The current European Air Traffic Management (ATM) system will be unable to cope with the projected increase in air traffic, and there is a need to ensure that its evolution through new technologies, structures, procedures and functions, in order to increase capacity, is not to the detriment of safety. Current methodologies consider safety, efficiency and capacity as separate parameters and do not attempt to express the relationship between them. There is therefore a requirement to address methodologies and develop indicators for safety, efficiency and capacity assessment across the spectrum of operational and functional needs of ATM.
The main project objectives were:
- to investigate methodologies/techniques, tools and indicators for measurement and optimisation of safety, efficiency and capacity of ATM systems during design, implementation and operation;
- to elaborate a unifying framework for assessing the effect of structural, procedural and functional aspects of new systems on safety, efficiency and capacity;
- to provide a consistent database for a future study about safety, efficiency and capacity.
The project has achieved the major aim of clarifying the interdependency of safety, efficiency and capacity in ATM systems. Methodologies and indicators which assess ATM safety, efficiency and capacity have been identified, and in-depth analysis of those which are significant together with a unifying assessment framework have been provided. The main conclusions are:
- since safety is, for overriding social and ethical reasons, considered as the dominant factor, there is the implication that other factors, such as efficiency and capacity, must always be evaluated with respect to a given target level of safety;
- safety, efficiency and capacity must be continuously monitored to allow their evolution throughout the system life-cycle; this process of vigilance and review covers all system aspects from user actions and human-machine interfaces through operational procedures to hardware and software functionality;
- systems should be designed to facilitate this monitoring, and formal requirements for this should be invoked in procurement specifications;
- safety case methods are superior to methods producing a single overall risk parameter;
- capacity and efficiency analysis is best approached by simulation methods;
- utility value analysis provides an effective framework for the assessment of interactions between safety, efficiency and capacity.
The SECAM study has consolidated existing experience and proposed a direction for further analysis of safety, efficiency and capacity assessment methodologies. The formalised SECAM method based on a utility value approach provides a method to weigh and synthesise historical evidence, design parameters and expert opinion to produce an assessment of the relative merits over several options. Civil aviation authorities, manufacturers and airlines could use the results to assess the impact of the incorporation of new systems.
Recommendations have been made for further work. The first priority is the further validation of the SECAM framework on a set of realistic case studies. A second is to refine the SECAM framework and provide supporting tools. Other priority investigations are the further development of safety case methods for ATM, assessment of system safety, efficiency and capacity by simulation under extreme conditions, and development of SECAM based formal requirements.