On 8 August 2017, a Boeing 787-9 climbing through FL109 after departing Madrid received and promptly followed a TCAS RA ‘DESCEND' against crossing traffic at FL110 and this action quickly resolved the conflict. The Investigation found that both aircraft involved were following their IFR clearances and attributed the conflict to the controller involved who forgot to resolve a previously-identified potential conflict whilst resolving another potential conflict elsewhere in the sector. It was also found that the corresponding STCA activation had not been noticed and in any event had occurred too late to be of use.