Quantitative Risk Evaluation of Obstacle Limitation Surfaces for Final Approaches at Airports

Obstacle limitation surfaces (OLS) are the main safeguard against objects that can pose a hazard to aircraft operations at and around airports. The standard dimensions of the most of those surfaces were estimated using the pilot’s experience at the time when they were included in the standard documents. As a result, some of these standards may have been overestimated, while others may not provide an adequate level of safety. With airports moving to the Safety Management System (SMS) approach to design and operations safety, proper evaluation of the level of safety provided by OLS at specific sites becomes important to airport operators. Therefore, this study attempts to collect actual flight path data using information provided by air traffic control radars and to construct a methodology to assess the probability of aircraft deviating from their approach path. This will be helpful to estimate safe and efficient standard dimensions of the OLS and assess the risk level of objects to the aircraft operations around airports. The methodology is presented using the aircraft trajectories of approaches at Ottawa International Airport (CYOW). Estimated dimensions of Code 3 approach surfaces also are presented.