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From BBC News


Page last updated at 12:55 GMT, Monday, 16 February 2009


Nuclear subs collide in Atlantic


A Royal Navy nuclear submarine was involved in a collision with a French nuclear sub in the middle of the Atlantic, the MoD has confirmed.


HMS Vanguard and Le Triomphant were badly damaged in the crash in heavy seas earlier this month.


First Sea Lord Admiral Sir Jonathon Band said the submarines came into contact at low speed and no injuries were reported.


Both the UK and France insisted nuclear security had not been breached.


Despite being equipped with sonar, it seems neither vessel spotted the other, the BBC's Caroline Wyatt said.


Our defence correspondent said HMS Vanguard, with "very visible dents and scrapes", had to be towed back into its home base at Faslane on the Firth of Clyde.


She said it might be that the anti-sonar devices, which hide the submarines, were to blame.


"This is clearly a one-in-a-million chance when you think about how big the Atlantic is," she said. "It is actually unbelievable that something happened."


The incident is being investigated on both sides of the Channel.


The two submarines are key parts of each nation's nuclear deterrent, and would have been carrying missiles, though both the UK and France have insisted there was no danger of a nuclear incident.



Launched in 1992

One of four British submarines carrying Trident nuclear missiles

Weighs 16,000 tonnes, 150m (492ft) long

Can carry 48 nuclear warheads on a maximum of 16 missiles

A two-year refit was completed in 2007 as part of a £5bn contract

Due to be replaced in 2024


The two submarines were carrying around 240 sailors between them. A French naval spokesman said the collision did not result in any injuries to the crew.


Le Triomphant is based at L'Ile Longue near Brest, north-west France. HMS Vanguard arrived back in Faslane on Saturday.


France's defence ministry said in a statement, dated 6 February, that Le Triomphant "collided with an immersed object (probably a container)" when coming back from patrolling.


"The sonar dome, at the front, was damaged. This incident did not cause any injuries among the crew and did not threaten the nuclear security at any time," it said.


"The submarine came back by its own means to L'Ile Longue, escorted by a frigate, as it is the usual practice when leaving or coming back."


'Large ocean'


Politicians have demanded more information on the incident.


Lib Dem defence spokesman Nick Harvey has called for an immediate internal inquiry with some of the conclusions made public.


"While the British nuclear fleet has a good safety record, if there were ever to be a bang it would be a mighty big one," he said.



Launched in 1994

One of four French ballistic missile nuclear-powered submarines (SSBN)

Displacement (submerged) 14,000 tonnes, 138m (452ft) long

Can carry 16 ballistic missiles with nuclear warheads

110 crew, including 15 officers

Submerged speed over 25 knots


"Now that this incident is public knowledge, the people of Britain, France and the rest of the world need to be reassured this can never happen again and that lessons are being learned."


Meanwhile, SNP Westminster leader Angus Robertson has called for a government statement.


"The Ministry of Defence needs to explain how it is possible for a submarine carrying weapons of mass destruction to collide with another submarine carrying weapons of mass destruction in the middle of the world's second-largest ocean," he said.


The Campaign for Nuclear Disarmament described the collision as "a nuclear nightmare of the highest order".


CND chair Kate Hudson said: "The collision of two submarines, both with nuclear reactors and nuclear weapons onboard, could have released vast amounts of radiation and scattered scores of nuclear warheads across the seabed."

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Seems it was The Sun that broke the story.


There is a lot of head scratching going on right now as to how this could have happened. The fact that both submarines survived without serious injury suggests a rather low speed collision. The sonar dome of Le Triomphant was apparently damaged, which suggests that the Vanguard was ahead of her. This in turn (combined with the low speed) begs the question: why didn't the French sub detect the British sub? Also, the Vanguard was apparently towed into Faslane, suggesting that perhaps sustained some propulsion damage? All speculation, of course.

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Further relevant info ...


From Daily Mail


British and French submarines packed with nuclear missiles collide beneath the Atlantic


By Ryan Kisiel, Tamara Cohen and Peter Allen

Last updated at 4:51 PM on 16th February 2009


British and French submarines armed with ballistic missiles threatened a nuclear disaster after colliding in the Atlantic.


