[4] The ship had taken part in the NATO exercise Trident Juncture, and the Norwegian Armed Forces initially stated that it was on its way back to its home port at the Haakonsvern Naval Base.

In contrast to Helge Ingstad, Sola TS only suffered minor damage to the bow after the collision and was never in danger of sinking.

Three minutes before the collision, Sola TS asked the Fedje Vessel Traffic Service Centre which ship was approaching.

The bulkhead lining on the starboard side of the bow was bent in several places, the anchor cleat was pushed in and had a hole in the upper part.

[21] According to the audio log that was later published by Verdens Gang, Helge Ingstad reported a loss of momentum and somewhat later that the ship had run against the ground.

[27] Frigates of the Fridtjof Nansen class are equipped with a one megawatt (1,300 hp) steerable electric azimuth thruster from Brunvoll AS.

[32] In the collision, the anchor cleat on Sola TS tore a long gash in 1⁄3 of the hull on the starboard side of the frigate.

[34] Later investigations have shown that when the ship was abandoned, the vast majority of watertight bulkheads and hatches were left in an open position.

[37][38] The lifting operation was led by the Royal Norwegian Navy with the support of Defense Material in collaboration with the external actors BOA Management and DNV.

[45] In a press conference later the same day, the navy rejected criticism of the salvage operation and claimed that the cables had been installed correctly.

[46] The two crane ships Gulliver and Rambiz from the Belgian company Scaldis were hired to lift the frigate onto the semi-submersible barge BOAbarge 33.

[55] The Accident Investigation Board for Transport questioned everyone who was present on the bridge of both ships, as well as on the tugboat Tenax which escorted the tanker.

The personnel on the bridge of Helge Ingstad both before and after the change of watch 20 minutes before the accident were of the opinion that the lights they saw from Sola TS were from a stationary object in connection with the Sture Terminal, and not from an oncoming ship.

Contrary to the International Regulations for Preventing Collisions at Sea,[60] "Sola TS" had the same deck lights on after the ship left as when they were still at the terminal.

[1][3] The Norwegian Safety Investigation Authority also pointed out that the forward-facing deck lighting on Sola TS made it difficult for the frigate's bridge crew to see the navigation lanterns and the signaling from the Aldis lamp on the tanker.

One recommendation is addressed to the Ministry of Defence, two to the shipping company Tsakos Columbia Shipmanagement S.A., which owns Sola TS, two to the Coastal Administration and one to the Norwegian Maritime Directorate.

Based on the knowledge the crew had in the current situation and under the given conditions, it is nevertheless understandable that it was decided to evacuate the vessel and not risk life and health.

[74][75] The Norwegian Armed Forces concluded after its internal investigation that it was not one single error that caused the collision, but a long series of events.

[citation needed] In September 2019, the Ministry of Defence entered into a contract with PriceWaterHouseCoopers to carry out an external and independent review of the salvage operation, in the period from when the crew was evacuated until the vessel was brought to Haakonsvern Naval Base.

[78] In the report from the investigation on 16 December 2019, PriceWaterHouseCoopers concluded, among other things, that there was technical room for maneuver to save the frigate, that the actors overestimated how secure the frigate was and underestimated the load the anchors on land were exposed to, and that the Royal Norwegian Navy and FMA underestimated the complexity of the salvage operation.

[79] The State at the Ministry of Defence sued the owner of the tanker TS "Sola", Twitt Navigation Limited, who counter-sued.

The Ministry of Defense states that DNV GL should have discovered that the hollow propeller shafts could cause water to spread quickly.

[83] However, when the final accident report came in, it became clear that DNV GL was not to blame for the catastrophic consequence of the frigate's collision with the tanker.

[84] In 2019, the Norwegian Armed Forces announced legal action against the Spanish shipbuilder Navantia, which built Helge Ingstad.

In August 2024, the Government Attorney confirmed to the Norwegian newspaper Verdens Gang that there was a legal process between the Ministry of Defense and Navantia.

[18] During the police investigation, the prosecution gave suspect status to the watch commander on Helge Ingstad, the captain and the pilot on the tanker and the person who was on duty at the traffic center on Fedje.

[88][89] In May 2022, the prosecuting authority brought charges against the officer who was the responsible duty manager at Helge Ingstad when the accident occurred.

[90][91] The prosecuting authority also notified the Ministry of Defense that there was considered to be reason to impose corporate punishment on the Armed Forces, with a deadline of 20 May 2022 to comment on the notification.

In his prosecution decision, the Attorney General concluded that the entire bridge crew on Helge Ingstad acted negligently.

[98] The District Court found that the duty officer's actions prior to the collision with the oil tanker were "clearly unjustifiable".