Airborne Warning Systems for Natural and Aircraft-Initiated Lightning

Possible airborne warning systems other than radar for avoidance of thunderstorms and lightning strikes to aircraft can include one or more of the various types of instruments surveyed here. One class of warning system considered is concerned with lightning strikes initiated ("triggered") by the aircraft itself when in high-field environments within electrified but "nonthundery" clouds. Since data show high correlations between strikes to aircraft and high-field environments, warnings can be provided by various types of field detectors considered. The other class of warning system is concerned with distant thunderstorm warnings provided by the many different types of RF sferics detectors considered, and by optical detectors. The sferics detectors sense electromagnetic fields radiated by lightning and by prelightning discharges. They include crossed-loop, multipleloop, time-of-arrival, interferometer, pulse-height, spectral-amplitude, and E- and H-amplitude systems. Direction-rinding errors are discussed in detail, especially site errors (generally unrecognized) of crossed loops mounted on aircraft. Theoretical assessments of the latter are made using analytical models as well as a 3-dimensional computer model to simulate aircraft structures.