A TIME-BASED AIRBORNE INTER-ARRIVAL SPACING TOOL: FLIGHT EVALUATION RESULTS

An airborne tool has been developed that allows an aircraft to obtain a precise inter-arrival time-based spacing interval from the preceding aircraft. The Advanced Terminal Area Approach Spacing (ATAAS) tool uses Automatic Dependent Surveillance-Broadcast (ADS-B) data to compute speed commands for the ATAAS-equipped aircraft to obtain this interarrival spacing behind another aircraft. The tool was evaluated in an operational environment at the Chicago O’Hare International Airport and in the surrounding terminal area with three participating aircraft. Research pilots that were completely familiar with their aircraft were used for all test runs, minimizing the possibility of operational errors that might occur due to unfamiliarity. Two basic types of scenarios using different lateral navigation methods were flown: an area navigation (RNAV) path which transitioned onto the final approach course and vector scenarios in which headings were assigned to the first aircraft in the sequence. Data collected consisted primarily of aircraft state data, algorithm outputs, and pilot subjective comments. Both manual and autothrottle speed management were included in the scenarios to demonstrate the ability to use ATAAS with either method of speed management. The results on the overall delivery precision of the tool, based on a target spacing of 90 seconds, were a mean of 90.8 seconds with a standard deviation of 7.7 seconds. The results for the RNAV and vector cases were, respectively, M = 89.3, SD = 4.9 and M = 91.7, SD = 9.0. Pilots stated that the task of tracking the lateral path of the leading aircraft (vector scenarios), and following ATAAS-generated speed guidance was manageable and could be integrated into normal flying duties. Due to space limitations for this article, only limited detail of the ATAAS flight evaluation is possible; more details are provided in “Flight Evaluation and Demonstration of a Time-Based Airborne Inter-Arrival Spacing Tool” [Lohr, 2005].