On June 17, 1991, passengers aboard a Dan-Air Boeing 737 climbing out of Gatwick Airport reported seeing a dark, wingless object pass directly beneath their aircraft. The object came into view just minutes after takeoff as the plane ascended through approximately 14,000 feet on its scheduled flight to Hamburg. Eyewitnesses described the object as small, fast-moving, and unlike any conventional aircraft. Flight crew logged the sighting and informed air traffic control immediately. What followed was a chain of official confusion, contradiction, and quiet suppression that remains unresolved to this day.

Radar operators at Gatwick confirmed that an unidentified target had appeared on their screens at the same time and location described by the Dan-Air crew. The radar blip moved at an estimated 120 miles per hour and was tracked briefly before vanishing without explanation. No transponder code was associated with the object. No known aircraft had filed flight plans matching its path. In a controlled airspace zone that had recently seen an increase in flight traffic due to summer schedules, the presence of an uncooperative object at commercial altitude represented more than just an oddity. It was a serious breach of safety.

The Civil Aviation Authority (CAA) conducted a preliminary investigation and quickly issued a familiar explanation: the object, they claimed, was most likely a weather balloon. Balloons are frequently launched for meteorological purposes and occasionally drift into flight corridors. However, this particular conclusion was challenged almost immediately by the UK Met Office. Weather balloons released in the region that day had reached no higher than 6,000 feet. They were also bright orange or red in colour to enhance visibility. The object observed by the Dan-Air crew and confirmed on radar was dark, wingless, and traveling well above the known ceiling for such balloons.

Despite this contradiction, the case was closed internally with little fanfare. The CAA declined to pursue further analysis. The Ministry of Defence (MoD) did not open a formal inquiry. Files related to the incident remained classified until 2008, when a batch of previously restricted documents was released by the MoD as part of a nationwide declassification programme. Among the released records was the full incident report for the Dan-Air flight, including transcriptions of cockpit communications, radar logs, and Met Office objections to the balloon explanation.

The report describes the object as a projectile with no visible means of propulsion. Several passengers corroborated the flight crew’s account, describing a fleeting but unnerving moment where something dark passed beneath the left wing at high speed. One of the crew members noted that the object appeared to be under control rather than drifting. There were no contrails. No audible engines. No lights. Nothing to suggest it belonged to any known category of aircraft.

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Then, less than a month later, a Britannia Airways 737 flying a similar route near Gatwick experienced a near-identical encounter. In that case, the pilots reported a dark, lozenge-shaped object passing within 30 feet of their aircraft. Radar logs again showed an unregistered contact, moving at a comparable speed and altitude. The resemblance to the June 17 incident was striking, and internally, some officials noted the similarities. Yet again, the CAA defaulted to the balloon explanation, despite the Met Office repeating its concerns. In both cases, no physical evidence was recovered. No agencies took responsibility. No follow-up inquiries were made public.

The airspace around Gatwick has remained one of the busiest and most tightly monitored in the UK. An object flying at 14,000 feet in that region without identification, transponder signal, or clearance poses a risk that should have prompted more rigorous follow-up. But once the balloon theory was issued, institutional momentum allowed the matter to be shelved.