There wasn't anything particularly sinister about the Notice to Air Missions (NOTAM) outage that prompted the Federal Aviation Administration to ground US flights on Wednesday — it appears to have been a relatively simple glitch. As part of its early investigation, the FAA has determined that the outage was prompted by a "damaged database file." The agency is still working to identify the exact causes and prevent repeat incidents, but says there's still "no evidence" of a cyberattack.
The FAA grounded all domestic departures in the US on Wednesday morning after the NOTAM system failed the afternoon before. This was the first such failure in the country, and it prompted hundreds of delays that took hours to resolve. NOTAMs provide important information about potential problems along a flight's path, such as runway closures and temporary airspace restrictions.
Update 6: We are continuing a thorough review to determine the root cause of the Notice to Air Missions (NOTAM) system outage. Our preliminary work has traced the outage to a damaged database file. At this time, there is no evidence of a cyber attack. (1/2)
— The FAA ✈️ (@FAANews) January 11, 2023
The initial findings may be reassuring for those concerned the outage may have stemmed from another critical infrastructure hack. However, it still leaves some unanswered questions about the fragility of NOTAM in the US. A single corrupted file was apparently all it took to disrupt flights nationwide for over half a day — whatever redundancy was in place clearly wasn't enough.