Runway veer-off accidents: Quantitative risk assessment and risk reduction measures

The attention to airport safety-related issues has grown fast in recent decades. The experience gained in these themes reveals the importance of assessing and mitigating the accident risk in the airport context. This work presents a quantitative risk assessment method useful to calculate the current level of risk for different runway codes and types of movement. The model consists of cumulative probability distributions, which describe the final position of an aircraft after a veer-off, and a damage model, which considers statistical mechanical damages and injuries observed in the examined database. The current levels of veer off risk range between the orders of magnitude 10−8 and 10−10, varying for runway code and type of movement. Geotechnical and geometrical characteristics of the Cleared and Graded Area (CGA) width play a fundamental role in reducing veer-off risk. An enlargement of CGA could be an effective strategy, as demonstrated by the carried-out sensitivity analysis: the obtained results demonstrate important reduction (up to 63%) of the risk of the main landing gear departing beyond the CGA (RCGA_GEAR). For instrument runways, the average reduction of RCGA_GEAR is sensitive, even when the CGA enlargement is only 5 m-wide (i.e. 10% for landing and 7% for take-off). The strategy proposed by the authors does not require modification of airplane technologies and safety devices for passengers, moreover it complies with the ICAO investigation for mitigating consequence of this type of accidents. Therefore, the results of the study could have a significant impact on the risk management in airport.