A passenger jet coming in to land at Heathrow Airport had a near miss with a UFO, according to newly-released British Ministry of Defense files.
The captain of the Alitalia airliner was so concerned he shouted "look out" to his co-pilot after seeing the brown missile-shaped object shoot past them overhead.
The mysterious incident near Lydd in Kent in 1991 was thoroughly investigated by Britain's Civil Aviation Authority (CAA) and the British military.
But 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 now made available online by the National Archives.
Documents show the McDonnell Douglas MD80 aircraft was en route from Milan to Heathrow at 22,000 feet with 57 people on board when pilot Achille Zaghetti saw the strange object 1,000 feet 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 center) operator if he saw something on his screen and he answered 'I see an unknown target 10 nm (nautical miles) behind you'."