The crash - which sparked disbelief among naval experts - is believed to have occurred after state-of-the-art technology fitted in both vessels, which is designed to detect other submarines, apparently failed completely.


Each boat is a key part of their respective countries' nuclear deterrent, ready to unleash hugely destructive weapons at a moment’s notice.


While both countries claim that security was not threatened by the collision, wide-scale enquiries are currently underway on both sides of the Channel.


French Navy sources confirmed that Le Triomphant, one of four strategic nuclear submarines of the ‘Force de Frappe’ (Strike Force), was returning from a 70-day tour of duty when it collided with HMS Vanguard.


Britain's most senior sailor, First Sea Lord, Adm. Jonathon Band, said the underwater crash posed no risk to the safety of the submarines' nuclear reactors and nuclear missiles.


But he offered no explanation of how the rare incident might have occurred.


'The two submarines came into contact at very low speed,' Band said in a statement. 'Both submarines remained safe.'


France's defence ministry said the ballistic missile submarines had been carrying out routine patrols when they collided.


'They briefly came into contact at a very low speed while submerged. There were no injuries. Neither their nuclear deterrence missions nor their safety were affected,' France's defence ministry stated today.


During heavy seas in the middle of the night between February 3 and 4, French sailors heard a loud ‘bang’ that all but destroyed the submarine's sonar dome.


This part of the boat should have detected the Vanguard in the first place, but Le Triomphant’s crew of 101 neither saw or heard anything before the collision.


Between them the submarines had 250 sailors on board.


A senior Navy source told The Sun: 'The potential consequences are unthinkable. It's very unlikely there would have been a nuclear explosion. But a radioactive leak was a possibility. Worse, we could have lost the crew and warheads. That would have been a national disaster.'


As inquiries began, naval sources said it was a million to one unlucky chance both subs were in the same patch of sea.


A Ministry of Defence spokesman said: 'It is our policy not to comment on submarine operational matters, but we can confirm that the UK’s deterrent capability has remained unaffected at all times and there has been no compromise to nuclear safety.'


The French last night also tried to play down the collision, with a Navy spokesman saying: ‘The collision did not result in injuries among the crew and did not jeopardise nuclear security at any moment.’


Le Triomphant took at least three days to limp back to her home port, although she did not have to be towed.


HMS Vanguard, by contrast, apparently had to be towed back to her home base in Faslane, Scotland with visible scrapes.


With a complement of 135, she is the lead boat of the Vanguard class of submarines which carry Trident ballistic missiles around the world.


Le Triomphant is also the lead ship in her own class of French nuclear submarines.


Both vessels boast 16 M45 ballistic missiles, weighing 35 tons each, which carry six warheads with a range of around 5000 miles.


Neither France nor Britain would confirm the exact date of the collision, but said it took place earlier this month. France issued a brief statement February 6 saying the Le Triomphant had struck 'a submerged object' that was probably a shipping container.


Naval experts were amazed by the collision.


'This really shouldn't have happened at all,' said Stephen Saunders, a retired British Royal Navy commodore and the editor of Jane's Fighting Ships. 'It's a very serious incident, and I find it quite extraordinary.'


He said while Nato countries let each other know what general area of the Atlantic they are operating in, neither submarine would have had a precise position for the other.


Saunders said submarines don't always turn on their radar systems or make their presence obvious to other shipping.


'The whole point is to go and hide in a big chunk of ocean and not be found. They tend to go around very slowly and not make much noise,' he said.


Lawmakers and disarmament advocates demanded an explanation of how the submarines could have failed to detect each other.


Britain's government 'needs to explain how it is possible for a submarine carrying weapons of mass destruction to collide with another submarine carrying weapons of mass destruction in the middle of the world's second-largest ocean,' lawmaker Angus Robertson of the opposition Scottish National Party said.


Stephane Lhomme, a spokesman for the French anti-nuclear group Sortir du Nucleaire, said its activists were on alert for any signs of radioactive leaks near French shores.


