FAA finds outage was unintentionally caused by contractors

The Federal Aviation Administration (FAA) announced Thursday that contractors "unintentionally" deleted files used for its alert system, leading to the outage that delayed or cancelled thousands of flights earlier this month.

The FAA said in a statement that the contract personnel were working to correct synchronization between the Notice to Air Missions (NOTAM) system's primary live database and its backup one when they deleted the files. The agency said that there is no evidence of a "cyber-attack or malicious intent," adding that they are continuing to investigate the outage.

"The FAA made the necessary repairs to the system and has taken steps to make the NOTAM system more resilient," the FAA said in a statement. "The agency is acting quickly to adopt any other lessons learned in our efforts to ensure the continuing robustness of the nation’s air traffic control system."

The FAA temporarily suspended all domestic flight departures earlier this month as it worked to fix an issue with its NOTAM system, causing widespread delays and cancellations. At the time, the FAA said a "damaged database file" was likely the root cause of the outage.

The NOTAM system notifies pilots with real-time information about flight hazards. After the system suffered an initial outage, officials decided to launch a complete reboot of the system the following day.