BREAKING: U.S. Flights Grounded Following FAA Computer Glitch

Flights across the U.S. have been grounded due to a computer glitch with the Federal Aviation Administration's systems, according to reports.

The FAA is working to restore its Notice to Air Missions (NOTAM) system, which alerts pilots of potential hazards.

"The FAA is working to restore its Notice to Air Missions System," it posted on Twitter earlier. "We are performing final validation checks and reloading the system now. Operations across the National Airspace System are affected. We will provide frequent updates as we make progress."

A total of 21,464 flights are scheduled to depart airports in the U.S. today, according to data from Cirium, with nearly 2.9 million seats available on these departures.

American Airlines has the most departures from US airports today (4,819), followed by Delta Air Lines and Southwest Airlines.

The FAA in a later notice said it had ordered airlines to pause all domestic departures until 9 a.m. Eastern Time to "allow the agency to validate the integrity of flight and safety information."

Shortly before 9 a. m. it lifted the ground stop, posting on social media: "Normal air traffic operations are resuming gradually across the U.S. following an overnight outage to the Notice to Air Missions system that provides safety info to flight crews. The ground stop has been lifted. We continue to look into the cause of the initial problem."

United Airlines told customers that they may continue to see some delays and cancellations as it works to restore its schedule, and that they should check its app or website.

The airline also activated a travel waiver for any customers who needs to change their plans, including offering refunds for customers who no longer want to travel.

The U.S. Travel Association said the "catastrophic system failure" caused 3,000 flight delays and several hundred cancellations across the country, and called for significant upgrades to be made.

"Americans deserve an end-to-end travel experience that is seamless and secure," said president and CEO Geoff Freeman in a statement. "And our nation’s economy depends on a best-in-class air travel system. We call on federal policymakers to modernize our vital air travel infrastructure to ensure our systems are able to meet demand safely and efficiently.”

Airlines for America said it was working with the FAA and awaiting further information regarding when these issues will be resolved. It has urged travelers to download their airline’s app, visit the carrier’s website and ensure their contact information is accurate on travel records.

This breaking news story is being updated throughout the day