We conducted an 18 month study on the implementation and evaluation of a portable eye tracking system in a training environment. The system was used by F-16 simulator instructors to provide instructional feedback to F-16 student pilots during flight simulator training missions. The head-mounted components of the eye tracking system consist of a two-dimensional eye position measurement system and a miniature video scene camera. When displayed on a video monitor, a cursor corresponding to the student's line of sight allows the instructor to follow the student's visual scan pattern. The portable system can be used in a number of environments and applications to objectively assess visual behavior, to develop effective visual behavior, and to enhance training. In addition, the companion, real-time, automated analysis system can analyze, quantify, and summarize scan path behavior from recorded videotape.