The solution space for conflicts between aircraft consists of velocity, heading and altitude changes. In the current design of the air traffic controller workspace the instantaneous values for velocity, heading and altitude can all be found in the aircraft labels on the radar, however the heading and velocity can also be derived from the direction and speed of the aircraft on the radar display. Since the radar is a top view of the traffic situation, no means of deriving the altitude other than the aircraft labels can be found. Previous attempts to present the altitude domain in the radar display showed room for improvement. These display designs have been analysed and information gathered from them is used to create a new ecological user interface. The aim of this interface is to improve the support in conflict detection and resolution for air traffic controllers by representing the situation in the altitude domain. A preliminary feasibility test was performed from which it can be concluded that the altitude display has potential to improve safety in air traffic control and to reduce the complexity within the sector, but that some more attention should be put on making sure the aircraft leave the sector within the constraints linked to their exit waypoint. The subjective data from the questionnaire at the end of the feasibility test showed that the users felt that generally the display was easy to use.