The UK Airprox Board investigated a drone near-miss reported by Airbus A319 near London-Heathrow on 25 September 2015. Separation distance reported as 165-330 feet.
THE A319 PILOT reports approaching the LAM hold when ATC advised that a drone had been reported in the vicinity at FL080; consequently, both crew members were looking out for it. Upon leaving the hold, the FO spotted an object on the horizon, approaching them at the same level and in the opposite direction. As the object got closer it became obvious that it was either a drone or a balloon, it then passed between 50-100m off the right wing. As it passed, the FO was able to get a detailed look at it and could clearly see it to be a drone. It was a Quadcopter with two forward/downward looking lights on the central underside; it was of medium size, not a small toy drone. They immediately reported it to ATC with as much information as possible. The pilot noted his concern that a drone could be operating at such an altitude, in such a critically busy piece of airspace; he considered that it presented a serious risk of collision to their own aircraft and the other aircraft in the hold.
He perceived the severity of the incident 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 A319. Unsurprisingly, the incident did not show on the NATS radars and, therefore, the exact separation between the two air-systems was not known. However, the Board noted that the A319 pilot estimated the separation to be between 50m and 100m horizontally (more than a wingspan away); basing their assessment of risk on this estimate, it was therefore determined that the risk was Category B, safety margins had been much reduced below the normal.
Aircraft: Airbus A319
Aircraft altitude: 8000 ft
Separation: 165-330 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.