A Trend Analysis of Air Traffic Occurrences in the UK Airspace

Abstract

The volume of air traffic has increased considerably in the United Kingdom in recent decades and with further predicted increases, there is concern that safety is not compromised. In the UK, the number of occurrences is a key safety performance indicator. An occurrence can be thought of as a failure in the chain of operations in the air traffic system. Some of these occurrences result in a loss of separation between aircraft, varying from a slight loss of separation posing no danger of collision to a very serious loss with a significant risk of collision, known as an airprox. However, in the UK this definition is extended to include controller overload that does not necessarily involve a loss of separation. This paper analyses recent occurrence trends in the UK airspace attributed to air traffic control during the period 1998 to 2000 using data from the Civil Aviation Authority and the United Kingdom Airprox Board. The results indicate a decline in the rate of occurrences over the period 1990–1999 due to safety aids on board aircraft and in control rooms. Furthermore, the different conditions under which airproxes occur have been explored and observations made on duration and causes of controller overloads.