Preliminary assessment of new information on the sinking of the passenger ship M/V ESTONIA

Background

The passenger ship M/V ESTONIA sank on 28 September 1994 during a voyage from Tallinn to Stockholm. Of the 989 people on board, 852 died. In accordance with an agreement between the prime ministers of Estonia, Finland and Sweden, a joint accident investigation commission (JAIC) was formed to investigate the accident. A final report was published in December 1997.

On 28 September 2020, film material was published showing a hole in the starboard side of the hull. The starboard side of the vessel has previously not been possible to examine since it has been lying down towards the seabed.

The Estonian Safety Investigation Bureau initiated a preliminary assessment of the new information and requested assistance from the corresponding authorities in Finland and Sweden. The Safety Investigation Authority, Finland, and the Swedish Accident Investigation Authority decided to assist the Estonian authority in its assessment.

The purpose of a preliminary assessment after a marine accident is normally to consider whether an accident investigation should be initiated. In this case, the preliminary assessment aims to consider whether the new information gives reason to revise the conclusions drawn in the 1997 report, whether new investigative measures should be taken and, if so, which ones.

Focus of the work

It is clear that the vessel has moved on the seabed so that its starboard side, which previously lay down against the seabed, is now partially visible. The new surveys that are being conducted aim to examine the damage on the starboard side and its origin. In that context, it is decisive whether the damage occurred before the vessel sank or afterwards, e.g. when the vessel hit the seabed. In addition, the sea bottom conditions need to be examined more closely. As far as possible, the surveys also aim to get an overall picture of the underwater part of the hull in order to be able to assess to what extent it is damaged.

Initial investigation measures

During the autumn of 2020, the investigation authorities had the opportunity to review, in the presence of the film company, the unedited raw film material, which was published in some parts on D-play on 28 September 2020.

The investigation authorities have examined M/V ESTONIA's bow visor, which is stored in Sweden. The bow visor has been 3D-scanned. Calculations have been made i.a. to determine the length of time the bow visor may have floated to assess whether the visor, after detaching from the ship, may have damaged the vessel's hull.

The Swedish part of the investigation team has conducted interviews with Swedish survivors of the accident. Corresponding interviews with Estonian survivors are conducted by the Estonian authority. Survivors from other states have also been interviewed.

On 18 December 2020, the investigation authorities agreed that there was reason to carry out surveys on site. Among other things, it was judged that an examination and documentation should be done of the vessel's hull, existing damage in the hull and especially the damage in the starboard side that was not previously documented. The seabed around the ship should also be documented. Furthermore, it was assessed that there might be a need to take samples of both the material in the hull and the seabed for closer analyses.

Due to this, the Swedish Accident Investigation Authority requested the government to facilitate further investigation measures by amending the legislation that aims at protecting M/V ESTONIA. Such legislative amendments were implemented in both Sweden and Finland and entered into force on 1 July 2021.

Pre-survey on site

The safety investigation authorities of Estonia and Sweden carried out a pre-survey at the accident site on 8-16 July 2021. The primary purpose was to examine the condition of the sea bottom and the position of the vessel. In this context the Swedish Accident investigation Authority cooperated with i.a. the Geological Survey of Sweden, the Swedish Geotechnical Institute and Stockholm university. The Estonian authority cooperated i.a. with the Technical University of Tallinn (TalTech).

The work primarily included examination of the seabottom and the vessel with various forms of sonar instruments. Some photographic documentation with ROV (remotely operated underwater vehicle) was also done.

Among the measures that were taken the following can be mentioned:

• Multibeam sonar with equipment mounted on ships driving over the area.
• Sidescan sonar with equipment towed by a ship through the water.
• Scanning sonar (Mesotech) with equipment that is lowered and placed around the wreck.

The pre-survey was carried out by the Estonian multipurpose icebreaker EVA 316 and the Swedish research vessel ELECTRA af ASKÖ.

Several parts of the survey were conducted by Stockholm university.

Findings after the pre-survey

The data collected during the pre-survey was extensive. Immediately after the pre-survey the following findings were made:

• The two holes filmed by documentary filmmakers, were confirmed and documented with scanning sonar and ROV-camera. Adjacent to the holes there are a number of cracks in the hull and between the holes there is a longer indentation in the hull which is estimated to be just over 20 meters long.
• Part of the wreck is situated in very soft clay. There are also sections of the bottom near the wreck with boulders, hard bottom and bedrock. Whether those have affected the emergence of the two holes in the hull that have been examined, is however too early to say.
• When examining the vessel with scanning sonar, the results indicated that there is an opening in the vessel's bow. ROV examination with camera confirmed that the vessels's bow ramp was no longer in place but detached from its hinge brackets and now lies on its side, leaving an opening into the vessel's car deck.
• Other damage to the ship was also documented. There are i.a. deformations on the stern that may correspond to the stern hitting the bottom first.

Results of the pre-survey

The survey conducted with Mesotech sonar was performed by Abbott Underwater Acoustics, LLC. A report on the Mesothech work External link, opens in new window. has been handed over to the safety investigation authorities of Estonia and Sweden.

During the pre-survey, there were seven examinations made with ROV-video. The ROV-videos have been published on the Estonian Safety Investigation Bureau’s website External link..

The ROV filming carried out at M/V ESTONIA was carried out by an Estonian ROV operator who also described the dives in a report. The dive report Pdf, 994.2 kB. has been translated from Estonian.

Stockholm university's report on the conditions of the sea bottom External link. at the accident site was published in November 2021. The report states, among other things, that exposed bedrock has been identified next to where the major damage in M/V ESTONIA’s hull is found along the northern side of the wreck. The bedrock appears from ocular inspection of its texture and visible parallel jointing to be igneous, likely granite or syenite.

