Airport capacity is becoming a bottle neck to the increasing air traffic demand. It is highly desirable to develop computer automation systems that enable maximum throughput and capacity in the airport environment. In particular, plans for the Next Generation Air Transportation System (NextGen) 1 call for the transition of airport surface movements from today’s relatively ad hoc nature to trajectory-based operations. 2–7 An essential component of trajectory-based surface operations is the efficient and reliable planning and prediction of aircraft surface trajectories.

Surface trajectory prediction estimates the most likely future trajectories for individual aircraft, based on surveillance data and the assumed or assigned intents of the pilot-aircraft systems. It provides estimates of times of arrival (TOA) and other useful state information at various checkpoints along assigned routes. Such a capability, if sufficiently accurate over a reasonable time horizon, can be utilized by decision support tools to provide enhanced situational awareness and to improve decision making. It is a key enabler for advanced scheduling, conformance monitoring, and conflict detection and resolution capabilities envisioned in the transformation to trajectory-based operations under NextGen. In contrast, trajectory planning seeks to generate the most desirable trajectory for an aircraft under various performance and operational constraints. The output of this process is the assigned trajectory delivered to the pilot-aircraft system. For both trajectory planning and prediction, proper trajectory models are necessary that can accurately describe the responses of individual aircraft to controller commands and external conditions. This paper systematically examines and evaluates different choices of trajectory models for aircraft surface movements. The need for proper surface trajectory models has been recognized by the air traffic research community. The Surface Management System (SMS) 8 is a decision support tool for airport surface scheduling and management that has been successfully used to improve the efficiency of surface operations. 9 SMS utilizes a surface trajectory model based on constant speed and instantaneous acceleration to predict taxi times to a specific airport resource such as a departure runway. 10 Controllers would use these predictions in managing demand for airport resources. 11, 12 More advanced surface research concepts, such as taxi scheduling optimization, use constant speed trajectory models to establish the initial schedule and sequence of aircraft at a runway, as well as at a number of taxiway intersections along the route. 4, 13 However, the assumption of constant speed and instantaneous acceleration may not always be realistic. 14, 15 Because of the importance of surface trajectory models to the accuracy and efficiency of advanced surface management decision tools, it is imperative to develop more realistic surface trajectory models.