Airborne infrared low-altitude wind shear detection test

Abstract

Strong wind shears at low altitudes present severe hazards to aircraft during landing approach and takeoff. With aircraft operating near stall speed, a significant change in the wind speed and/or direction can result in a rapid loss or gain in altitude. Our objective is to describe the test of a prototype system for airborne, advance detection of such wind shear by means of infrared remote sensing. The test was conducted during the Denver Joint Airport Weather Studies (JAWS) project in the summer of 1982 aboard the NASA Ames B57B jet aircraft during several landing approaches and departures. The intent is to present analyses of the major results of this test and suggest its application to the passive, airborne detection of hazardous low-altitude wind shear (LAWS) before an aircraft encounter. This is critical for aircraft operating in an out of airfields without LAWS ground warning systems. This airborne wind shear detection and avoidance system is intended to augment the advanced, ground-based microwave, lidar, and low-altitude wind shear alert equipment as a secondary, airborne system. Even at distances as great as 12.5 miles (20 km) from thunderstorms, the wind shear in storm density currents can pose a real hazard to approaching and departing aircraft. It is concluded that the prototype airborne radiometer, observing in the 13 to 16 ^m portion of the atmospheric molecular spectrum of CO2, can sense the cold current outflow or gust front directly associated with low-altitude wind shear (LAWS) in the vicinity of thunderstorms at ranges up to 4 miles.