FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-03/8

Title and Subtitle: Development of an Empirically-Based Index of Aircraft Mix

Report Date: May 2003

Authors: Pfleiderer EM

Abstract: The present study is part of an ongoing effort to identify objective predictors of subjective air traffic controller workload. The study begins with a comparison of the salient variables governing en route controllers' perceptions of the performance capabilities of a sample of aircraft and the actual performance of the aircraft in the en route environment. A group of 24 Certified Professional Controllers (CPCs) from Kansas City (N = 17) and Boston (N = 7) en route centers provided estimates of cruising speed, climb, and descent rates for a sample of 24 aircraft types.

A matrix of squared Euclidean distances derived from summary measures (i.e., means of estimated speed, climb, and descent rates) was used to construct a classical multidimensional scaling (CMDS) model representing controllers' perceptions of the performance capabilities of each aircraft type. A second matrix was derived from means of speed, climb, and descent rates for the same 24 aircraft types computed from a sample of live air traffic data collected from the Kansas City and Boston en route centers. This matrix was used to construct a second CMDS model representing actual aircraft performance.

Interpretation of the dimensions of the CMDS model of ATC estimates suggested that Dimension 1 was related to engine type, whereas Dimension 2 was primarily associated with aircraft weight class. In the model of SAR data, both engine type and weight class were predominantly associated with Dimension 1. Results are used to develop a measure of aircraft mix (i.e., the mix of aircraft with different performance characteristics) to be added to a suite of controller activity and taskload measures.

Key Words: Aircraft Mix, Controller Workload, Sector Complexity, Traffic Complexity, Multidimensional Scaling

No. of Pages: 14