The Full Aircraft Separation Transfer (FAST) study of the Freer-Flight Project looks at the “autonomous aircraft” mode in the context of free flight airspace by 2015. This can be allied to free route operations and support the introduction of designated Free Flight Airspace as proposed in the EUROCONTROL ATM2000+ Strategy. While these operations are likely to be confined to low traffic density airspace, they will further enhance flight efficiency and flexibility.New rules are needed to address the issues of communication, coordination, flight rules, separation principles and priorities among flights. For that purpose, Extended Flight Rules (EFR) procedures have been developed: encounters are treated pair-wise and a priority scheme determines which aircraft has the right of way. In addition, an Airborne Separation Assurance System (ASAS) prototype providing the pilot with the necessary assistance for conflict detection and resolution has been developed. The conflict detection provides a graphical representation of actual and potential zones of conflict, allowing straightforward conflict resolution through graphical trajectory editing. In addition, conflict resolution can be performed through system generated resolution trajectories. It is assumed that full intent information (Trajectory Change Points (TCP)) is transmitted between aircraft through Automatic Dependant Surveillance - Broadcast (ADS-B). Full Flight Management System (FMS) equipment is required.The experiment described in this paper aimed at gathering more data on autonomous operations from an aircraft perspective, specifically on the acceptability of the concept by pilots, through the evaluation of a prototype interface and of the corresponding procedures. A total of 18 pilots participated in the experiments run in a generic cockpit environment.Pilots were observed defining their own cockpit procedures to handle separation assurance in the absence of ATC, in particular to cope with non-nominal situations. They found the two levels of automation support for separation assurance very efficient and intuitive. Furthermore, they subjectively assessed that the additional workload induced by the separation task was very low, though some concerns were raised on the possible necessity of an ATC fallback in non-nominal cases.The zones on the display exclusively provided information on the interaction with other aircraft. The pilots expressed a need to integrate these zones on the same display with weather information, terrain and restricted airspace boundaries. A number of other enhancements to the tools were suggested by the pilots, warranting more experiments for a better understanding of the feasibility of autonomous operations.