The UK Airprox Board investigated a drone near-miss reported by a Boeing 747 near London Heathrow Airport on 23 June 2016. Separation distance reported as less than 200 feet.
The 747 pilot reported that he was inbound to Heathrow and positioning downwind at 4000ft when a drone passed over the nose of the aircraft, about 100ft above. No avoiding action was taken.
Reported separation: 100 ft (30 m) vertical / 0 ft (0 m) horizontal.
Aircraft: Boeing 747
Aircraft altitude: 4000 ft
Separation: 100 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.