The captain of the packed Airbus A320 spotted the silver object heading straight for the cockpit as his plane flew above Berkshire.
He was looking out of the left window a split second before the bizarre incident.
A safety report said: “As he turned to look ahead, he perceived an object travelling towards them at what appeared to be the same level, slightly above the flight deck windscreen.
“Having very little time to focus, he was under the apprehension that they were on a collision course with no time to react.
Full account here