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Submarines Collide, Questions Abound

Posted by Bob Kohm on February 17, 2009

It’s a big ocean. There aren’t that many submarines in it.

There are even fewer nuclear missiles subs (SSBNs) in it. The US has the largest contingent with 10 Ohio boats  assigned (with 4 usually on patrol at any one time), the Brits and French have four each, and the Russians sometimes send a few into the North Atlantic but generally keep them much closer to home in the Barents Sea.

Somehow, on the night of February 3-4, one of those four French subs found one of those four British subs and crashed into it, placing a big chunk of each nation’s strategic nuclear deterrent on the shelf for the foreseeable future. It’s almost unbelievable. Actually, it’s totally unbelievable; let’s explore why.

To say that these subs had the entire Atlantic to operate in would be incorrect; SSBNs have “patrol boxes” based on factors like their missile ranges, security requirements, transit times to and from port, etc.¬† which greatly reduce the area of ocean they can operate in. The French L’Triomphant class carry up to 16 M45 missiles with a range of 6000km, the British Vanguard boats sport 16 US designed Trident II missiles with a classified range known to be upwards of 7300km, so that is the first stricture on their patrol areas– they must be maintained within range of their primary targets, assumed to be European Russia and the Middle East. The French doctrine also is rumored to demand that their SSBNs be maintained within land based air cover. Combine those strictures– a flight radius of 5000-5500km of Tehran and Moscow and under land based air cover– and you can see why the widely assumed operating area for French SSBNs has always been the western Bay or Biscay and its approaches in the East Atlantic. The British boats, given the much longer range of their missiles, operate considerably to the northwest of that area.

Another limit to patrol areas is an Agreement by NATO on carving out operating areas for member subs. The Atlantic is broken up into sectors, with those sectors being assigned to the US, British, Norwegians, Dutch, Germans and Belgians, all of whom have operated subs during the last thirty years. They are not exclusive operating zones, but if the boats from one nation crosses or operates in the zone of another they are expected to notify the “owner” nation. The zone system wasn’t put into place to prevent collisions; it was put into effect so that if a Dutch sub picks up a sub operating in its AO on passive sonar it can be reasonably sure that it was tracking a Soviet/Russian sub, not an American 688 or British Trafalgar. Notably missing from the hunting preserve list is France, who maintains itself outside the NATO military command structure and thus refuses to acknowledge this orderly system or notify other allied nations of the transit of their subs.

So, we’ve greatly carved down the swath of available ocean that these boats operate in. That still leaves not only an incredibly huge tract of ocean relative to the size of these subs, but an incredibly huge swath of ocean multiplied by the operating depth of these submarines. Subs, of course, operate in two dimensions– the incredibly unlikely event of the two boats being in the same geographic place doesn’t alone give us a collision– they must also both be operating at depths basically in the same sixty foot band out of the roughly 1500 foot operating ranges of these boats.

So, even though we can’t say these two subs had an entire ocean to play in, we can safely say they had a huge amount of water, both in area and volume, with which to miss each other. To put in in perspective, let’s totally clear the airspace over the United States from Maine to Florida to Cleveland. Now let’s randomly put two airplanes in the skies in that area… and watch them smash into each other. That’s a decent example of what we’re talking about in this collision… only with 48 nuclear warheads and two nuclear powerplants involved.

Want to know the most disturbing bit of all of this? From photos taken of the two subs, it is apparent that the French L’Triomphant crashed nose-first into the side of HMS Vanguard, t-boning her in the kind of accidental collision you’d see if someone ran a red light. What makes that quite so crazy in this instance (just in case we need more crazy here…) is that the bow of the submarine is where her sonar dome is located. Assuming that these subs were both operating under passive sonar– basically just listening to the water in front of and around them with their hydrophones– the one place above all others that the L’Triomphant should’ve had an excellent picture of the water around them was right in front of the bow. Granted the Vanguard is an extremely quiet ship and the L’Triomphant a bit less so but still quiet, but still… they didn’t know they were about to hit Vanguard? While not impossible, it is highly unlikely barring the sonar operators being asleep at their consoles or the sonar being degraded in some fashion. Quite strange.

So, how did these two boats with different operating areas defy all odds and crash into each other under the Atlantic Ocean on the night of February 3-4? It is believed that this collision occurred well to the northwest of the assumed French patrol area, probably within the British patrol box. What was the French sub even doing there, at the very edge or even outside the range of its missiles from their primary targets? Given the secrecy with which SSBN operations are handled, we may never know, or more likely we probably won’t know until twenty years from now when some retired Royal Navy captain spills the beans in a book, much as American and Russian captains and civilian contractors have been doing over the past five years with regard to US-Soviet submarine games and disasters.

That being said, do you really think this was compeltely a fluke occurrence, against astronomical odds, of two subs being in the same place at the same time, one of them with no discernible reasons for being there?

Me either.

Last week satellites collided against huge odds, this week it’s nuclear missile subs. What crashes next week?

Posted in European Union, NATO, Nuclear Weapons, Submarines | 1 Comment »

 
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