Natural and triggered lightning launch commit criteria

Because natural and triggered lightning are serious threats to both manned and unmanned space launches, NASA and the USAF have adopted several lightning launch commit criteria (LLCC) that will hold (delay) a launch when one or more of the following hazards exists over or near the launch site: 1) any type of lightning within 10 nautical miles, 2) any cumulus clouds that are likely to contain (or produce) high electric fields, 3) any attached or detached thunderstorm anvils, 4) any thunderstorm debris clouds, 5) any nontransparent clouds that are precipitating due to disturbed weather, 6) any thick layer clouds that encompass the 0 °C to -20 °C temperature levels, 7) any cumulus clouds that are attached to large smoke plumes, 8) any clouds that produce high electric fields at the surface, and 9) any clouds above the -10 °C temperature level that could produce triboelectrification on the surface of the vehicle. In this presentation, we will review the reasons for the above LLCC, and we will describe some on-going efforts to improve them using recent airborne measurements.