It was certainly a close encounter, but with precisely what remains a mystery.
An airline pilot has reported a near miss with a "rugby ball-shaped" UFO that passed within metres of his passenger jet near Heathrow airport.
He told aviation authorities investigating the incident last July that he was certain the object was going to crash into his aircraft and that he ducked as it headed towards him.
They have been unable to establish the identity of the mysterious craft, which apparently approached the airliner at great speed.
The incident occurred while the Airbus A320 was cruising at 34,000ft, around 32 kilometres west of the airport.
The investigators' report states: "He was under the apprehension that they were on collision course with no time to react. His immediate reaction was to duck to the right and reach over to alert the FO [First Officer]; there was no time to talk to alert him."
It adds: "The captain was fully expecting to experience some kind of impact with a conflicting aircraft."
He told investigators the object passed "within a few feet" of the top of the jet and that it was "cigar/rugby ball-like" in shape, bright silver and "metallic" in construction. The episode was examined by the UK Airprox Board, which studies "near misses" involving aircraft in British airspace.
It checked data recordings to establish what aircraft were in the area but eliminated them all, along with meteorological balloons. Military radar operators were also unable to trace the reported object.
The sighting occurred in daylight, at around 6.35pm on July 13. It has emerged following the publication of the report, which concluded it was "not possible to trace the object or determine the likely cause of the sighting".
The document does not name the airline or flight involved in the incident. Even though it describes the aircraft as being "just to the west of Heathrow", aviation experts believe that at such an altitude it would be unlikely to have taken off from, or be preparing to land at, the west London airport.
Instead, the A320, which is popular with many carriers, among them British Airways and Virgin, is likely to have been travelling between a regional airport elsewhere in the UK, and another on the Continent. The aircraft typically carry about 150 passengers.
The British Ministry of Defence closed its UFO desk in December 2009, along with its hotline for reporting such sightings. Following that change, the Civil Aviation Authority took the decision that it would continue to look into such reports, from aircrew and air traffic controllers, because they could have implications for “flight safety”.
In 2012, the head of the National Air Traffic Control Services admitted staff detected around one unexplained flying object every month.
Dr David Clarke, a Sheffield Hallam academic and the UFO consultant for the National Archives, said: “The aviation authorities obviously think this is something they should continue to look into and if you are a regular air traveller, you are likely to agree.”
Dr Clarke, a sceptic on UFO issues, said: “This latest sighting is interesting, because it is detailed and clear. These pilots don't file these reports for something and nothing. There was obviously something there.”
Chris Yates, an aviation consultant, said: “Although we assume when these things happen, a UFO is responsible, there is usually an explanation that materialises at some point.”
The Telegraph, London