Safety Control Management at Airport Taxiing to Take-Off Procedure

Abstract

Air traffic control (ATC) system is a safety critical system because its failure may result into loss of life, considerable financial and environmental damages. Modelling safe and efficient ATC system is an open research problem and has become a challenging task due to its complexity and ever increasing traffic at airports. It is reported in the literature that a number of collisions occurred at airports surface are three time larger than the collisions in the airspace. The delays at airport surface require effective safety and guidance protocols to control traffic at the airport. In this paper, formal procedure of managing air traffic from taxiing to take-off is provided using graph theory and Z notation. After definition of airport surface by the graph structure in terms of nodes and edges, formal specification of taxiways, aircrafts and runways is provided in static part of the model. The state space analysis is provided by describing optimal paths in dynamic model expediting the departure procedure. The safety properties are described in terms of invariants over the data types carrying critical information. Further, the safety is insured by defining pre- and post-conditions in description of operations for changing state space of the system. The proposed study is focussed more on the safety component; however, the efficiency of the system is not ignored. For example, the model is based on the next generation ATC systems that use new technologies expediting the procedures. Graph theory is used in our model under the Z specification that is a foundation for automating the procedure in our future work. Formal specification is analysed and validated using Z/Eves tool. It is observed that weaknesses of testing and simulation can be overcome by applications of formal techniques avoiding state space explosions problems in complex systems.