The Britannia Airways Black Lozenge near Gatwick

In 1991, the skies over southern England were busy, and strange. In April, an Alitalia crew reported a missile-like object over Lydd, Kent. On 17 June, passengers on a Dan Air 737 climbing out of Gatwick for Hamburg saw "a wingless projectile pass below and to the left." About a month later, it happened again.

15 July 1991. A Britannia Airways Boeing 737 was on its way home from Greece, from Crete according to the press. It was descending towards Gatwick at 14,000 feet.

The crew saw "a small, black lozenge-shaped object" zoom past at high speed, 100 yards off the port side. The co-pilot later spoke of a "black lozenge-like object." Newspaper accounts in 1992 put it far closer. They said it took "less than two seconds to pass just 30 feet above the airliner's wing." The two distances have never been reconciled.

Gatwick controllers confirmed that "a 'primary contact' was visible on radar 10 nautical miles behind the 737 moving at a speed estimated as 120 mph." A primary contact is a raw echo. No transponder answered.

Then the object seemed to turn. Controllers warned the captain of another aircraft, which made "avoiding turns to the left to avoid the [UFO], which had appeared to change heading towards it." By then the object had disappeared from view.

The case went to the UK Airprox Board. Its working group finished its report in April 1992. It could not explain the incident. The object "might have been an escaped balloon," the group thought, but it was "unsure what damage could have occurred had the object struck the 737; the general opinion was that there had been a possible risk of collision."

The press picked up the story on 28 and 29 April 1992. The Liverpool Daily Post ran it under the headline "UFO Near Miss Scare Baffles the Scientists," reporting that Jodrell Bank Observatory and NASA were stumped.

The Civil Aviation Authority suggested a small test balloon or a weather balloon. A weather balloon released in the area the same day drew most of the speculation. The Met Office pushed back: "A cloud-based balloon would only reach 6,000 feet. It would never reach the height of the plane. It would be an orange/red color, not black." That objection covers a cloud-base balloon, though, not the larger escaped balloon the board had in mind. No investigation ever determined what the object was.

In October 2008, the Ministry of Defence UFO files covering 1986 to 1992 were released through The National Archives. The black lozenge was back in the news. Researcher David Clarke later placed it in a long history of mystery objects in Gatwick airspace, a history that runs all the way to the drone incident of December 2018. Clarke's sources tell the same story the board did. Something small, black and fast passed an airliner at 14,000 feet. Nobody could say what it was.