An airliner carrying up to 186 passengers was forced to take avoiding action after a drone was spotted near Gatwick
The incident was revealed in a report by the UK Airprox Board (UKAB), who study near misses in UK air space.
It happened on 28th April and involved an Airbus A320, although the report doesn't name which airline was involved.
The aircraft was flying at 1,700ft when the pilot spotted the device.
The report explains how he was forced to turn right to dodge drone, missing by about 80-100ft.
This was classed as a Category A incident, the highest category risk.
Three other Category A incidents were discussed at the latest UKAB meeting.
The pilot of Boeing 747 was coming in to land at Heathrow Airport on June 6 when he saw a yellow and orange quadcopter pass down the left side of the plane.
In a separate incident, an Airbus A319 was at an altitude of 6,500ft approaching Gatwick.
The captain reported seeing a "metallic looking" drone that was "reflecting light".
The Civil Aviation Authority's code of conduct, known as the Dronecode, sets out rules for drone users.
These include staying below 400ft and flying at least 50m from buildings and people.
New legislation has also come into force banning the gadgets from being flown within 3.1 miles of airports.
Drone sightings at Gatwick Airport in December 2018 caused around 1,000 flights to be cancelled or diverted over 36 hours.
More than 140,000 passengers were affected in the run-up to Christmas.
Heathrow has also been forced to suspend flights this year because of drone activity.