FAA/Military regulations require facility planners/managers to identify obstructions to air navigation and establish airfield safety clearances for fixed wing aircraft and helicopters. This is accomplished by constructing airport imaginary surfaces, in accordance with required regulations, for each runway or landing pad and then evaluating obstructions to determine if any safety clearance violations exist. In addition, notifications of proposed construction that may affect navigable airspace must also be evaluated. With the boom in construction of cellular towers, digital TV towers, antennas, etc., the evaluation of obstructions is a never ending, time-consuming, and often expensive task. By utilizing ArcView GIS to automate this process, facility planners/managers can construct airport imaginary surfaces and evaluate obstructions quickly, accurately, and inexpensively. Notifications of proposed construction may be evaluated in seconds with just a click of the mouse. Add in ArcView 3D Analyst and facility planners/managers have the capability to display and analyze a three-dimensional visual representation of the relationship between airport surfaces and obstructions. One final note of interest is the prospect of utilizing ArcView GIS to automate the development and obstruction evaluation of terminal instrument approach procedures (TERPS), in the same manner as airport imaginary surfaces.