But maintaining a remote fail-safe system is trickier when dealing with employees' devices, which store their own apps, photos and other information.

WSJ: Danger-to-Go: Mobile Devices in the Workplace

Now Israel's airport authority is trying to explain how the knife got through what is vaunted as a fail-safe security system.

ECONOMIST: Taking a harder line

In recent years, though, questions have mounted over whether the system is fail-safe.

NEWYORKER: Trial by Fire

Mr. Hayward and BP have taken the position that this tragedy is all about a fail-safe blow-out preventer (BOP) failing, but in reality the BOP is really the backup system, and yes we expect that it will work.

WSJ: The Oil Disaster Is About Human, Not System, Failure