Fire aboard AS-31 Losharik: Brief Overview

Thoughts and a quick overview of what is known about the fire that took place aboard AS-31 Losharik. Also some clarifications since there are conflicting media narratives and facts surrounding this developing story.

BLUF: On July 1 the Russian special purpose submarine, AS-31 ‘Losharik’, designated as an atomic deep diving station (атомные глубоководные станции) suffered a catastrophic fire killing 14 crewmen, with 4 survivors (at first I heard 5 were rescued). The submarine itself seems to have been not far from its base and was towed back. The running version as I’ve heard it suggests that the fire occurred at fairly shallow depths, originating in the battery compartment of the submarine. The cause was a short circuit in the electrical system. Supposedly Losharik was conducting bathymetric surveys in the Barents (that’s the official story anyway). Most of the crew died from smoke inhalation attempting to save the submarine – the vessel was eventually towed back to base.

Electrical systems are not uncommon as a cause of fire aboard submarines, as are fires in battery compartments. Of course it is also possible that the Russian MoD has come up with a straightforward explanation for what caused the fire in order to give the media a plausible story to run with, while we do not know what actually happened given the nature and mission of this submarine. Hence the story of some sort of short circuit or electrical arcing leading to a fire makes sense, but at the same time should be taken with some skepticism.

At first glance the crew complement for that voyage appears unusually composed of senior officers. GUGI is a small, officer heavy service, with technical and engineering specialists. One the one hand it is not uncommon for everyone aboard such a vessel to be an officer given the technical expertise required, and it could be that such a large number of captains first rank are actually detailed to AS-31. However it is difficult to believe that the typical compliment, 20-25 crewmen, would consist of 7 Captains first rank, including two who had been awarded as heroes of the Russian Federation (Filin and Dolonski), unless they were conducting some important mission or perhaps test. Standard complement or not, either way, the deaths of these senior officers are likely to be a great loss not just for the Russian Navy, but also for GUGI’s technical efforts.

The official casualty list can be found here. It shows a loss of 7 captains first rank, 3 captains second rank, 1 Lt Col from the medical service, two captains third rank, and a captain-lieutenant. I think comparisons to Kursk are unhelpful, and out of place here, but it is a significant tragedy for the Russian submarine service.

AS-31 is an unarmed submarine designed for special missions, examination or installation of infrastructure along the ocean floor, research, measurement, and the like. The submarine has retractable arms to manipulate objects, but is not designed for advanced weapons testing (there is a different set of GUGI subs that perform this mission). The name Losharik is a nickname derived from the visual appearance of its specially designed pressure hull, composed of interlinked spherical compartments.

HI Sutton does good cutaways and 3D models, although I fear that this resource is overused as a single-source of visuals on Russian special purpose subs. There’s a strong chance that the interior might not quite match what people imagine it to be. Still the cutaways are quite useful to get a general sense of what it might look like.

Rough specs based on conflicting sources, none of which especially agree with each other:

• approximate length 74 meters
• 2100 tons displacement when submerged
• composed of 7 spherical compartments (some show as 6)
• crew 20-25
• diving depth 3000m + (perhaps up to 6000m)
• speed 6 knots submerged

I doubt the submarine’s voyage had anything to do with the timing of NATO’s ASW exercise in the Norwegian Sea, Dynamic Mongoose, though it is possible this submarine would be sent to pick up anything interesting left on the ocean floor – it is capable of such missions.

Losharik entered service in early 2000s, and became operational some years later ~ 2009. Although BS-136 is often cited as the carrier mother ship for Losharik, a modified Delta III, in reality BS-136 is not considered operational and most expect this submarine to be officially retired. There was news in 2013-2014 that Orenburg was going to be retired in the near future, and the submarine is far too old to merit life extension. Therefore the carrier is most likely BS-64 Podmoskovye which has been operational since 2017. I will edit this post later with links.

AS-31 belongs to GUGI, the Defense Ministry’s Main Directorate of Deep-Sea Research (10th Department). This is a specialized service that is not part of the regular Russian Navy, but answers directly to the Ministry of Defense as an intelligence and special missions organization. GUGI operates special purpose submarines, ocean going research ships (for example Yantar-class), and divers known as ‘hydronauts.’ Often media accounts conflate the work of GUGI, and its ships/submarines, with that of the regular Russian Navy, and it’s submarine force, which is not the case.

Losharik belongs to the 29th Submarine Division (previously listed as a separate brigade). This is a separate division in the Northern Fleet, based at Olenya Guba next to the town Polyarny. It is often erroneously reported as being at Severomorsk, or headquartered there, neither of which is true. The bay is near the main Northern Fleet submarine base of Gadzhiyevo on the Kola Peninsula. Other submarines of the 29th include the smaller special-purpose diesel-electric classes and larger modified motherships, based on reconfigured SSBN hulls.

Submarines belonging to GUGI include:

• 1-3 project 1910 Kashalot (UNIFORM) atomic deep-diving station
• 1-3 project variants of 1851/1 Nelma (X-RAY) and (PALTUS) carried atomic deep-diving stations
• BS-64 Podmoskovye (modified Delta IV SSBN), mother ship for AS-31
• BS-136 Orenburg (modified Delta III SSBN) non-operational, expected to be written off
• B-90 Sarov diesel-electric submarine, appears to be a systems development/testing platform
• K-329 Belgorod (modified Oscar II) recently launched from shipyard. Multipurpose platform able to carry smaller submarines, drones, nuclear powered torpedoes, etc.
• Project 09851 Khabarovsk, (modified SSBN) another multipurpose platform laid down in 2014 currently under construction

A brief slideshow of GUGI’s various children

Click to view slideshow.

Comments or suggested edits are welcome