September 19 is the anniversary of three UFO cases in three different decades. All of these encounters are significant in UFO history and are considered to also be among the best documented.

At 11:00am a silver disc-shaped object followed a Gloster Meteor returning to RAF Topcliffe, and seen by observers on the ground. It rotated whilst hovering. It then traveled towards the west at high speed. On 21 September, six RAF planes followed a spherical object over the North Sea. It followed one of the planes back to the base.

What follows is a collection of UFO reports were reported in the vicinity of the "Operation Mainbrace" NATO maneuvers that were held in September 1952. The maneuvers commenced September 13th and lasted twelve days. According to the U. S. Navy, "units of eight NATO governments and New Zealand participated, including 80,000 men, 1,000 planes, and 200 ships; in the vicinity of Denmark and Norway." The operation, directed by British Admiral Sir Patrick Brind, "was the largest NATO maneuver held up until that time."

September 13 - The Danish destroyer Willemoes, participating in the maneuvers, was north of Bornholm Island. During the night, Lieutenant Commander Schmidt Jensen and several members of the crew saw an unidentified object, triangular in shape, which moved at high speed toward the southeast. The object emitted a bluish glow. Commander Jensen estimated the speed at over 900 mph.

Within the next week, there were four important sightings by well-qualified observers. (Various sources differ by a day or two on the exact dates, but agree on details. There is no question about the authenticity of the sightings; the British cases were officially reported by the Air Ministry, the others are confirmed by reliable witnesses. All occurred on or about September 20).

September 19 - A British Meteor jet aircraft was returning to the airfield at Topcliffe, Yorkshire, England, just before 11 A. M. As it approached for landing, a silvery object was observed following it, swaying back and forth like a pendulum. Lieutenant John W. Kilburn and other observers on the ground said that when the Meteor began circling, the UFO stopped. It was disk-shaped, and rotated on its axis while hovering. The disk suddenly took off westward at high speed, changed course, and disappeared to the southeast.

September 20 - Personnel of the U.S.S. Franklin D. Roosevelt, an aircraft carrier participating in the Mainbrace maneuvers, observed a silvery, spherical object which was also photographed. (The pictures have never been made public). The UFO was seen moving across the sky behind the fleet. Reporter Wallace Litwin took a series of color photographs, which were examined by Navy Intelligence officers. The Air Force project chief, Captain Ruppelt stated: "[The pictures] turned out to be excellent...judging by the size of the object in each successive photo, one could see that is was moving rapidly." The possibility that a balloon had been launched from one of the ships was immediately checked out. No unit had launched a balloon. A poor print of one of the photographs appears in the Project Blue Book files, but with no analysis report.

At Karup Field, Denmark, three Danish Air Force officers sighted a UFO about 7:30 P.M. The object, a shiny disk with metallic appearance, passed overhead from the direction of the fleet and disappeared in clouds to the east.

September 21 - Six British pilots flying a formation of RAF jets above the North Sea observed a shiny sphere approaching from the direction of the fleet. The UFO eluded their pursuit and disappeared. When returning to base, one of the pilots looked back and saw the UFO following him. He turned to chase it, but the UFO also turned and sped away.

September 27/28 - Throughout Western Germany, Denmark, and southern Sweden, there were widespread UFO reports. A brightly luminous object with a comet like tail was visible for a long period of time moving irregularly near Hamburg and Kiel. On one occasion, three satellite objects were reported moving around a larger object. A cigar-shaped object moving silently eastward also was reported.

Betty and Barney Hill were an American married couple who rose to fame after they claimed to have been abducted by extraterrestrials on September 19­20, 1961. The couple's story, called the Hill Abduction, and occasionally the Zeta Reticuli Incident, was that they had been kidnapped for a short time by a UFO. Theirs was the first widely-publicized claim of alien abduction, adapted into the best-selling 1966 book The Interrupted Journey and a television movie.

The 1976 Tehran UFO Incident was a radar and visual sighting of an unidentified flying object (UFO) over Tehran, the capital of Iran, during the early morning hours of 19 September 1976. The incident is particularly notable for the electromagnetic interference effects observed upon aircraft coming within close proximity to the object: two F-4 Phantom II jet interceptors independently lost instrumentation and communications as they approached, only to have them restored upon withdrawal; one of the aircraft suffered temporary weapons systems failure, while preparing to open fire.

The incident, extensively recorded in a four-page U.S. Defense Intelligence Agency (DIA) report distributed to at least the White House, Secretary of State, Joint Chiefs of Staff, National Security Agency (NSA) and Central Intelligence Agency (CIA), remains one of the most well-documented military encounters with anomalous phenomena in history, and various senior Iranian military officers directly involved with the events have gone on public record stating their belief that the object was not of terrestrial origin.