It was a in bad weather, huge waves (Golfe de Gascogne), and the dirty little secret about super smart detection/weaponry gizmos, whether airborne, submarine, you-name-it, is just: they only work on a quiet, sunny, midsummer morning.
Both subs would be cruising at 600m depth, because that's the maximum they can, and deeper is stealthier. No need to invoke coincidence for the depth match, it's a design thing, all recent boomers cruise a 600m, full stop.
Both subs would be cruising at 4 knots (arguably a ridiculously low speed, but absolutely silent, and that's what boomers are for), which greatly limits the potential for damage. As for why the Vanguard had to be towed, I can only speculate one reason: it was hit by the rear, and it damaged a rudder.
The Triomphant, with just a big chunk of fiber glass blasted, lost basically no capability save torpedo launching (and this is probably the greatest risk we came close to: an idle torpedo in a launch tube could have gone off and blasted the sub from the inside, exactly kursk-style, but actually a dozen such incidents in western navies over the past 50 years never triggered any torpedo, only russian torpedoes are seriously dodgy).
Could the crews have prevented the collision ? If they were not on particular alert, not picking anything is the most likely outcome. And if any did, the procedures in place would not actually help, because they are designed on the idea that a collision course is very unlikely during an encounter. Procedures would be: make no move, because any rudder move could have you detected, make even less noise, and grab the best audio signature you can for the navy's database. If the signal is weak (likely), it takes longer to determine that it is a collision course, than for the collision to happen...
The most likely outcome, aside from the embarrassment and the bill, is that NATO countries will start "boxing" the boomers just like hunter-killers, and share the box data. Boomers will probably have much larger boxes, like 1000-NMI wide, overlapping with hunter boxes (boomers have always known about the hunter boxes to avoid them except for planned exercise). NATO countries only total about 22 boomers, so 15 at sea at any time, two thirds of them US now stationned only on the Pacific, so this should be pretty easy and not involve any loss in deterrence capability and independence (that is, for France versus the anglo, there is no independence of the UK vs the US). Pierre
Noise constraints dictate that unless they have a clear emergency (like a torpedo fired at them), they move real slow, turn real slow (like: take 50 nmi to make a U turn), and move real tricky (like: you don't actually make a U turn, you make an elaborate movement which looks like you change you mind six times in the process, with five different speeds all along, just in case someone was listening, the reason being that if you make a simple geometrical trajectory and someone hypothesises it, he can infer from the doppler data on your noise spectrum, all you spectrum characteristics - know exact speed, so get to the original unshifted frequencies in your spectrum, etc, etc...)
This is usually sumed up by "fart slow". Very boring also. The only place with some action on board a boomer, is the collection of porn tapes in the mess.
So regarding the present fuck-up, the answer is: save a detection of torpedo launch, or a very clear signal of constant angle (unlikely in bad weather from such subs), the doctrine was to keep listening whatever anyone had heard (or not), while globally going straight forward, so if the encounter was by change on a collision course in 2D, it was a goner from the start. No more complicated than that. Pierre
When you say 1/23000 yrs, that would be with one sub each ? or for one given sub with two subs per navy ? then it's 1-(1-1/23k)^4 for all four subs ? Pierre
US boomers are all in the pacific now. russians are in the arctic along their own coastline. the chinese have only one 20-yrs old boomer, and there are so many us hk stalking it when it sets sails, that its position may be leaking to google placemarks near real time nowadays. This incident could only ever happen between france and uk in the present setup of strategic forces. Pierre
Now the following computation: average speed: 4knots = 4 nmi/hour ~ 7.5 km/hour effective "collision" section = 20 meters (ship breadth, all @600m depth) area combing speed: 0.15 sq km / hour, or over 3 sq km / day.
Total patrol area in the north atlantic + transit lanes = a few million sq km. Lets say there are constantly about 4 boomers in there (only boomers count, they dodge their own HK because they know where they are). That's two boomers of a different country for each boomer of first country (let's forget non existent russians, and assume boomers of one country are more or less boxed).
What is the average time between intercepts considering the entire fleet of 4 subs ? (we assume even if they detect the encounter, they don't deviate from current trajectory) Pierre
I get to about 100 000 days on average between collisions, which is 273 years. Not such a large number, but still, it comes a bit early when such patrols have been going on since "only" 40 years. Now, of course a little bit of "lets veer just a little bit toward this weird noise so we get a clearer signal" might help a lot in bringing the numbers down (boomers are not supposed to do this, but you know, it gets so boring down there...) Pierre
