Approach and landing are among the most challenging and dangerous tasks required of helicopter pilots. Helicopter accident statistics suggest that the majority of helicopter accidents in the U.S. occur during either the approach or landing phases of flight and that unstabilized approaches are a leading cause due to the associated increased potential for loss of control, loss of situational awareness, or controlled flight into terrain. In the present work, routine flight data records obtained as part of a voluntary helicopter flight data monitoring program are used to identify, analyze, and evaluate approach events in a variety of helicopter flights from different mission types, such as emergency medical services, flight training, and research. A semi-automated process is developed which enables detection of the approach phase, construction of a nominal approach path, analysis of approach stability, and knowledge discovery through data mining. The process was able to identify 3950 visual and 183 instrument approaches in a set of 3749 operational helicopter flight data records. Analysis of visual approach events suggests that typical approaches are higher and steeper than expected. Thus, the traditional definition of a stabilized approach may not align with typical operations. Additionally, atypical approaches can be classified as highly stabilized, marginally unstabilized, or unstabilized depending on their associated stability measures.
Robinson, J. N., Payan, A. P., Johnson, C., and Mavris, D. N., “Visual and Instrument Helicopter Approach Stability Analysis Using Data Fusion and Data Analytics”, AIAA SciTech 2021 Forum, American Institute of Aeronautics and Astronautics, 2021, https://doi.org/10.2514/6.2021-0528