A system-wide computer failure forced Southwest Airlines to ground its entire fleet of airplanes preparing for departures late Friday, and at least 57 flights had to be cancelled even after service was fully restored hours later, a company spokeswoman said.

Michelle Agnew told The Associated Press that 43 of the cancellations were flights scheduled for late Friday night departures in the western half of the United States. The other 14 were Saturday morning flights scattered across the U.S. because crews were not able to get to airports in time to make the scheduled takeoffs.

An estimated 250 flights _ most of them on the West Coast _ were grounded at least temporarily Friday night. The glitch impaired the airline's ability to do such things as conduct check-ins, print boarding passes and monitor the weight of each aircraft.