A drone and passenger jet that came within 150ft (46m) of each other were at “serious risk of collision”, a report has said.
The captain of the EMB170 spotted the “dark” drone while 29 miles (46km) east of Southend on 24 March.
An Airprox Board report found the drone was flying above the permitted 400ft (122m) limit and was “endangering other aircraft” in the area.
The board concluded “providence” had played a major part in the incident.
The jet had just levelled off at about 9,000ft (2.7km) altitude, shortly after 18:00 GMT, when the flight officer saw the drone directly ahead of them, and it then flew above the plane, the report said.
The Airprox Board said: “The incident was best described as the drone was flown into conflict with the EMB170.”
It rated the incident risk in the highest category, A.