The 3rd series of the Channel Five TV documentary Warship – Life at Sea, following HMS Northumberland on patrol inside the Arctic Circle, has revealed a Russian SSN collided with her towed array sonar. Here we take an overview of events and their context.
After briefly participating in the Joint Warrior/GROUPEX with the Carrier Strike Group (October 2020) off the east coast of Scotland, Northumberland was tasked to head north. Intelligence had been received that Russian submarine were heading out into the Atlantic from their bases around Murmansk. This is interesting in itself as it indicates that NATO is still more than capable of detecting Russian submarine movements early in their outbound voyages, most likely through a combination of SSNs operating in the Barents Sea, underwater acoustic sensor arrays, maritime patrol aircraft and satellite imagery.
The footage shows that Northumberland has been in contact with the Russian boat for some time. Clearly, the Type 2087 Towed Array Sonar (TAS) remains highly effective and able to detect submarines at long ranges. The passive element of the TAS is a thick rubber-coated tow cable, attached to a string of hydrophone elements that can be streamed from a reel on the quarter-deck through a small hole in the stern. The array can be up to about a mile in length, keeping it well away from any noise generated by the ship. It also allows the sensor to get well below thermal layers in the water column that may limit the noise that a hull-mounted sonar can detect. When streaming the TAS, the frigate is constrained in how she can manoeuvre.
Entering service in 2004, the 2087 (CAPTAS-4) is made by Thales and has gained a formidable reputation. It underwent a major technical refresh in 2017 and is still subject to ongoing incremental processing and AI software upgrades under the ASW Spearhead programme. It is planned that as the Type 23s are decommissioned, the 2087 equipment will eventually be migrated to the Type 26 replacements.
Northumberland appears to have been only using passive sonar (ie relying on noise emitted by the submarine). This may indicate that it was an older boat as the latest Russian submarines are much quieter and hard to detect using passive methods only. The CO decided to close the range to a few thousand yards to ensure that the submarine becomes aware that she has been detected by the frigate. The Type 23s are designed to be quiet and hard for submarines to detect when running on electric motors, power is provided by diesel generators sited well above the waterline. Deliberately letting the submarine know it has been detected is a way of signalling the hunter’s superiority and indicating that in a shooting war they would likely have been sunk some time ago. (Likely by a Sting Ray torpedo delivered by the embarked Merlin helicopter.)
To the obvious surprise of everyone in the ops room (followed by some nautical language), the submarine then manages to collide with the towed array. It is unclear whether this was a deliberate act in response to the embarrassment of detection or just an accident. There would be a modest risk to the submarine of wrapping the cable around its propellors or catching on hydroplanes. Although unlikely to stop the boat or impair its control, a snagged cable could create unwanted noise. Contrary to the suggestion of many media headlines, the ship itself was not hit but the impact with the TAS was loud and clear in the Ops room and it is likely there was damage to the TA, even if it was not severed.
The Royal Navy is no stranger to the Barents Sea and the freezing and stormy waters in the Arctic Circle. The bravery and endurance of the naval and merchant sailors serving on the notorious Arctic convoys of World War Two is one of the outstanding feats of naval history. In the Cold War that followed, the RN and USN began to send conventional and then nuclear submarines to gather intelligence on the expanding Soviet Navy close to their home waters. The majority of RN submariners serving at the height of the Cold War were involved in demanding patrols in the Barents Sea, what they called, “going up around the corner”. Hunting and tailing Soviet submarines to record the sound signatures and gather intelligence on operating procedures was the primary goal. These tense patrols yielded enormous intelligence and gave NATO a major advantage in countering the huge Soviet submarine fleet but often entailed considerable risk. ASW frigates have always been deployed in the North Atlantic, North Sea and GIUK gap, although more rarely in the Barents Sea.
At least two Royal Navy submarines are known to have sustained serious damage after underwater collisions with Russian boats they were trailing. There were probably other incidents involving US, RN and Soviet boats that are not in the public domain or were officially attributed to “collisions with icebergs”. (There may have been collisions between RN warships and submarines but if so, they have not been publicly documented). In 1982, just after her service in the Falklands, SSN HMS Conqueror participated in ‘Operation Barmaid’. She was fitted with a pair of remote-controlled heavy steel cutting blades and television cameras specifically for the purpose of cutting and stealing a Russian TAS. She succeeded in her mission, taking the array from a Polish-flagged vessel and bringing the ‘trophy’ back to Faslane for analysis by US experts.Barents-Sea-Map
The development of towed array sonars in the 1980s allowed the frigates to become a more effective contributor to tracking the underwater threat. The number of Russian submarines is far smaller but today the RN has just 8 frigates with a TAS ‘tail’ and allocates at least one to be active or at very high readiness as Fleet Ready Escort (FRE), sometimes overlapping with Towed Array Patrol Ship (TAPS) duty in northern waters.
The RN rarely comments on these ongoing ASW operations or only provides very vague summaries. Allowing this documentary crew onboard Northumberland was a great decision and is helping to shine a light on the shadow war with the Russian navy that the RN (and NATO allies) have been continuously engaged with at varying levels of intensity since the 1950s.
In a typically bland statement confirming events, the MoD said: “In late 2020 a Russian submarine being tracked by HMS Northumberland came into contact with her towed array sonar. The Royal Navy regularly tracks foreign ships and submarines in order to ensure the defence of the United Kingdom.” The work is arguably one of the RNs most important tasks but TAPS deployments in northern waters are not much fun for ship’s companies which have to endure long and sometimes boring periods, often in foul weather and freezing conditions. There are also limited options for a run ashore – short visits to Scottish ports, occasionally Norway (£8 a pint!) or Iceland. There can however be great professional satisfaction to be gained from being right at the ‘sharp end’, conducting operations with a challenging adversary and contributing in a very tangible way to UK security.
The TV Documentary was filmed in Autumn 2020 and follows two previous series recorded on HMS Trenchant and HMS Duncan. It is very watchable but obviously edited for maximum dramatic effect with music and excitable narration at times which sailors who do the job for a living may find slightly irritating. This style of documentary may not be to the taste of the purist but is generally effective at keeping viewers engaged. This first episode of this series showed HMS Northumberland monitoring the Russian AGI Viktor Leonov attempting to gather electronic intelligence from the Carrier Strike group. The next episodes promise to show more encounters with Russian ships and aircraft. There was also another twist in the story – the entire ship’s company subsequently contracted COVID and were forced to abandon the patrol early, returning to Devonport on 23rd December, spending Christmas in isolation.