FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-05/5

Title and Subtitle: The Air Traffic Control Operational Errors Severity Index: An Initial Evaluation

Report Date: April 2005

Authors: Bailey L, Schroeder D, Pounds J

Abstract: An initial evaluation of the Federal Aviation Administration�s (FAA) Air Traffic Control (ATC) Operational Error (OE) Severity Index (SI) was conducted by the Civil Aerospace Medical Institute�s (CAMI) Aerospace Human Factors Research Division (AAM-500). The SI is computed from data that, for the most part, can be objectively determined by post hoc investigation of OEs. Up to 100-points are assigned for varying levels of vertical separation, horizontal separation, closure rate, direction of flight paths, and the amount of controller awareness at the time of the OE. Based on the point totals, OEs are classified as: low (D), low moderate (C), high moderate (B), and high severity (A). This review and subsequent analyses focused on three key issues: (1) the distributional characteristics of operational errors, (2) the collision safety margin associated with SI point values, and (3) the objectivity associated with SI classifications of high moderate and high severity OEs.

We concluded that the SI provides a rational approach for categorizing the severity of ATC Operational Errors. Although questions remained as to the SI cut scores used to categorize OEs, it was recommended that the cut scores should not be changed unless objective measures can be developed to support those changes.

Key Words: Air Traffic Control, Operational Errors

No. of Pages: 16