NextGen Surface Trajectory-Based Operations (STBO): Evaluating Conformance to a Four-dimensional Trajectory (4DT)
A pilot-in-the-loop simulation was conducted to assess the feasibility of a Surface Trajectory-Based Operations (STBO) concept  . 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
... al 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, +/-30 sec (4DT 30 ) and +/-15 sec (4DT 15 ). 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 4DT 30 and 4DT 15 conditions afforded more than 99% conformance to the 4DT across the entire route. An evaluation of the time of arrival (TOA) at the endpoint revealed significantly less TOA error in the 4DT 30 and 4DT 15 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.