(CNN) — United Airlines lifted a ground stop on all domestic mainline flights Sunday night after an issue with one of its key communication systems was resolved, two sources familiar with the incident told CNN.
Other computer glitches have hit airlines.
In October, United flights were delayed for hours because of a computer problem, causing a social media firestorm.
United said it experienced an issue with its weight reporting system that was later resolved.
In September, British Airways suffered a computer problem that caused delays and long lines at airports in the United States and Europe.
In August, Delta was forced to cancel around 2,000 flights after a major system failure. That came only a few weeks after an outage caused more than 1,000 cancellations at Southwest Airlines.