Flights began to leave the airports after 7 p.m. ET on Friday, but the ground stop — which prevents planes from landing at an airport — remained in place.
The smell was coming from Potomac TRACON, Duffy wrote, referring to a terminal radar approach control facility that manages air traffic for the Washington, D.C., Baltimore, Richmond, Virginia, and the Richmond-Charlottesville areas, according to the FAA website.
A spokesperson for the federal agency didn't respond to an emailed question clarifying how the smell was affecting traffic controllers on Friday evening.
Between 25% and one-third of all flights departing from the four airports affected were delayed after the ground stop.
