A controller tested positive.
https://www.seattletimes.com/nation-...ests-positive/
The controller was found to have the virus Wednesday, the Federal Aviation Administration said in a statement on Thursday. As of 9:08 a.m., airlines had canceled 463 flights to and from the airport, or more than 35%, according to the flight-tracking website FlightAware.The FAA is transferring partial control of flights to a nearby facility that oversees traffic in that region. While most airports with commercial service have towers, airliners are allowed to land without the assistance of tower controllers by following special procedures.