UK Airprox board has reported pilots on an Airbus A320 aircraft descending on its base leg over central London in preparation for its approach to Heathrow sighted a black drone, the board said.
Investigators disclosed details of three additional encounters, within three days, between commercial aircraft and unmanned aerial vehicles in London terminal airspace, including two in the highest collision risk category.
Investigators state that the incident appeared to be a very near miss, adding that the vehicle´s operator could not be traced.
The event occurred two days after another encounter involving an A320-family jet on descent on the same Heathrow runway. Its crew had been advised of a possible drone sighting by a preceding aircraft, and had increased their vigilance, when they saw a quadrotor vehicle pass overhead.
In its review, Airprox says the pilot noted the encounter took place during a period of high workload as the aircraft executed a continuous-descent approach. The operator of the vehicle could not be located.
Both events were assessed by the organisation as bearing a high risk of collision. The Airprox board has also noted a third incident, which occurred on 17 July, during which an A319 passed a drone at a height of 1,000 feet on approach to Heathrow.