What's the biggest most important event that genuinely happened "in the nick of time"

Nick of time in this scenario= 30 seconds or so.

In movies it’s common for event A to occur just a couple of seconds before event B happens, thus nullifying the massively important thing that would have happened if event B had taken place. (e. g bomb in the White House). What is the most important event that can really to have been foiled by something that had it happened 30 seconds later would have failed?

Well, Stanislav Petrov correctly guessed that when the Oko nuclear early-warning system reported that a missile was being launched from the United States, it was a false alarm. He did not launch a retaliatory strike, thus preventing World War III.

One defective switch averted East coast nuclear disaster in 1961.

http://abclocal.go.com/wtvd/story?section=news/local&id=9258613

The Soviet submarine commander during the Cuban Missile Crisis who decided not to launch attacks against U.S. blockading warships – hell of a decisive moment. I don’t know what the time-frame was: seconds, minutes, hours?

How about the near-invalid who was brought in to the Senate in a stretcher to cast what might have been the decisive vote in the impeachment trial of Andrew Johnson. (Not guilty.) Again, I don’t know the time-frame, but it was certainly a damn close call.

I think it’s going to be tough to top any of the cases where the outbreak of nuclear war came down to a minute or so of uncertainty and a correct decision (sometimes against the facts). Maybe we could concede that and find the next-biggest thing?

Just came in to see how long it took to get to Petrov. Well done, all.

Iirc there were a couple of occasions where european explorers were saved from natives by a timely eclipse. A tsunami or two saved Japan from invaders. Hitler was saved numerous times from assassination by chance events. James Doohan, of Star Trek fame, was saved from being killed on d-day by a cigarette case in his pocket.

This might come close to the top of the list. Either a less driven or less erratic leader would have changed the course of the war considerably.

Apollo 11 landed with about 25 seconds of fuel left.

Which would have only delayed the first landing. They were prepared to abort, dropping the landing section and scooting back to orbit in the ascent stage. It would have been a bummer but likely only a short setback.

Columbus was the one who pulled this trick, when he was shipwrecked in Jamaica on his fourth voyage. The locals had refused to continue bringing food to his crew (mainly because they were jerks), until Columbus threatened to make the moon turn red -which it did on cue.

Mark Twain used this device in A Connecticut Yankee in King Arthur’s Court, but I am unaware of any other instances when it was used in real life.

That is an interesting and scary story that I have never heard before. However, as I read it, what averted the disaster was that that one switch, unlike all the other fail-safes supposedly in the system, was not defective, even though it quite easily could have been. Everything else went wrong, but that switch held.

I caught the last green light on the way home from eating lunch at Taco Bell, arriving home just in time to avert a scene of carnage beyond description in this delicate forum.

I pulled out.

Also Tintin in * Prisoners of the Sun*

And the Englishmen in * King Solomon’s Mines *

Also Tintin in * Prisoners of the Sun*

And the Englishmen in * King Solomon’s Mines *

Nm

Seth MacFarlane of Family Guy fame owes his life to an assistant screwup that made him a bit late to his flight that would have crashed on 9/11. Not seconds though, so not really “nick of time” I guess.

President Roosevelt nearly getting torpedoed.

How about the Icelandic island of Heimaey, in which the volcano Eldfell erupted, and the local townspeople managed to spray the approaching lava with seawater <!> until it cooled and diverted, saving the fishing village.

In reverse: in the Battle of Isandlwana in the Anglo-Zulu War of 1879, an eclipse happened in the middle of the battlefield. The Zulus took this as a favorable sign – they liked to fight at night – and pressed on their efforts.

Also the opposite of the OP: the Burke and Wills Expedition.