Changes in Air Traffic Management, exemplified by the NextGen and SESAR projects, intend to achieve ATM systems with a higher capacity and also higher efficiency, through more direct routing. At the same time, air traffic safety should continue to increase. An important step in this process can be the partial or full transfer of responsibility for separation to the flight deck, using Airborne Separation Assurance Systems (ASAS). This paper discusses the development of interfaces for ASAS operations using Ecological Interface Design. Rather than focusing on the development and testing of the displays themselves, it addresses the parallels and differences between EID in the process control domain (from which EID originated) and EID in the air traffic domain.