possibility of systematic discrimination against certain classes of aircraft operators (e.g., general aviation) when it comes to runway access. In a dynamic environment, this may even result in a compromise of safety, if some aircraft are indefinitely relegated to the end of the queue as new aircraft show up to land. These observations have led many investigators to study the runway-sequencing problem with the objective of increasing operating efficiency while ensuring that all airport users are treated equitably. Dear (1976) and Dear and Sherif (1991) developed the concept of constrained position shifting (CPS), i.e., of a limit in the number of positions by which an aircraft can deviate from its FCFSposition in a queue. For instance, an aircraft in the 16th position in a FCFS queue would have to land in one of the positions 14–18 if the specified maximum position shift (MPS) is 2. Through many numerical examples and for several reasonable objective functions, Dear (1976) showed that by setting MPSto a small number, such as two or three, one can obtain most of the benefits of an unconstrained optimized system (e.g., 60%–80% of the potential improvements). This finding motivated several researchers (e.g., Psaraftis 1980, Venkatakrishnan et al. 1992, Bianco et al. 2001) to investigate a number of increasingly complex and realistic versions of the sequencing problem. Two advanced terminal airspace automation systems, CTASand COMPAS, that have been implemented in the United States and in Germany, respectively, incorporate sequencing algorithms based on CPS(Erzberger 1995). However, this feature of CTASand of COMPAShas not been activated, primarily because of concerns about a potential increase in controller workload