The US Federal Aviation Administration (FAA) ordered a nationwide halt to all flight takeoffs due to communication issues affecting air traffic control centers.
The FAA cited “extraordinary circumstances and safety considerations” for the grounding, which initially stemmed from a problem with network routers, believed to have originated at Chicago Midway International Airport before spreading across the country. This unprecedented measure, which also led to the suspension of all flights to the US from Eurocontrol member countries at America's request, resulted in nearly 7,000 flights being canceled or delayed. While the Federal Bureau of Investigation (FBI) deemed a cyber attack or criminal activity unlikely, investigators are looking into a potential software system update as the cause. Flights already in the air were permitted to land, but no new departures were allowed.