Aeronautical surveillance manual Air traffic is growing at a significant rate and at the same time there are increasing demands for more operating flexibility to improve aircraft efficiency and to reduce the impact of air travel on the environment. This document addresses aeronautical surveillance systems as major elements of modern air navigation infrastructure required to safely manage increasing levels and complexity of air traffic. It provides a. basic understanding of various systems and how they are used for air traffic surveillance while the appendices contain detailed information on some specific systems and related topics.