On 25 July 2016, an Airbus A320 and an Airbus A321 both departing Barcelona and following their ATC instructions came into conflict and the collision risk was removed by the TCAS RA CLIMB response of the A320. Minimum separation was 1.2 nm laterally and 200 feet vertically with visual acquisition of the other traffic by both aircraft. The Investigation found that the controller involved had become preoccupied with an inbound traffic de-confliction task elsewhere in their sector and, after overlooking the likely effect of the different rates of climb of the aircraft, had not regarded monitoring their separation as necessary.