Ecological risk assessment framework for low-altitude aircraft overflights: I. Planning the analysis and estimating exposure

An ecological risk assessment framework for low-altitude aircraft overfligh ts was developed, with special emphasis on military applications. The probl em formulation and exposure analysis phases are presented in this article; an analysis of effects and risk characterization is presented in a companio n article. The intent of this article is threefold: (1) to illustrate the d evelopment of a generic framework for the ecological risk assessment of an activity, (2) to show how the U.S. Environmental Protection Agency's ecolog ical risk assessment paradigm can be applied to an activity other than the release of a chemical, and (3) to provide guidance for the assessment of ec ological risks from low-altitude aircraft overflights. The key stressor for low-altitude aircraft overflights is usually sound, although visual and ph ysical (collision) stressors may also be Significant. Susceptible and regul ated wildlife populations are the major assessment endpoint entities, altho ugh plant communities may be impacted by takeoffs and landings. The exposur e analysis utilizes measurements of wildlife locations, measurements of sou nd levels at the wildlife locations, measurements of slant distances from a ircraft to wildlife, medals that extrapolate sound from the source aircraft to the ground, and bird-strike probability models. Some of the challenges to conducting a risk assessment for aircraft overflights include prioritizi ng potential stressors and endpoints, choosing exposure metrics that relate to wildlife responses, obtaining good estimates of sound or distance, and estimating wildlife locations.