Review: Analysis and Improvement of Traffic Alert and Collision Avoidance System

Several well-known international cooperation programs in the research field of air traffic management, e.g., SESAR and NextGen, aim to overcome the deficiencies of airspace capacity, while ensuring safety level and efficient operations. The increasing airspace traffic density would cause congested traffic scenarios, which require the developed safety procedures to resolve multithreat conflicts. In this paper, we provide a complete survey on the conflict detection and resolution approaches (CDR), mainly including long term CDR, medium term CDR, and short term CDR on three different levels classified based on the acting period. In order to achieve absolute security, it is very important to conduct a summarization of previous and present study on the traffic alert and collision avoidance system (TCAS), utilized as the final means in the security technology system. This review not only offers an intuitionistic and in-depth comprehension of the potential collision emergence for risk assessment, but also summarizes the various encounter models for the TCAS analysis and different strategies for the TCAS improvement, making an overall perspective of the research progresses and trends to facilitate the development.