United Airlines resumed normal operations on Tuesday after a temporary network outage hampered its website and airport functions.
The airline said in a statement that the outage caused flight delays and cancellations. As a result, United said it was allowing passengers affected by the incident to cancel and rebook flights without penalty.
The airline's website was also back up and operating after the earlier outage.
United has had problems integrating some operations after the 2010 merger with Continental Airlines.
In March, United adopted the reservation system of Continental, triggering computer problems that caused flight delays, faulty kiosks and jammed phone lines.