were appearing in court on Thursday.

A.Ammann--VB