A drone put 130 lives at risk when it passed directly over the wing of an aircraft approaching Gatwick Airport, a report has revealed.
A UK Airprox Board report said the drone was "flown into conflict" with the Airbus 319 on 9 July and said there was a high risk of a collision.
It said: "A larger aircraft might not have missed it and in the captain's opinion, it had put 130 lives at risk."
An "airprox" is when distances between aircraft are seen to compromise safety.
Former RAF and British Airways pilot Steve Landells said it was a "worrying near-miss that could have ended in tragedy".
The plane was preparing to land and a small, black object seen by the first officer was thought at first to be a bird before it became apparent it was a drone, the report said.
Twilight conditions at 20:35 BST meant the drone appeared black, or dark in colour, the report continued.
"At its closest point, it passed between the wing-tip and the fuselage, above the right wing," it said.
The plane landed safely and Gatwick police attended the incident at the West Sussex airport.
The report said the drone was "very large, certainly not a toy", with an estimated diameter of 1m (about 3ft) and four blades.
The report said the pilot's estimate of the distance, and his inability to avoid the object "portrayed a situation where providence had played a major part" in avoiding a collision.
In July, the Department for Transport (DFT) unveiled plans for a drone registration system after research found drones could smash plane windscreens.
Mr Landells, flight safety specialist at pilots' association Balpa, said the organisation wanted to see details of the legislation and a timescale for implementation.