The surveys of 2022

During the early summer of 2022, a 3D laser scan of M/V ESTONIA was carried out. The Estonian investigation authority procured the laser scan and awarded the task to a consortium consisting of ESC Risk Management OÜ and Baltic Taucherei- und Bergungsbetrieb Rostock Gmbh as the main contractors. The laser scanning itself was carried out by Kraken Robotics.

In June 2022, a photogrammetric survey of M/V ESTONIA was carried out. This means that the ship was photographically documented. The Swedish Accident Investigation Authority procured the photogrammetry and awarded the contract to Ocean Discovery AB and JD-Contractor A/S. The photo documentation resulted in approximately 45,000 photographs. The photographs have been compiled into a 3D model by using photogrammetry.

So far, the work has not revealed any facts that contradict the technical explanation for the accident given in the 1997 report of the Joint Accident Investigation Commission (JAIC). The surveys are primarily focused on finding the causes of the damage noticed on the starboard side of the vessel (which became visible since the ship has turned around 13 degrees over the years). However, there is also reason to try to straighten out some of the question marks that have been raised over the years regarding the accident.

In that context, SHK has, among other things, asked questions about whether the Swedish Armed Forces has any information that can shed light on the course of events, as well as whether there is information about the transports of military equipment that took place on Estonia and previously have been subject to review. The Armed Forces has answered Pdf, 1.3 MB. SHK’s questions in writing.

Interim report 23 January 2023

The 23 January 2023, the investigation authorities published an interim report that describes the surveys that have been carried out so far and the preliminary conclusions that can be drawn from them. Furthermore, a large part of the photo documentation from the 2022 surveys has been made available to the public on the website estonia.shk.se External link..

The interim report Pdf, 42.4 MB. draws the following preliminary conclusions:

• The wreck of M/V ESTONIA is in poor condition, with severe structural damage.
• The location of the outcropping bedrock under the hull matches the location of the deformation on the hull.
• Based on the evidence gathered so far, there is no indication of a collision with a vessel or floating object.
• Based on the evidence collected so far, there is no indication of an explosion in the bow area.
• The Estonian and Swedish investigation authorities have analyzed the factual information contained in the 1997 JAIC report and assess that M/V ESTONIA was not seaworthy.

Surveys in the summer of 2023

In July 2023, further surveys of the M/V ESTONIA were carried out with the help of the Norwegian company Reach Subsea A/S. The surveys were carried out with two different underwater robots (ROVs).

With the help of a small ROV, the parts of the cargo hold (car deck) that could be accessed were filmed. The footage will be analyzed more closely and then made available to the public.

The bow ramp, which previously has detached from the vessel, was salvaged. It has been taken to Estonia where it will be subject to further investigation.

Some of the metal near the damage in the vessel's starboard side was sawed off and salvaged for further examination. A few more metal parts cut from the hull by divers in the 1990s were salvaged. An entire windowpane and parts of another window were salvaged. One of the bow ramp's two preventer cables was salvaged.

A drill sample was taken on the bedrock near the forward part of the damage on the starboard side of the vessel.

Samples have been taken of the growth that is found mainly on broken surfaces in the vessel’s plate. These samples will be analyzed in more detail by Stockholm university.

Results of the surveys

For the purposes of the preliminary assessment of M/V ESTONIA, several studies were commissioned in 2023. The reports of the studies have been published below.

Reports of the Estonian Forensic Science Institute

During the surveys carried out in the summer of 2023, a sample was taken in connection with the front damage on the starboard side of the hull. Some of the steel at the edge of the damage was sawed off and salvaged for closer examination. An Estonian laboratory (Estonian Forensic Science Institute) has examined the sample. The laboratory has presented its conclusions in three reports Pdf, 2.3 MB. and stated that:

There are no signs of contact or collision with any metal object.

There are no traces of explosive substances.

There are no characteristic signs indicating that the material has been exposed to an explosion. The same applies to the salvaged bow ramp and the photographic material showing car deck, the vessel’s bow and the damage on the starboard side.

Report on drill samples from bedrock

During the surveys carried out in 2023, a drill sample was taken from the rock formation located next to the front damage on the starboard side of the hull. The drill sample was submitted to Stockholm university, which sent part of the sample to Vancouver Petrographics in Canada, where a 0.03 mm thick disc was cut out for further analysis. Stockholm university has analyzed the sample Pdf, 1 MB. and assesses that it is very likely gneiss, which is a form of ancient rock.

Biogeochemical Report

During the surveys of M/V ESTONIA that were carried out in 2023, samples were taken, among other things, on the surface of the hull in connection with the damage found in the starboard side of the hull. The samples have been analyzed by Stockholm university Pdf, 58.2 MB.. Stockholm university states in its conclusions that the material and deposits found in connection with the front damage on the starboard side of the hull are the result of natural processes such as biological growth, accumulation of sediment and corrosion.

Report from examination of M/V ESTONIA's bow ramp

On behalf of the Swedish Accident Investigation Authority, a visual examination of the salvaged bow ramp has been carried out on site in Estonia by Element Materials Technology. The main purpose of the examination was to compare the bow ramp's appearance and damage with the sequence of events described in the technical report: "MV ESTONIA Bow arrangement collapses - Sequence of events", Gothenburg, November 2007, Jan-Ove Carlsson.

Nothing has been found during the examination that contradicts the description of the course of events described in the documents, except that the ramp's locking hooks are assessed to have been latched at the time of the accident. The separation of the railing most likely occurred as part of the accident. No evidence is noted suggesting that the bow ramp, or the railings, have been separated from the hull by machine tooling or thermal cutting. Report from Element Technology AB Pdf, 5.4 MB.