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Comment by mootothemax | Hacker News Reader

Is much the same now, the UK doesn't have launch codes and operates the whole thing as a sort of dead-man's switch, apparently partly based on if the Today program has been broadcast on Radio 4.

Are you sure you're not confusing that with nuclear submarine commanders checking that BBC Radio 4's still broadcasting as part of their "is the country still there" checks?

From http://en.wikipedia.org/wiki/Letters_of_last_resort :

According to Peter Hennessy's book The Secret State: Whitehall and the Cold War, 1945 to 1970, the process by which a Trident submarine commander would determine if the British government continues to function includes... establishing whether BBC Radio 4 continues broadcasting

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Not really a confusion: if the letter of last resort (sealed orders to be opened in the event the Government is destroyed) says "launch the nukes", you do have a sort of dead man's switch, assuming the sub's captain follows the orders.

It's certainly true that the UK has a sort of dead-man's-switch (depending on exactly what the letter of last resort says).

But I presume that there is also a more active communication method as well. If the Prime Minister wanted to launch the nukes then he would be able to send a message to the subs and launch immediately.

I've always understood "dead man's switch" to literally mean something operating without human intervention. Probably explains the confusion!

That said, the options available to the commander do leave some room for interpretation:

- retaliate with nuclear weapons;

- not retaliate with nuclear weapons;

- use his own judgement; or

- place the submarine under allied country command - if possible

"I've always understood "dead man's switch" to literally mean something operating without human intervention.... That said, the options available to the commander do leave some room for interpretation".

Yeah, hence my gutless hedging with "sort of".

Maybe "failsafe" would be a better term, like in the film of that name, where the bombers are instructed to ignore any order to abort once they pass a particular point. (Actually, "fail-deadly" would be more accurate: why wasn't the film called that?)

I also find it interesting that the effectiveness of these orders rely purely on the captain's sense of duty, as (assuming the system has worked correctly) the only other person who knows what they say is dead.

It wouldn't be opened by the captain alone. I don't know about the US procedures, but in the Soviet army/navy the sealed orders would most likely be opened by a trio of the captain, deputy and the 'political officer'; and captain deciding to do otherwise would be a valid reason to remove him from command on the spot, if the other two disagree.

Those options were not given to the sub commander, they were options given to the Prime Minister to include in the letter. Which of them went into the letter, and under what circumstances the Prime Minister advised they be followed was a matter for the Prime Minister to decide.

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