The afternoon of Sunday, June 25 turned chaotic for Washington D.C. area air traffic controllers when the TRACON facilities for airports in the area experienced an “equipment outage.” According to various sources, the staff of multiple air traffic control facilities were forced to evacuate their air traffic control buildings to allow maintenance crews to repair communications systems, leading to widespread delays. 

What is TRACON? 

Terminal Radar Approach Control Facilities, often shortened to "TRACON," refers to any large Federal Aviation Administration (FAA) air traffic control building that houses the radar air traffic controllers use to guide aircraft approaching and departing from airports. When a TRACON facility fails for whatever reason, be it due to a power or "equipment" outage, as air traffic control at Dulles International Airport (IAD) referred to the issue, it has a major effect. This especially becomes an issue when the airports involved in a TRACON outage are some of the busiest in the United States. TRACON does not include the ground control or "center" control facilities. Ground control facilities control aircraft operations on the ground of an airport, while "center" facilities are responsible for handling commercial jet traffic on 8 nautical mile wide "airways" (pre-cleared flight paths) above 18,000 feet. 

The Outage Begins:

It appears that the outage of Washington D.C. area TRACON facilities began around 17:00 local time, when according to flight tracking website Flightradar24, multiple flights began to experience delays. Shortly after this, many flights out of the three primary Washington D.C. area airports (Dulles, Reagan, and Baltimore Washington) began to be canceled. While many domestic (within the United States) flights were canceled, no international flights originating in the Washington D.C. area were canceled. However, most international flights were still delayed. 

Coincidentally during the outage, United flight 803 from Washington Dulles bound for Tokyo Haneda returned to its origin due to a mechanical issue, the airline confirmed. The Boeing 777-200ER was airborne for 1 hour and 30 minutes before it was forced to return, dumping approximately 5-6 hours of fuel in the process. 

At around 5:30 p.m. local time, TRACON facilities had their employees temporarily evacuated to allow workers to fix the communication systems at the Potomac Terminal Radar Approach Control facility. During this time, the facility was operating at an extremely limited capacity on a backup system, most likely a diesel generator or battery pack. 

During this developing situation, inbound traffic to the area diverted to airports in Pennsylvania (Pittsburgh, Philadelphia, Atlantic City, among others), while traffic meant to overfly Washington D.C. airspace was either placed in holding patterns outside the airspace or diverted around the problematic area. 

At approximately 6:00 p.m. local time, departures and arrivals into Dulles, Reagan, and Baltimore Washington airports began to be resumed, although with numerous delays and backups on the ground and in the air. Arriving flights into the area were sequenced to land as normal, while departing flights were sequenced to takeoff based on the amount of time each aircraft was delayed. 

According to air traffic control recordings at Dulles International Airport, traffic was departed from the airport with a spacing of 3 nautical miles (3.45 miles) between aircraft at five-minute intervals. These restrictions on departures were in place until 8 p.m. local time. 

Once most of the backlogged departures and arrivals had taken off and landed at their destinations, diverted flights originally bound for Washington D.C. airports began to arrive. One such example was Play Airlines flight OG 141, which was flying between Reykjavik and Washington Dulles when the flight was forced to divert to Pittsburgh during the TRACON outage. 

When Washington TRACON opened to arrivals again, the diverted Play Airlines flight took off from Pittsburgh and landed at Washington Dulles at around 8:15 p.m. local time, around 3 hours after the flight's scheduled arrival time. 

Washington D.C. Was Not the Only Area Delayed:

At the same time as the TRACON chaos was occurring in Washington D.C., other airports in the Northeastern United States came under delays and ground stops of various durations due to weather. Throughout the weekend of June 23-25, the Northeast area had been experiencing a wave of thunderstorms, with some of them becoming severe at times. On Sunday, June 25, temporary ground stops were issued at all three New York airports - John F. Kennedy, LaGuardia, and Newark - as well as numerous other important airports along the East Coast. Ground stops extended as far west as Detroit. 

If you are a passenger flying out of an airport experiencing operational difficulties or delays within the United States, you can check for updates via the official Twitter account of the FAA.