Target pitch angle for the microburst escape maneuver

Commuter and general aviation aircraft face no less a threat from microburst wind shear than do large jet transport aircraft, yet the majority of flight dynamic research has emphasized recovery performance and piloting techniques for jet transport aircraft. The current work investigates the effects of microburst wind shear on propellerdriven commuter-type aircraft. Recovery performance of a commuter-type aircraft in a microburst encounter is examined using a constant-pitch-attitude strategy and flight path optimization. The goals are to identify a suitable target pitch angle for the escape maneuver and to determine the nature of an optimal escape maneuver for a commuter-type aircraft. The results demonstrate that the pitch attitude which maximizes climb rate in a wind shear condition is strongly dependent on whether the aircraft is subjected to a horizontal shear or a downdraft. Simulated constant-pitch-attitude recoveries through an analytic downburst model show that the pitch attitude which maximizes ground clearance, depends on the altitude of the encounter, the strength of the microburst, and the initial position of the aircraft with respect to the downburst core. In severe wind shear encounters at very low altitudes, best results are obtained at relatively low-target pitch angles (TPA). Excessively high-target pitch angles subject the aircraft to prolonged periods at stall warning angle of attack. The flight path optimization demonstrates that a technique which maximizes ground clearance involves maintaining a low-pitch attitude early in the encounter, followed by a gradual pitch-up that ceases when the wind shear has been exited.