A passenger jet coming in to land at Heathrow Airport had a near miss with a UFO above Kent, newly-released British Ministry of Defence (MoD) files have revealed today.
The captain of the Alitalia airliner was so concerned he shouted "look out" to his co-pilot after seeing a brown missile-shaped object shoot past them overhead.
The mysterious incident near Lydd in 1991 was thoroughly investigated by the Civil Aviation Authority (CAA) and the military.
Having ruled out the object being a missile, weather balloon or space rocket, the MoD closed the inquiry and left the matter unsolved.
The unexplained close encounter is one of many recounted in military UFO documents made available online by the British National Archives.
Covering sightings from between 1986 and 1992, the 19 files include: a US Air Force pilot's account of being ordered to shoot down a UFO that appeared on his radar while he flew over East Anglia; an MoD request that Army and Navy helicopters should not take photographs of crop circles for fear of undermining the official line that the military did not investigate unexplained phenomena and a letter from a woman claiming to be from the Sirius system who said her spacecraft - also containing two "Spectrans" with "Mr Spock ears" - crashed in Britain during the Second World War.
However, one of the most intriguing episodes is the near-miss involving the Alitalia airliner at about 8pm on April 21, 1991.
The McDonnell Douglas MD80 aircraft was en route from Milan to Heathrow at 22,000ft with 57 people on board when pilot Achille Zaghetti saw the strange object some 1,000ft above him.
He recounted: "At once I said: 'Look out, look out', to my co-pilot, who looked out and saw what I had seen.
"As soon as the object crossed us I asked to the ACC (area control centre) operator if he saw something on his screen and he answered: 'I see an unknown target 10nm (nautical miles) behind you'."