NextGen Surface Trajectory-Based Operations (STBO): Evaluating Conformance to a Four-dimensional Trajectory (4DT)

Abstract

A pilot-in-the-loop simulation was conducted to assess the feasibility of a Surface Trajectory-Based Operations (STBO) concept [1]. The STBO concept was investigated from the pilot perspective by evaluating pilot conformance to a four-dimensional trajectory (4DT) while taxiing under manual control. Simulation conditions included a Current-Day Equipage condition; a verbal Speed-Advisory condition, which represented a near-term condition in which pilots were provided with verbal speed guidance from ATC, but not provided with any additional flight-deck tools by which to support schedule conformance; and two NextGen 4DT conditions in which the pilots were provided with flight deck displays to support conformance to the 4DT at two different levels, +/- 30sec (4DT30) and +/- 15sec (4DT15). In the NextGen 4DT conditions, pilots were presented with a graphical representation of the 4DT on an Airport Moving Map (AMM). Results showed that both the 4DT30 and 4DT15 conditions afforded more than 99% conformance to the 4DT across the entire route. An evaluation of the time of arrival (TOA) at the end-point revealed significantly less TOA error in the 4DT30 and 4DT15 conditions as compared to the Speed-Advisory condition. Although eye-tracking data revealed an increase in eyes-in time in the 4DT-display conditions, pilots rated this increase as acceptable. The results of this pilot-in-the-loop simulation demonstrated that the NextGen 4DT displays afforded high conformance with a substantial increase in predictability throughout the entire taxi route and at the runway queue. Pilots also rated that conforming to a speed profile, during taxi, was acceptable and safe.