'This reminds us that we could have a new catastrophe with a nuclear submarine at any moment. It is a risk that exists during missions but also in port,' he said. 'These are mobile nuclear reactors.'


Britain's Campaign for Nuclear Disarmament called on Gordon Brown to end his country's nuclear submarine patrols of the Atlantic.


'This is a nuclear nightmare of the highest order,' said Kate Hudson, the group's chair. 'The collision of two submarines, both with nuclear reactors and nuclear weapons onboard, could have released vast amounts of radiation and scattered scores of nuclear warheads across the seabed.'


France’s Atlantic coast is notorious for being a ‘submarine graveyard’ because of the number of underwater craft, mainly German U-Boats, sunk in the area during the Second World War. The story of one was immortalised in the classic 1981 film Das Boot.


Two sailors died from a blast on a British nuclear submarine in March 2007. An oxygen generator blew up as HMS Tireless cruised beneath the Arctic ice. The tiny compartment the men were in quickly filled with smoke, but rescuers could not open doors buckled by the explosion.


Operator Mechanic Anthony Huntrod, 20, from Sunderland, and Leading Mechanic Operator Paul McCann, 32, from Halesowen, West Midlands, were dead by the time their shipmates reached them.


The deaths led to Armed Forces Minister Bob Ainsworth issuing an 'unreserved' apology in the House of Commons, after it emerged that the oxygen machine which exploded had been contaminated with oil.


A Board of Inquiry heavily criticised the Navy and the Ministry of Defence blamed 'systematic failings' for the tragedy.


Analysis by Matthew Hickley, Defence Correspondent:


The collision between two nuclear missile submarines appears to be a freak accident, which happened precisely because the vessels are so astonishingly stealthy.


Every minute of every day, since June 15, 1968, the Royal Navy has had at least one submarine out on patrol beneath the waves, carrying nuclear missiles capable of destroying whole cities.


Just one of these warships - known to sailors as 'boats' rather than 'ships' - carries more destructive firepower than the rest of the fleet, the RAF and the Army combined.


Yet they specialise in running away and hiding.


One they have left their base at Faslane in Scotland they slip quietly beneath the waves and patrol slowly and almost silently in the emptiest piece of ocean they can find. If the enemy cannot locate them, then he cannot destroy them - and so he dare not start a nuclear war.


In submarine warfare hiding means being quiet - too quiet for an enemy sonar system to hear and pinpoint you.


Both the British and French missile submarines are extraordinarily quiet, while their own sonar systems are designed to 'hear' the slightest sound from an enemy ship.


In this case both boats were on routine deterrent patrols, keeping their deadly missiles safe and ready to fire.


Both were listening hard for any other ships or objects to avoid, but each submarine was so quiet that the other was unable to hear it.


Only Britain, France and America are thought to operate such sophisticated and silent vessels. Russian boats are noisy by comparison.


But whereas British and American submariners routinely inform each other of roughly where their missile submarines are patrolling, to prevent just this kind of freak accident, it is understood there is no similar arrangement with the French.


As the French Navy generally has only one missile submarine on patrol at any one time, the British submarine had the remarkable misfortune to collide with the only vessel in the world which it is unable to detect, and knew nothing about.


[CV32: Emphasis mine]

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Some type of smoke curtain previous days? the story of the "falling container" in the mid-atlantic:

Le 6 février, la Marine nationale avait confirmé que Le Triomphant avait été victime d'une collision à son retour de patrouille, alors qu'il était en immersion, incident qui a provoqué des dommages sur son dôme sonar. Mais, à l'époque, vu qu'aucun bruit de submersible n'avait été détecté, l'équipage semble avoir d'abord cru qu'il avait heurté un conteneur immergé entre deux eaux. L'hypothèse était d'autant plus logique que la zone traversée par le Triomphant avait été balayée, les jours précédents, par une tempête./ On February 6th, Marine nationale had confirmed that Le Triomphant had been victim of a collision in the return of patrol, while he was in immersion, incident who caused damage on its dome sonar. But, at that time seen that no noise of submersible had been discerned, the crew first seems to have thought that he had hit a container submerged between two waters. Hypothesis was logical all the more as the zone crossed by the Triumphant had been swept, the previous days, by a storm.


