Collision avoidance systems in air and maritime traffic

In each transport mode, collisions between vehicles are one of the major operational risks. In maritime traffic collisions and groundings is the category with the highest frequency of all accidents. Although new navigational equipment, often combined with enhanced computer-based systems, is installed on ships' bridges, the number of collisions is still at a high level. The equivalent of ship collisions in air traffic is the mid-air collision. Compared to the maritime accident rate, mid-air collisions are very rare. In this paper we investigate the onboard collision avoidance process by focusing on technical support systems with implemented alerts to support the human operator. Empirical field studies have been undertaken to analyse the situation regarding the occurrence and handling of alerts onboard seagoing vessels. Especially with respect to collision avoidance alarms, the situation was found to be unsatisfactory. The algorithms in use are based on fixed static limit values and little selected information is used although new systems provide more and enhanced situation-specific data. A comparative study of the traffic-alert and collision avoidance system used by air traffic is made to identify potentials for synergies to improve maritime operational risk management. As an innovative approach, the development of a concept to adapt alarm thresholds automatically by using enhanced fast-time simulation techniques is introduced and discussed.