A spiral guidance approach concept for commercial VTOL operations

The results of an investigation of the guidance and navigation requirements for VTOL spiral descents in the presence of winds are reported. Models were developed to describe the spiral maneuver and candidate guidance laws were formulated and analyzed. An important element of the guidance scheme is a unique wind estimator which uses the perturbations in bank angle and heading to improve the knowledge of the winds. Finally, recommendations for additional research, including a flight program, were outlined to evaluate the spiral guidance concept.