The first echo of the new, dated february, 6, 2009, a day earlier than in the UK :

Mocking title "La dissuasion nucléaire française doit-elle craindre les conteneurs immergés ?

/Must the French nuclear dissuasion fear the submerged containers?":

On notera d'ailleurs qu'en 35 ans et quelques 400 patrouilles réalisées, c'est la première fois qu'un tel scénario se produit./They will note besides that in 35 years and about 400 accomplished patrols, it is the first time that such scenario occurs.


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I'm interested to know what the Harpoon maths are for this? Extremely Quiet vs. Extremely Quiet, that's for sure.


Excellent question. ;)


Vanguard SSBN (UK)

Signature: Small/Vquiet


Sonar 2054 hull array (passive range 4.3 nm pdet 50%)

Sonar 2044 towed array (passive range 6.0 nm pdet 50%)


Le Triomphant SSBN (France)

Signature: Small/Vquiet


DMUX 80 hull array (passive range 3.4 nm pdet 50%)

DMUX 80 flank array (passive range 4.3 nm pdet 50%)

Narama towed array (passive range 6.8 nm pdet 50%)

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Yes, it is important to remember that these are Harpoon's best, most optimistic guess at the possible detection range.


There are many modifiers and other conditions not taken into account by Harpoon which can make the detection range considerably less.

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From Times Online


From Times Online

February 16, 2009

French sub unaware it rammed Royal Navy vessel in mid-Atlantic nuclear crash

Charles Bremner in Paris, and David Brown


A French submarine was unaware that it had rammed and damaged a British nuclear sub in a mid-Atlantic collision until it was informed by the Royal Navy.


HMS Vanguard and the French submarine Le Triomphant were both carrying nuclear ballistic warheads when they crashed in the Atlantic this month.


Both navies said today that the collision had been unavoidable because the vessels were “running silently” to avoid detection by sonar.


Official inquiries have started in Britain and France into the incident which has raised concerns about the sharing of information between the navies.


The First Sea Lord, Admiral Sir Jonathon Band, said that the incident happened at low speed and none of the 250 crew on board the submarines was injured.


“Both submarines remained safe and no injuries occurred,” he said. "We can confirm that the capability remained unaffected and there has been no compromise to nuclear safety.”


The French Navy claimed this month that Le Triomphant’s bow sonar dome was probably damaged in a collision with a submerged shipping container while returning from patrol.


It discovered that it had hit a British submarine only after one of their regular exchanges of information with the Royal Navy.


HMS Vanguard returned to its base in Faslane, western Scotland, on Saturday with dents and scrapes on its hull after the collision that was reported to have occurred on February 3 or 4.


Le Triomphant took three days to limp home to port in Brest, northwest France, with extensive damage to its Thales DMUX 80 sonar.


The French Navy confirmed today that the collision took place in the Atlantic on a routine patrol and at great depth but would not reveal the location for routine security reasons.


Captain Jérôme Erulin said that such collisions were extremely unlikely but always possible between two submarines that are designed to evade detection.


“It was a brief contact at slow speed at the beginning of last week,” he added.


“These submarines are by definition very silent. The slow speed at the moment of the incident is their normal patrol speed. There was no human error.”


A senior Royal Navy source said today that the chances of two submarines colliding in the mid-Atlantic were “very, very small”.


“There has been no compromising of nuclear integrity whatsoever and neither has there been any reduction in our deterrent capability,” he said.


“Whatever speculation you have seen I can confirm neither of those has been affected."


The source said that submarines use “water space management” to separate themselves both geographically and in depth from other vessels when underwater.


“It is a well-established rule operated by Nato nations, and other nations when we exercise with them use the same rules, and they have built into them plenty of safety,” he said.


