The department of Electronic Warfare Assessments at the Swedish Defence Research Agency (FOI) in Linköping, 1999 got the commission to make a study about "VMS", Warning and Countermeasure System for helicopter. The study would among other things result in simulation software "Terrängmodell Upptäckt". This simulation software would be used to run simulations where the helicopters risk for detection and being shoot down is studied. This thesis presents the work with the design and the implementation of that part of the "Terrängmodell Upptäckt" which calculates and presents what state the helicopter has in relation to specified threatsystems during the helicopters flight through the 3D-terrain. The simulation software consists of a C++ program connected to Vega. Vega is a COTS product containing a 3D-engine and a tool for scene generating. Calculations to decide the state of the helicopter are made from line-of-sight calculations and system times. What state the helicopter has in each coordinate is presented by a colored trail behind the helicopter in the 3D-visualization. The result of the thesis is the implementation of the state calculating part and the presentation of what state the helicopter has. Example of simulation runs can be found in appendix A.