Pilots spotted a gadget with multiple arms and up to eight rotors pass by the right hand side of the plane as it was preparing to land.
Both pilots exclaimed: "Was that a drone? At 10,000 feet!", air safety experts UK Airprox Board (UKAB) said.
The drone was estimated to be about 98ft (30m) away from the plane and "safety was not assured", UKAB added.
Large drones are not permitted to fly above 400ft (121m) or within proximity of airports or airfields.
It happened on 11 November 2016, so quickly the Airbus A320 pilots said they had "no time to react".
