In a report by Airprox Board, the event was documented as a “high risk” incident, which resulted in safety procedures grounding planes at Heathrow.
On April 8 the pilot of an Airbus A320 reported a sighting of a drone at 11:35am 3000ft above Maidenhead.
Originally spotted on the right-hand side of the plane, Air Traffic Control asked the pilot if they were happy to continue their approach to the runway, to which the pilot approved as the drone was staying to the right of the centreline of their approach.
However, the drone later flew under the left wing, reportedly “only a few meters” from the engine.
Air Traffic Control was updated on the drone’s movements and made the decision to close the runway.
In the Airprox Board report, it added: “The pilot described the drone as being round shaped drone with purple/turquoise colour.”
The pilot later estimated that the drone came within three to 10 feet of the plane, with the risk of collision high and “immediate risk”.
As the controller considered this an immediate risk to the aircraft they immediately discontinued arrivals on RW09L and coordinated switching to RW09R.
The Heathrow Approach controller reported that the pilots of three different aircraft also spotted the drone in the vicinity.