From the Associated Press:
Alitalia pilot Achille Zaghetti thought it was a missile.
Zaghetti was at the helm of a jet from Milan to London's Heathrow Airport on the evening of April 21, 1991 when a flying object streaked across his field of vision.
"At once I said, 'look out, look out,' to my co-pilot, who looked out and saw what I had seen," Zaghetti wrote in his report. "As soon as the object crossed us I asked to the ACC (area control center) operator if he saw something on his screen and he answered 'I see an unknown target 10 nautical miles behind you."'
An investigation later ruled out a missile - but never ruled anything in, either.
The close encounter is one of many reported UFO sightings among 19 files that Britain's National Archives posted Monday to the Web. The new material covers UFO sightings between 1986 and 1992.
While the 1,500-page batch of documents debunks a host of UFO sightings, others like Zaghetti's near-miss with a UFO remain unexplained.
UFO sightings, 1986 - 1992
These files contain reported sightings of Unidentified Flying Objects (UFOs) between 1986 and 1992. Highlights include the near collision of a passenger jet and UFO in Kent and the pilots of a US Air Force jet being ordered to shoot down a UFO over East Anglia.
This is the second batch of UFO files released to the National Archives by the Ministry of Defence - the first instalment was released in May 2008. They contain a wealth of information for anyone interested in the subject. UFO expert Dr David Clarke also provides a videocast guide to the information contained in the files.
Go to the UFO files page to view files and supplementary information.