Computer Outage Leads to Airline Outage

United flights around the globe sat on the tarmac for 2 hours this morning after a computer malfunction effectively shut down the world's second-biggest carrier. The midmorning glitch affected an unknown number of flights, Bloomberg reports, before techs traced the trouble to the systems that weigh planes, check their balance, and monitor the opening and closing of aircraft doors.

An analyst attributed the situation to a "massive failure," and gridlock ensued at O'Hare, United's main hub, because departing flights were unable to leave their gates. Passengers trapped on the tarmac were eventually allowed to deplane at the international terminal. The airline said it didn't know when service would return to normal.  (More United Airlines stories.)