To quantify the hazards induced by air traffic to non-involved third-parties, like residents and employees in close vicinity to airports, the “External Risk Model” is used. Based on the theory of probability, this creates a connection between the probability of aircraft presence at a specific location of the investigated area, the probability of an accident at this location and the resulting destructive potential, including existing hazardous equipment on the ground such as fuel or gas storages.
In essence, these functions are calibrated through empiric data collection as well as mapping of energetic characteristics of propagation at different topographic conditions. The results of the calculation procedure are statements about the probability with which a person, permanently residing at the correspondent position, perishes as a result of an aircraft accident.
In the context of current planning approval procedures, one detail investigation is particularly important: the influence of incident systems according to SEVESO II onto the external risk in the vicinity of the airport - especially near the approach and departure routes. In the case of an internal or external disturbance of the normal operation, such systems also pose a health risk to persons who reside outside the factory premises. With the help of physical incident models developed in cooperation with system experts, a detailed simulation of possibly triggered secondary events besides the actual primary event (aircraft accident) is also possible.
By now, the available calculation methodology is requested by national and international licensing authorities as a key instrument for assessment of environmental impact, spatial planning and ability for approval of extensive and new construction projects in the airport sector. Despite the lack of legally established limitative values, the methodology allows a specification of relative valuations based on quantitative results.
The model has been used extensively and successfully in the context of the planning approval for the construction of a fourth runway at Frankfurt/Main Airport. Due to its high achievable reproduction accuracy the External Risk Model was able to successfully compete against alternative methodological calculation methods of other international competitors.