A preliminary report issued by Accident Investigation Board Norway (AIBN) into last month’s collision between the Norwegian frigate KNM Helge Ingstad and the Tsakos-owned Aframax tanker Sola TS in Hjeltefjorden, outside the Sture terminal highlights a series of failures by the frigate crew and misinterpretation of events.
The tanker suffered no major damage in the collision, but the frigate was holed and later sunk in shallow waters after its watertight integrity was compromised. One of the main causes of the incident was that the frigate crew initially assumed that the tanker was a stationery object and part of the oil terminal.
According to the report of the incident which occurred at night, the frigate crew first observed the lights of the terminal but did not realise that the tanker – which was then stationary with all deck lights on as it was due to depart – was a vessel and not part of the terminal.
The frigate was travelling at a speed of about 17–18 knots with its AIS set to receiver mode (receipt only, no transmission of own data), the vessel's navigation lights were lit and the vessel could be observed by radar. The frigate established a listening watch on the VTS's working frequency for the area.
After the tanker departed the jetty, the pilot observed the echo of a southbound vessel on the radar, which would cross his course line, but did not have an AIS signal for the vessel. The pilot called Fedje VTS and asked for the name of the vessel that was heading towards the tanker on the port bow. The VTS answered that they had no information about this vessel. The pilot and captain on Sola TS then tried to contact the vessel in other ways. They flashed the Aldis lamp, and the pilot requested a 10-degree course change to 000° from the captain on Sola TS.
Fedje VTS then informed the tanker that the vessel was possibly KNM Helge Ingstad, the pilot called the frigate and requested it to turn to starboard immediately. The frigate’s bridge crew replied that they could not turn to starboard before they had passed the object they saw on their starboard side.
Just after 04:00, the frigate was approximately 400 m from Sola TS. As the naval vessel did not change course, both the pilot and Fedje VTS called it requesting the vessel to act. Shortly thereafter, KNM Helge Ingstad carried out an avoidance manoeuvre, but it was too late, and the two vessels collided. The frigate lost control of the rudder and propulsion, drifting uncontrollably towards the shore, where it grounded. As the vessel started taking on water, its crew was evacuated.
The AIBN's preliminary assessment is that the accident was not caused by any single act or event,but can be explained by a series of interacting complex factors and circumstances. The investigation team is seeking to identify and understand these factors. So far, the AIBN has not seen any indication of technical systems not working as intended up until the time of the collision.
The AIBN has started to map how the accident developed after the collision and up until the time when all crew had been evacuated. In that connection, the Norwegian Armed Forces, Norwegian Defence Material Agency, the Norwegian Navy, the Norwegian Armed Forces Material Safety Authority (NAFMSA) and the ship designer Navantia have been informed that they will be notified of a critical safety issue. The notification concerns the frigate’s watertight integrity.
Based on its preliminary description of the sequence of event, the AIBN has identified a need for further and more thorough investigations in the following areas: human factors, collaboration on the bridge, training and procedures, traffic control, language and communication, technology, and technical, operational, organisational and strategic choices.