An Air France Airbus A320 narrowly avoided colliding with a drone while descending for an approach to Paris Charles de Gaulle airport last month, the French aviation investigation agency BEA said.
The aircraft had been operating a service from Barcelona on February 19 and was flying at 5,500ft when the co-pilot saw the drone.
He immediately disengaged the autopilot and carried out an avoidance manoeuvre while informing the captain of the drone's presence, BEA said on its website.
The drone passed just five metres below the aircraft's left wing, the agency said, classifying the incident as "serious".
An investigation is ongoing.