An unidentified drone came very close to colliding with a passenger jet in the summer, an official report to be published this week will say.
According to the Sunday Times (£), which has seen the Civil Aviation Authority's document on the risks associated with the growing popularity of drones, an Airbus A320 was involved in the incident at Heathrow airport on 22 July this year.
The pilot of the aircraft, which can carry up to 180 passengers on board, spotted the drone when the jet was travelling at an altitude of 700ft on its approach to the runway at the UK's busiest airport.
The CAA gave the dramatic event an "A" rating, which meant that there had been a "serious risk of collision" with the errant drone.
However, investigators were unable to detect the drone on air traffic control radar after the incident had occurred.
A spokesman at the CAA told the Beeb:
People using unmanned aircraft need to think, use common sense and take responsibility for them. There are rules which have the force of law and have to be followed.
In November, Met chief inspector Nick Aldworth warned a House of Lords sub-committee that "nefarious" private use of drones was on the rise in Blighty.
"We have undoubtedly seen this technology flown in controlled airspace, we have undoubtedly seen it used to harass people, and we have seen it flown in contravention of the air navigation orders, so I think that concern arises by the fact that there is clearly a means of offending that we do not seem to be able necessarily to address quickly," he said. ®