Airplane safety contractors deleted files that led to massive disruption across US

An investigation discovered that the debacle was the result of contractors mistakenly deleting files in the Notice to Air Missions database.

"A preliminary FAA review of last week's outage of the Notice to Air Missions (NOTAM) system determined that contract personnel unintentionally deleted files while working to correct synchronization between the live primary database and a backup database," the FAA wrote in a statement.

They added that there has thus far been "no evidence of a cyber-attack or malicious intent," however the investigation is ongoing.

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

As Yahoo! News reports, the contractors' mistake, which occurred around 3:30 pm EST on January 10, caused the FAA to push flights back that day, and fully pause all domestic departures the following morning.

At 7:15 am on the 11, the FAA ordered all airlines to pause flights within the US until 9 am, however by 8:15 am departures resumed at Newark and Atlanta airports due to "air traffic congestion."

Ten minutes before 9 am the ground stop was lifted, and operations gradually resumed across the country.

Following the incident, Transportation Secretary Pete Buttigieg questioned how the NOTAM system was compromised.

"A critical system like this has a lot of redundancy built into it with backups," he said, "so we need to understand why with all of that redundancy it still rose to the level that there had to be a ground stop."

The NOTAM system is run by the FAA and provides real-time updates to airlines and their crews regarding weather, infrastructure, and anything else that could impact flights.