On 6 July 2018, a Boeing 737-800 being positioned to join the intermediate approach sequence in the Barcelona CTR was obliged to take lateral avoiding action against an Airbus A320 ahead. The Investigation found that although both aircraft were in the same sector at the time, the controller had overlooked the presence of the A320 which had been transferred to the next sector before entering it prior to the controller involved routinely taking over the position. An on-screen alert to the developing conflict had not been seen by the controller. Minimum separation was 1.1nm laterally and 200 feet vertically.