Flight cancellations and delays are rising in thousands at airports nationwide following an outage in the Federal Administration Aviation’s (FAA) Notice to Air Missions system. 

According to the flight-tracking aviation company FlightAware, 6,400 flights in, out, and within the U.S. were delayed as of 10 a.m. CDT, and over 1,000 flights in the country were canceled. 

Major domestic airlines based in Dallas-Fort Worth, such as American Airlines and Southwest, are experiencing sweeping changes due to the FAA computer system outage, which occurred overnight. As of around 10:15 a.m CDT, nearly half of Southwest Airlines flights were delayed, according to FlightAware, amounting to 45 percent of its overall flights. 

Affiliated with the U.S. government, the FAA is the nation’s largest transportation agency which regulates all aspects of national civil aviation, including commercial air transportation and air traffic operations. 

Following a glitch in the FAA’s computer system late last night, the airspace “ordered airlines to pause all domestic departures until 9 a.m. to allow the agency to validate the integrity of flight and safety information,” according to a tweet on behalf of FFA.

According to the FAA’s website, the Notice to Air Missions system, which has existed since the last century, communicates “information essential to personnel concerned with flight operations, but not known far enough in advance to be publicized by other means.”

The FAA said that following the glitch, the Notice to Air Missions system had failed and could not process new information, acting as a safety concern for national air traffic conditions. 

The outage last night carried into early morning today, producing a ripple effect, and leading to a nationwide pause on domestic flights, also known as a ground stop, issued by the FAA, becoming the first ground stop in the United States since the September 11, 2001 terrorist attacks.

At around 4 a.m. CDT, the FAA lifted the nationwide ground stop. Officials say as airline companies reel from the delays caused by the nationwide pause, further delays and cancellations will increase. 

According to FlightAware, 636 flights into, out of, and within the United States have been delayed in the Dallas-Fort Worth International airport, in addition to 57 flight cancellations today. At Dallas Love Field Airport, which is smaller than Dallas-Fort Worth International, 215 flights into, out of, and within the United States have been delayed and 38 flights have been canceled. 

The reason behind the system outage remains unknown. However, according to a statement by the FAA, “the agency (FAA) continues to look into the cause of the initial problem.”