The UK Airprox Board investigated a drone near-miss reported by Boeing 777 near London-Heathrow on 22 September 2015. Separation distance reported as 80 feet.
THE B777 PILOT reports being in the climb-out from Heathrow when, on passing 2000ft, the Captain saw a silver or metallic drone pass down the right-hand-side of the aircraft at the same height. He described the drone as a Quadcopter type, silver or metallic in colour with “coke can” size cylinders at each corner. He estimated it to be 12-18 inches diameter. The aircraft was climbing, and therefore had a nose up attitude, which meant that the crew had limit forward visibility; the encounter was only fleeting as the drone passed down the right-hand-side, lasting probably 1-2 seconds. There was no time to take avoiding action.
He assessed the risk of collision as ‘High’.
Operating as he was in airspace within which he was not permitted meant that the Board considered that the cause of the Airprox was that the drone operator had flown into conflict with the B777. As is often the case with drone Airprox, the incident did not show on the NATS radars; the B777 pilot estimated that the drone was at the same height and within 25m of the B777, less than a wingspan away. Using this estimate as a guide, the Board determined that the risk was Category A, separation had been reduced to the minimum and chance had played a major part in events.
Aircraft: Boeing 777
Aircraft altitude: 2000 ft
Separation: 80 feet
Please note that separation distances are solely based on pilot’s judgements and not necessarily accurate since horizontal and vertical separation distances can be hard to judge.