Underwater operation at a depth of 554 metres: how Turkish rescuers are searching for those missing from Filo Jet

Several days after the high-speed passenger vessel Filo Jet sank off the coast of Kyrenia, the search-and-rescue operation has entered a fundamentally new phase. The main work is now being carried out not only from the surface of the sea: Turkish Navy specialists are examining the vessel’s hull, resting at a depth of 554 metres, with the help of remotely operated underwater vehicles.

The video shows an operator controlling an ROV — a remotely operated unmanned underwater vehicle — from the command centre of the TCG Alemdar rescue vessel. This robotic technology is now allowing specialists to work with the sunken vessel at a depth inaccessible to conventional divers.

Why a depth of 554 metres fundamentally changes the nature of the operation

The Filo Jet crash site is far deeper than the usual capabilities of professional divers. At such a depth, human factors, pressure and the need for prolonged decompression make the direct presence of divers extremely difficult and dangerous.

Robotic systems are therefore carrying the main burden. According to Anadolu, the ROV is capable of operating at depths of up to 1,000 metres and is equipped with cameras and a manipulator that can grasp objects and lift them to the surface. The maximum load the vehicle can lift is approximately 135 kg.

This means that the robot is being used not merely as a camera. Its task is effectively to become the rescuers’ “hand” at depth: examining the hull, entering accessible parts of the sunken vessel, locating people and objects, and helping bring them to the surface.

Several specialised systems are involved in the operation

The key vessels in the operation are the TCG Alemdar and TCG Işın. According to Anadolu, the area is being surveyed by 9 vessels and 11 aircraft. Work is being carried out around the clock.

TCG Işın is performing one of the most important tasks — surveying the seabed and determining the position of objects. The vessel is equipped with a side-scan sonar capable of detecting objects at depths of up to 1,000 metres, while a multibeam echosounder allows the seabed terrain to be scanned in detail at depths of up to 3,000 metres.

For operations of this kind, it is crucial not only to locate the hull but also to determine its exact position and condition. At a depth of more than half a kilometre, visibility may be limited, and any work on the hull must be carried out with maximum precision to avoid damaging it or losing potentially important evidence.

A separate task — searching for the “black box”

At the same time, specialists are trying to locate and recover Filo Jet’s voyage data recorder. This could be of enormous importance to the investigation into the causes of the disaster.

If the device has survived and the information on it can be read, investigators will be able to obtain data on the vessel’s operation immediately before the accident. Combined with survivors’ accounts, the condition of the hull and the results of the underwater survey, this could help reconstruct the sequence of events in the final minutes before the sinking.

However, it is important to stress that the discovery of the hull at depth does not in itself mean that the cause of the disaster has been established. At present, official materials indicate that the investigation is continuing.

What is known about Filo Jet’s final minutes

Filo Jet was operating a route between Kyrenia and Taşucu in Turkey’s Mersin province. The vessel left Kyrenia around midday on 30 August. Shortly after leaving the port, it began taking on water through the bow and attempted to return, but sank.

The circumstances surrounding the initial ingress of water remain one of the investigation’s main questions. Reuters previously reported that survivors described unusual movements by the vessel and a strong impact before it began taking on water rapidly. At the time of the initial reports, however, the official cause of the accident had not been established.

Thus, the underwater operation is significant not only for the search for people. It could potentially enable investigators to establish exactly where the damage occurred, how quickly the flooding spread and what condition the hull was in after the accident.

Why the ROV footage matters to the investigation

The video published by Anadolu is of particular interest because, for the first time, it shows not simply rescue vessels on the surface but the technological side of the deep-water operation itself.

For maritime investigations, such material is highly significant: visual documentation of the hull’s position, the damage and the surrounding section of seabed can later be compared with sonar data, statements from the crew and passengers, and the results of technical examinations.

What happens next

At this stage, rescuers face two tasks at once: finding the missing people and conducting as complete a survey of the sunken vessel as possible. As of 4 September, 12 deaths and 16 people missing were reported; the search operation was continuing.

Work at a depth of 554 metres is not an ordinary diving search. It is a complex engineering operation involving sonar, multibeam scanning, dynamic positioning of vessels and robotic underwater vehicles.

That is why the footage published from aboard the TCG Alemdar matters not only as a documentary record of the tragedy. It shows how difficult the search for people and evidence becomes when the site of a disaster lies more than half a kilometre beneath the sea’s surface.

There is still no definitive explanation for the loss of Filo Jet. The main answers are likely to emerge after the underwater examination of the hull is completed, the objects found are analysed and, if the recorder can be recovered and read, its data are studied.