Mental imagery plays a role in air traffic control that is mostly overlooked. Air traffic controllers may use imagery for various purposes, such as to aid judgement, to establish situation awareness, and to support perception, memory, and learning. Indeed, controllers colloquially report the importance of their 'mental picture' as fundamental to controlling. This paper briefly explores mental imagery in air traffic control, and reviews some of the theoretical literature on mental imagery, introducing some issues and questions of relevance to ATC.