The 1952 Washington, D.C. UFO incident, also known as the Washington flap, the Washington National Airport Sightings, or the Invasion of Washington, was a series of unidentified flying object reports from July 12 to July 29, 1952, over Washington, D.C. The most publicized sightings took place on consecutive weekends, July 19–20 and July 26–27. UFO historian Curtis Peebles called the incident "the climax of the 1952 (UFO) flap" - "Never before or after did Project Blue Book and the Air Force undergo such a tidal wave of (UFO) reports."
At 11:40 p.m. on Saturday, July 19, 1952, Edward Nugent, an air traffic controller at Washington National Airport (today Ronald Reagan Washington National Airport), spotted seven objects on his radar. The objects were located 15 miles (24 km) south-southwest of the city; no known aircraft were in the area and the objects were not following any established flight paths. Nugent's superior, Harry Barnes, a senior air-traffic controller at the airport, watched the objects on Nugent's radarscope. He later wrote:
Barnes had two controllers check Nugent's radar; they found that it was working normally. Barnes then called National Airport's radar-equipped control tower; the controllers there, Howard Cocklin and Joe Zacko, said that they also had unidentified blips on their radar screen, and that they had seen "a bright light hovering in the sky...[it] took off, zooming away at incredible speed." Cocklin told Zacko "Did you see that? What the hell was that?"
At this point, other objects appeared in all sectors of the radarscope; when they moved over the White House and the United States Capitol, Barnes called Andrews Air Force Base, located 10 miles from National Airport. Although Andrews reported that they had no unusual objects on their radar, an airman soon called the base's control tower to report the sighting of a strange object. Airman William Brady, who was in the tower, then saw an "object which appeared to be like an orange ball of fire, trailing a tail . . . [it was] unlike anything I had ever seen before." As Brady tried to alert the other personnel in the tower, the strange object "took off at an unbelievable speed." On one of National Airport's runways, S.C. Pierman, a Capital Airlines pilot, was waiting in the cockpit of his DC-4 for permission to take off. After spotting what he believed to be a meteor, he was told that the control tower's radar had detected unknown objects closing in on his position. Pierman observed six objects — "white, tailless, fast-moving lights" — over a 14-minute period. Pierman was in radio contact with Barnes during his sighting, and Barnes later related that "each sighting coincided with a pip we could see near his plane. When he reported that the light streaked off at a high speed, it disappeared on our scope."