The UK Airprox Board investigated a drone near-miss reported by an Airbus A340-600 near Chigwell on 28 June 2016. Separation distance reported as 100-200 feet.
The pilot reported that he was in descent through FL090 when a drone was sighted just below and to the right of the nose of the aircraft. The drone was a multi-copter type and passed about 100- 200ft below his aircraft he estimated
Reported separation: 100-200 ft (30-61 m) vertical / 50 ft (15 m) horizontal.
Aircraft: Airbus A340-642
Operator: Virgin Atlantic
Aircraft altitude: 9000 ft
Separation: 100-200 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.