The US Federal Aviation Administration has implemented safeguards to prevent database errors that grounded flights in January.

On January 11, a Notice to Air Missions (NOTAM) system outage impacted some 11,000 flights in the US. In the days after the incident, the FAA issued a statement explaining the cause:

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 agency has so far found no evidence of a cyber-attack or malicious intent. The FAA continues to investigate the circumstances surrounding the outage.

The FAA made the necessary repairs to the system and has taken steps to make the NOTAM system more resilient. 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.

According to Reuters, the FAA has implemented “a one-hour synchronization delay for one of the backup databases. This action will prevent data errors from immediately reaching that backup database.” The FAA also said it “now requires at least two individuals to be present during the maintenance of the (messaging) system, including one federal manager.”