Using ASDE-X Surveillance for Taxi-Out Time Benchmarking and Delay Estimation

Surface performance indicators for taxi-out delay depend on reference ideal unimpeded (nominal) times to identify areas in need of improvement. Current FAA practice derives unimpeded taxi-out times through a statistical analysis of ASPM-provided Out-Off-On-In (OOOI) sensor timestamps. This statistical technique uses a regression of taxi-times against the number of aircraft active on the surface to determine times of low congestion and presumably under conditions when times would be "unimpeded." These OOOI timestamps are rounded to the nearest minute and reported by a subset of carriers, leading to data concerns. Furthermore, the current unimpeded taxi-out method is only based on departure airport, operating carrier, season, and calendar year, which fails to include both start taxi-out location (gate/terminal) and wheels-off location (runway). Given these shortcomings, opportunities exist to estimate surface performance indicators through the use of surveillance data. Surveillance systems, such as the Airport Surface Detection Equipment-Model X (ASDE-X) system, provide aircraft temporal and spatial information by the second, enabling terminal area and runway information to be incorporated. The purpose of this paper is to utilize these new capabilities when identifying taxi-out routings that contribute the most to delay and inefficiency. The paper first assesses the current statistically derived unimpeded time against alternatives based on upper percentile benchmark methods. It then evaluates alternatives to current methodology by developing both an ASDE-X and hybrid ASDE-X/ASPM Key Surface Event Database. Techniques using the ASPM, ASDE-X, and hybrid surface databases are compared for five top U.S. airports during Fiscal Year 2014. Results show that ASDE-X provides better and more consistent data coverage when compared to the current ASPM process. An ASDE-X source also allows the taxi-start location to be identified, unlike ASPM. However, given existing data limitations, it is recommended that ASDE-X be supplemented with ASPM messages in order for an analysis to capture a more complete understanding of surface performance, specifically in the masked, non-movement area.