FAA router failure grounds 11,000 flights before airspace reopens

The Federal Aviation Administration declared a nationwide ground stop Friday afternoon after routers handling air traffic control data became overloaded and began returning inconsistent readings, forcing the agency to shut down domestic airspace. More than 11,000 flights were delayed or canceled, according to FlightAware, with 3,500 aircraft already airborne when the order took effect.

Transportation Secretary Sean Duffy confirmed the airspace reopened at 8:15 p.m. Eastern and said the root cause had been identified: data inconsistency from overloaded routers across all Air Route Traffic Control Centers. Homeland Security Secretary Markwayne Mullin said preliminary findings showed no indication of a hostile attack, describing it as a telecommunications outage.

Duffy used a White House briefing to call on Congress to fund a full replacement of the existing air traffic control system, which he described as "incredibly old." The stoppage follows FAA workforce reductions of roughly 2,000 controllers and comes less than a year after a mid-air collision at Ronald Reagan Washington National Airport killed all 67 aboard.