Couple things.

1) the source of this is a new book by Eric Schlosser, who wrote Fast Food Nation. This is his take on reading 50-year-old documents.

2) Here's the money-quote:

" The only thing standing between us and an explosion so catastrophic that it would have radically altered the course of history was a simple electronic toggle switch in the cockpit, a part that probably cost a couple of bucks to manufacture and easily could have been undermined by a short circuit—hardly a far-fetched scenario in an electronics-laden airplane that's breaking apart."

In other words, bad shit would have happened if the plane had broken apart and the arm switch in the cockpit had spontaneously fritzed. 'cuz if it had fritzed before the plane broke up, the pilots would have been all "holy shit we don't just got live nukes on board, we've got live, armed nukes on board." If it had fritzed after the plane broke up, nothing would have happened because the weapons still wouldn't have been armed.

In other words, a toggle switch saved North Carolina. But when you look at it that way, toggle switches save everything. There are toggle switches on the Space Shuttle. There are toggle switches in Fukushima. There are toggle switches on drawbridges.

The system worked. Was it hairier than anybody wanted? Absolutely. Betcha they didn't do it that way again. Nonethless, here's what a Mk39 Mod 3 looks like after falling out of a plane:

http://upload.wikimedia.org/wikipedia/commons/b/b0/Goldsboro...

Look - up until 1976, the "nuclear launch codes" were twelve zeroes. We averted disaster through sheer force of will. So many terrible, terrible things could have happened that would have ended civilization in an eyeblinkc... but they didn't. And on that scale, bombs falling out of a B-52 and not blowing up is pretty low on my oh-shit meter.