Aircraft self-separation is a concept in which the responsibility for aircraft separation is shifted from the ground to the air. To make self-separation possible the aircraft is equipped with an Airborne Separation Assurance System (ASAS). It is thought that with ASAS both capacity and safety will be improved. This article reviews an experiment in which the concept was tested using 24 pilots at the same time, flying together using PC-based simulators in a computer network. Results showed that separation can be maintained, even in extreme situations. Results also demonstrated that the pilot models used in computer simulation show behavior very similar to that of pilots in cockpit simulators. Finally, results also showed that in this simulation, pilot workload due to the extra task of maintaining separation is low. Competitive "gaming" among aircraft was not evident.