Not to dismiss the potential severity of the North Carolina incident, but it seems like we're more likely to bring a nuclear apocalypse upon ourself through human error than engineering. Excluding the Cuban Missile Crisis, there have been a number of incidents where military men simply stayed calm in situations where radar and other equipment suggested every indication of an attack. Thankfully the psychology of mutually assured destruction kept those with their finger on the trigger thinking, "No, this cannot be right." I think the most recent was in 1995 when a Norwegian science experiment was mistaken for an incoming missile from the United States. Luckily the incident never escalated to Boris Yeltsin; had he been drunk at the time, who knows what part of the country would be a radioactive crater.This is not due to luck, it's due to the fact that nuclear weapons are pretty goddamn tough.