Using Mathematical Modeling to Identify the Impact of Proposed Structure on Nearby Instrument Landing System

SST conducted a study of the impact of three proposed warehouse buildings on nearby instrument landing system (ILS) navigational aids (NAVAIDs) at the Dallas/Fort Worth International Airport.

SST applied computer simulation using mathematical modeling and post processing data analysis during the planning stages of construction. The study included predicting the resulting performance of two localizers and one glide slope that are part of the ILS supporting Runways 17L and 35R. SST’s advanced modeling and post processing efforts were able to account for existing NAVAID performance by using the most recent flight inspection data for each NAVAID and combining this existing impact with modeled impacts of the proposed buildings to generate an accurate overall performance prediction for each NAVAID while the buildings are present. Geometrical ray tracing and flight profile analysis determined the proper modeling approach to use for determining signal scattering services of interest as well as how to best model the gradually sloping ground plane. Extensive modeling determined the most cost efficient and effective methods of mitigation for the two NAVAIDs that were shown to be significantly impacted by the proposed construction, including changing the localizer from a 14/10-element system to a 20-element configuration and optimizing the glide slope performance before rotating the glide slope antennas 8 degrees towards the runway threshold. These two mitigation efforts have shown positive results for dealing with the introduced impact of the buildings. Post-processing analysis helped to generate illustrative heatmaps to determine the best areas for crane and drilling rig storage during non-construction time periods.

This simulation study identified many key points of interest for stakeholders and engineers in the field. The combining of existing and proposed impacts to the studied NAVAIDs allowed for a clearer overall performance summary, as well as helped to investigate the reliability of proposed mitigation options. Performance impact heatmaps helped to illustrate the best construction equipment parking locations. The continual supply of step-by-step modeling support helped to verify predicted NAVAID impacts and being sure that the latest flight inspection results are being used to generate the overall performance predictions.