FAA outage caused by personnel who 'failed to follow procedures'

FAA said data file was damaged, leading to delays and cancellations of thousands of flights

The Federal Aviation Administration's system-wide outage that led to mass flight delays and cancellations on Wednesday was the result of the actions of personnel who the agency said had "failed to follow procedures." 

"Over the past 36 hours, the FAA has been conducting a preliminary analysis into the NOTAM [Notice to Air Missions] system interruption," it said in an emailed statement to FOX Business. 

"The agency determined that a data file was damaged by personnel who failed to follow procedures," the FAA said Friday. "The system is functioning properly and cancelations today were below 1%."

ABC News, citing a senior FAA official, reported Thursday that the ground stop order that paused all domestic departures and the FAA systems failures on Wednesday appeared to have been the result of a mistake that occurred during routine schedule systems maintenance. 

FAA OUTAGE FALLOUT: HUNDREDS OF FLIGHTS DELAYED, CANCELED DAY AFTER MELTDOWN

A Southwest Airlines passenger jet takes off

A Southwest Airlines passenger jet takes off from Chicago's Midway Airport as flight delays stemming from a computer outage at the Federal Aviation Administration brought departures to a standstill across the U.S. on Wednesday.  (AP Photo/Charles Rex Arbogast / AP Newsroom)

The official noted that the engineer "replaced one file with another," not realizing a mistake was being made. 

It remains unknown whether a disruption of Canada's NOTAM system the same day was connected with the U.S. The official noted to the network that Canada has a more modern system and a fraction of U.S. air traffic

Passengers walk past a flight status board

Passengers walk past a flight status board in Terminal C at Orlando International Airport in Florida that shows many delays on Wednesday after the FAA grounded all U.S. flights earlier in the day.  (Joe Burbank/Orlando Sentinel/Tribune News Service via Getty Images / Getty Images)

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U.S. air travel returned mostly to normal on Thursday after more than a million travelers were inconvenienced by the outage in the safety-alert system. 

Transportation Secretary Pete Buttigieg

Transportation Secretary Pete Buttigieg appears during an announcement at O'Hare International Airport in Chicago on Nov. 21, 2022. (Christopher Dilts/Bloomberg via Getty Images / Getty Images)

Transportation Secretary Pete Buttigieg said that when the system first broke down Tuesday night, a backup system went into effect. However, a complete reboot of the main system Wednesday morning failed.

He promised a thorough examination to avoid another major failure.

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"Our immediate focus is technical — understanding exactly how this happened, why the redundancies and the backups that were built into the system were not able to prevent the level of disruption that we saw," Buttigieg told reporters.

The Associated Press contributed to this report.