Escaping Microburst with Turbulence: Altitude, Dive, and Pitch Guidance Strategies

Abstract

Three escape strategies are compared for microburst encounters during e nal landing approach: altitude guidance, dive guidance, and pitch guidance. The main difference between pitch guidance and the other two strategies is that pitch guidance immediately attempts to increase altitude at the expense of airspeed, whereas dive and altitude guidances initially trade altitude for airspeed. We use a full, six-degree-of-freedom, nonlinear, rigid-body aircraft model, including the effects of windshear and wind vorticity, and a model of microburst with turbulence. We also model the effect of stall prevention on the escape path. Two different approaches are used for comparison: 1) In a sample analysis approach, typical samples of the time histories of various variables are analyzed. 2 ) In a statistical approach, the probability distribution of the minimum altitude is estimated by the Monte Carlo method when the statistical properties of the microburst parameters are known. In the sample analysis and statistical approaches, the simulations take into account turbulence in addition to windshear. Both approaches suggest that, within the modeling assumptions presented, and in the absence of human factors, altitude and dive guidance with low commanded altitude may provide better safety than pitch guidance.