1. Identification And Significance Of The Problem

The objective of this research is to design and demonstrate an agent-based modeling and analysis tool for evaluating General Aviation (GA) pilot situation awareness under free flight air traffic management (ATM). A computational tool is developed to assess free flight’s potential effect on GA operators, by combining an agent-based representation of the overall pilot/vehicle/ATM system with quantitative modelbased metrics of pilot SA. The model’s performance is demonstrated in a set of simulation trials designed to measure the pilot agent’s ability to recognize and correctly assess protected zone conflicts in free flight ATM, using information available from a hypothetical cockpit display of traffic information. A set of simulations is presented to examine the effect of sensor accuracy and attention allocation on pilot awareness of protected zone conflict hazards posed by intruder aircraft. The results show that reducing sensor accuracy leads to an increase in overall SA error, and that the pilot agent divides its attention over multiple traffic hazards in proportion to each intruder's hazard potential. This attention-sharing varies dynamically as the conflict situation changes, in a manner that is consistent with intuitive expectations. INTRODUCTION Nascent concepts for free flight air traffic management (ATM) will dramatically change human roles and tasks in the airspace system. Free flight, which has been defined as “a safe and efficient flight operating capability under instrument flight rules (IFR) in which operators have the freedom to select their path and speed in real time” [1], will have profound implications on pilot information requirements, pilot/controller roles * Research Engineer. Member AIAA. † Senior Scientist. Senior Member, AIAA. ‡ Principal Scientist. Member, AIAA. § Assistant Professor. Member, AIAA. Copyright © 1998 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. and responsibilities, workload allocation, communication, and decision-making. Such systemic changes will inevitably introduce new human factors challenges and new sources of human error. It has often been the case that human factors issues are normally only addressed very late in development, often too late to facilitate necessary changes [2]. If it is accepted as fact that aviation safety not be compromised in a transition to free flight, human factors issues should be addressed concurrently with the development of free flight technologies and procedures. Although continuing advances in on-board automation and aiding systems should ameliorate safety concerns in the commercial cockpit, there is considerable concern regarding the impact of free flight on the general aviation (GA) community. This community represents approximately 95% of all aircraft and 60% of aircraft operations hours in the continental United States. Thus far, the consequences of free flight on GA have received relatively little attention. The safety of GA operations under free flight will hinge on the adequacy of the equipment needed for free flight and the operating procedures that support it [3]. Of specific importance are the requirements for supporting adequate pilot situation awareness (SA). Situation awareness, which refers to a pilot’s internal model of the world around him at any point in time [4], is the starting point for pilot decision-making, particularly in abnormal or emergency situations [5]). The pilot obtains information to maintain awareness of the flight situation visually (through aircraft windows and from instruments), aurally (from other crewmembers and over radio communications), and through vestibular senses. The information thus obtained forms the basis of the pilot’s decisions. Since all of the pilot’s information-gathering skills are subject to error, failures in maintaining adequate SA can severely impact flight safety. For example, a recent study of fatal commercial aircraft accidents involving controlled flight into terrain (CFIT) implicates loss of SA as a dominant factor [6].