Key keywords: FAA, DC region flight halt, Potomac TRACON, strong odor incident, air traffic controller safety, US national capital airspace disruption, flight ground stop, HVAC system failure, hazmat inspection On Wednesday afternoon, the U.S. Federal Aviation Administration (FAA) issued an immediate full ground stop for all arriving and departing flights across the Washington D.C. metropolitan region, after on-duty staff at the Potomac Consolidated Terminal Radar Approach Control (TRACON) facility reported a sudden, pungent unknown odor spreading through the main operations room. The Potomac TRACON is one of the busiest air traffic control hubs in the U.S., responsible for managing all low-altitude airspace across a 8,000-square-mile area covering D.C., northern Virginia, central Maryland, and parts of West Virginia and Delaware. It oversees operations for three major commercial airports: Ronald Reagan Washington National Airport, Washington Dulles International Airport, and Baltimore/Washington International Thurgood Marshall Airport, plus more than 30 smaller general aviation airfields, handling an average of 7,200 takeoffs and landings per day. Following the odor report, the FAA immediately activated its emergency response protocol, pausing all new flight departures from regional airports and rerouting incoming flights to avoid the affected airspace while staff were temporarily evacuated from the control facility. Local fire department hazmat teams were dispatched to the site to conduct air quality testing, and the U.S. Department of Homeland Security was alerted to rule out any potential malicious attack, which officials confirmed within an hour was not a factor in the incident. Preliminary inspection results showed the odor was caused by a leak of non-toxic refrigerant from the facility’s aging heating, ventilation and air conditioning (HVAC) system, with no harmful contaminants detected in the air, and no controllers or support staff reporting serious health symptoms related to the exposure. The ground stop remained in effect for approximately 90 minutes while hazmat teams cleared the facility for reoccupation, after which the FAA gradually restored normal operations. As of Wednesday evening, the incident had caused more than 320 flight delays across the three major regional airports, 47 flight cancellations, and disruptions to travel plans for an estimated 41,000 passengers, with many transiting East Coast flights diverted to alternate airports in Philadelphia, Pittsburgh and Richmond. The FAA released a public statement late Wednesday noting it would conduct a full overhaul of the Potomac TRACON’s HVAC system in the coming weeks, and review its emergency contingency plans to minimize airspace disruptions in the event of future facility issues, given the critical role the hub plays in national airspace security and commercial travel.