Improvements of a previously developed tunnel display for curved trajectory following have been experimentally evaluated. A fixed-base simulator study has been carried out, in which eight pilot subjects flew a simplified linearized trim model of a large transport aircraft along eight different curved and descending approach trajectories under various experimental conditions. The purpose of this study was to evaluate an new predictor guidance scheme based on an actively driven predictor reference window, The results showed that, for the larger prediction times, the new guidance scheme yielded a superior performance as compared to the original configuration, in which a nonactive predictor reference window was used. Corner cutting, as experienced in earlier configurations, was eliminated, resulting in a highly improved positional accuracy in transitions from straight to curved trajectory sections and back. Furthermore, cross track errors, resulting from low-frequency disturbances, such as slow-varying crosswinds, were greatly reduced as a result of the integral control action imparted to the predictor reference window without affecting the task difficulty. Subject response has been found to strongly resemble the one of a well-designed autopilot.
