A runway veer-off risk assessment based on frequency model: Part II. risk analysis

This two-part paper presents a comprehensive airport risk assessment methodology for aircraft runway veer-off accidents around the world. Veer-off is a lateral runway excursion, and it occurs when an aircraft gets out the runway during a movement. The most frequent causes for this type of accidents are inappropriate pilot performance and aircraft condition; while influential factors include transversal wind, contamination of the runway, and poor visibility. The consequences of these events involve both damage to the aircrafts and potential health effects on passengers and crew members. Statistical data collected by the authors were used as reference for conducting frequency and risk assessments of veer-offs. A successful probabilistic model of veer-off accidents was developed in the first part of the paper. This second part assesses the level of safety guaranteed by the Cleared and Graded Area (CGA), which is a part of the runway strip that enhances the deceleration of an aircraft in case of an excursion. This area has to be dimensioned according to the requirements provided by the International Civil Aviation Organization Standards (ICAO) and the regulations issued by the Italian Civil Aviation Authority. Therefore, a model of veer-off accidents was developed to quantify the risk of an event. The results from the risk analysis showed that there are some cases for which the Real Level of Safety (RLS) was higher than the proposed Target Level of Safety (TLS), meaning that the level of damage expected is higher than the proposed one. An application example of the model complying with the requirements of the ICAO Regulation for non-instrument Code A runways is also presented. Overall, the results obtained from this study show the proposed model contributes to the implementation of Safety Management Systems at airports, as stipulated by the ICAO.