Updated 8:30 a.m.
Domestic flights out of Denver International Airport resumed operations Wednesday morning. But travelers could continue to see disruptions throughout the day, the airport said in a tweet.
“Passengers should check their flight status with their airline before heading to DEN,” the airport said. “We expect many delays and some cancellations throughout the day.”
The disruptions stemmed from an outage of the Federal Aviation Administration’s Notice to Air Missions system, which is used to communicate safety information to pilots and air traffic controllers. The system has been in use for over 70 years, according to NPR.
“NOTAMs are what the FAA uses to communicate real-time information to pilots and air traffic controllers about everything from weather to airport construction,” NPR reported. “Pilots might receive NOTAMs about closed runways, large flocks of birds, a plume of volcanic ash, ice on a runway, or lights on tall buildings and towers.”
The system went down overnight Tuesday, according to the FAA. The agency issued a nationwide ground stop for air travel through 7 a.m. Wednesday in response.
Airlines at DIA canceled at least 55 flights Wednesday morning, according to the flight tracking site FlightAware. Southwest Airlines made up the bulk of canceled flights. Roughly 300 more flights had delays.
The Colorado Springs Municipal Airport experienced 20 delayed flights.
The FAA did not give a reason for the nationwide system failure.
“We continue to look into the cause of the initial problem,” the agency tweeted.
United Airlines said in a tweet that it was offering travel waivers to affected passengers.
The original story continues below.
Flights across the nation, including in Colorado, experienced delays on Wednesday morning due to a computer outage at the Federal Aviation Administration.
More than 300 at Denver International Airport saw delays, according to the flight tracking website FlightAware. At least 45 were cancelled — a majority through Southwest Airlines.
Airports in Colorado Springs and other parts of the state also saw delays due to the technical failure.
“The FAA is working to restore its Notice to Air Missions System following an overnight outage,” the agency tweeted early Wednesday. “We are performing final validation checks and reloading the system.”
Departures will resume around 7 a.m. Mountain Time Wednesday, according to the FAA. Some airports were already seeing departures due to air traffic congestion, the agency said.
Flights already in the air during the outage are safe to land.
This is a developing story and will be updated.