A METHOD FOR RATING THE SEVERITY OF RUNWAY INCURSIONS Kim Cardosi, Cardosi@volpe.dot.gov Daniel Hannon, Thomas Sheridan, U.S. Department of Transportation, Volpe Center, 55 Broadway, Cambridge, MA William Davis, U.S. Department of Transportation, Federal Aviation Administration, Office of Runway Safety and Operational Services, Suite 7225, 490 L’Enfant Plaza, Washington, DC Abstract Risk is a function of the probability of an event and the severity of the consequences of that event. Any discussion of issues of risk in surface operations must include a valid and reliable measure of the severity of the outcome of runway incursions. This paper describes an automated method for rating the severity of the outcome of runway incursions. This model was developed using the same criteria and decisions that experts currently use to determine the severity of an incursion. The model assigns a severity rating based on the information contained in the preliminary report of the incident. This includes: the geometry of the situation that resulted in the incursion and the closest proximity (horizontal or vertical), visibility, type aircraft, and whether or not (and characteristics of) the avoidance maneuver. The initial validation was conducted by comparing the model’s assessment of 307 runway incursions to the assessment conducted by a panel of subject matter experts in the FAA Runway Safety Office. In 92% of the incidents, the model matched the group’s ratings (of three levels of severity). Patterns of discrepancies are well defined and discussed. Ongoing validation efforts are also described. Finally, possible applications to losses of standard separation in the air are explored. Introduction At the Eleventh Air Navigation Conference in Montreal (September 2003) the International Civil Aviation Organization (ICAO) was challenged to “urgently progress the development of a formal definition for ‘runway incursion’ as a prerequisite for further actions to be taken in this domain.” Also expressed was a need to develop a standardized runway incursion severity categorization taxonomy. Information on runway incursions is not readily comparable across countries, in part, due to the differences in the definition of runway incursion. The United States’ Federal Aviation Administration (FAA) has defined a runway incursion as: “Any occurrence in the airport runway environment [with an operating control tower] involving an aircraft, vehicle, person, or object on the ground that creates a collision hazard or results in a loss of separation with an aircraft taking off, intending to take off, landing, or intending to land.” [1]. The definition of a runway incursion that was adopted by ICAO as of 25 November 2004 (and that will be used by the United States in the future) is “Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and takeoff of the aircraft.” An international standard for the definition of a runway incursion is the foundation for being able to share data across aviation authorities. Another critical step toward being able to analyze runway incursion data, either within a state or across states, is a standardized method for categorizing the severity of runway incursions. The validity of any analysis that speaks to (such as the causes of) “serious incidents” compared to less serious incidents is routed in a reliable and valid method of determining the severity of such incidents. Such a method for determining severity is also necessary for risk assessments (of procedures, equipment, etc). Since “risk” is a function of the probability of an event and the severity of the consequences of the event, a valid and reliable measure of the severity of the outcome of a runway incursion is essential for measuring the risk of surface operations. 1