Southwest Airlines cancelled or delayed about 250 flights late Friday and early Saturday due to a system-wide outage of computers used to dispatch aircraft.
The Dallas-based airline said 43 overnight flights were cancelled as a result of the outage, which began around 11 pm EDT on Friday and lasted until about 3 am Saturday, said a Southwest Airlines spokeswoman.
Another 14 morning flights were cancelled due to "flight crew availability and aircraft positioning" after the outage ended, she said.
Most of the cancellations affected routes in the western United States. Flights that were already airborne were not affected by the outage, while aircraft on the ground were held back, she said, adding that the cause of the computer failure was unknown.
Southwest, which operates some 3,400 flights daily, said in a statement on its website that its "systems are working at full capacity."