“It is remarkably difficult to detect a modern submarine with sonar and we work very hard with our own submarines, as do our allies, in making them as quiet as possible so they are not detectable.


“A submarine does not often go active – that is send out an echo – because it gives away a submarine’s position. So a submarine normally operates what we call passively, it does not transmit.”


Commodore Stephen Saunders, editor of Jane’s Fighting Ships, said: “This is a very serious incident. There are procedural issues that need addressing.


“We should not have submarines of friendly nations operating in the same area at the same time.”


Commodore Saunders said that although there were reports of collisions between submarines during the Cold War neither side would own up to them.


“Nuclear submarines would not normally operate together and I can think of no operational reason why they would operate together.


“I can only assume they were both on patrol so there would be no intention for them to be in the same space.”


Nato countries share details of submarine patrols and agree which areas and depths their vessels will operate in to avoid the risk of collision.


However, France has opted out of Nato’s military command so does not fully share information, although it normally provides some details of its submarine operations.


“I would be surprised if the French did not give an indication, or some sort of attempt to give an indication, about the extent of their operations,” said Commodore Saunders.


HMS Vanguard, which was launched in 1992, is one of four British submarines that carries the 16 Trident ballistic nuclear missiles with up to eight warheads. At least one of the submarines is on patrol at all times.


The 14,335-tonne Le Triomphant, which entered service in 1997, carries 16 nuclear missiles, with six warheads, and is one of four nuclear-armed submarines in the French fleet.


The incident is the most serious underwater collision since the USS San Francisco hit an undersea mountain in the Pacific head-on in 2005, killing one sailor and injuring 24 others.


Dr Liam Fox, the Shadow Defence Secretary, said that it was a relief that no one had been injured in the collision.


“For two submarines to collide while apparently unaware of each other’s presence is extremely worrying,” he said. “Hopefully lessons have been learnt to prevent anything like this ever happening again in the future.”


Nick Harvey, the Liberal Democrat defence spokesman, said: “The public entrust this equipment to the Government confident that all possible precautions are being taken.


“Now that this incident is public knowledge, the people of Britain, France and the rest of the world need to be reassured this can never happen again and that lessons are being learnt.”


Angus Robertson, the SNP leader in Westminster, said: “The MoD cannot hide behind operational secrecy and must make a statement on this as a priority.”


John Ainslie, co-ordinator of Scottish CND, said that the all nuclear submarines would immediately be confined to base.


The French anti-nuclear group Sortir du Nucleaire (Get Out of Nuclear) criticised the military authorities for taking several days to reveal the collision. “It seems clear that, once again, the first reflex of the nuclear lobby is to hide the truth,” it said.

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Well, Very Quiet ==> *0.5, Target Speed 0-6 knots ==> *1, Own Speed 0-8 knots ==> *1, Sea State 5-6 ==> *0.5, with the possibility of Shallow Water (VLF thru LF-MF) ==> *0.5. So for the bow sonar on the French boomer, 3.4 * 0.5 * 1 * 1 * 0.5 ( * 0.5) = 0.85 nm for the 50% detection range (or possibly 0.425 nm in shallow water). If the weather was REALLY ugly, you could cut that in half again, or possibly even eliminate any possibility of detection at all, particularly if the boats are running near the surface. For reference, at six knots you are covering a tenth of a mile per minute, so you've got less than ten minutes to make the detection, decide that it's not a whale with indigestion, decide that there's a collision hazard, communicate that fact, and take evasive action. Of course, at six knots you aren't very maneuverable anyway, and your target is itself almost a tenth of a mile long, and you will probably lose at least a minute of your margin to the sheer, blank, WTF?!? of it all ... :(

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So, they should have found each other?


If, as Brad suggests, the Vanguard was struck from the back (i.e. its blind spot), wouldn't this mean that the Vanguard had NO chance of detection?


How would the Vanguard's towed array affect this? Was the towed array deployed at the time?


Bear in mind that if the subs are traveling on the same path at the same speed, they can never collide.


Also bear in mind that there should be no real expectation that the statements officials are making about this are intended to be truthful.

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