The danger of natural and triggered lightning has a significant impact on space launch operations at the USAF’s Eastern Range (ER) and NASA’s Kennedy Space Center (KSC). One third of launch countdowns from the ER and KSC are scrubbed or delayed by weather. The ER and KSC are located on the east coast of central Florida, near the area of maximum lightning activity in the United States. The lightning Launch Commit Criteria (LCC) are a set of rules used to avoid the lightning threat to launches from the ER and KSC. If a LCC is violated, then the launch is delayed or scrubbed.
This paper presents a brief overview of the lightning LCCs. The current LCCs and their impact on launch operations are discussed, including the triggered lightning process. Triggered lightning is an electrical discharge caused by the rocket and electrically conductive exhaust plume passing through a sufficiently strong already existing electric field. The historical development of LCCs and the LCC change process are also presented. The LCCs are a set of rules describing weather conditions which indicate a possible lightning threat to rockets. The eleven rules are as follows: 1) lightning, 2) cumulus cloud, 3) anvil cloud, 4) debris cloud, 5) disturbed weather (moderate precipitation and melting level), 6) thick cloud, 7) smoke plume, 8) surface electric field, 9) electric field aloft, 10) triboelectrification, and 11) "Good Sense Rule". The LCCs have evolved extensively over the past three decades. They were established after Apollo 12 was struck twice by triggered lightning during launch in 1969, and extensively upgraded after Atlas Centaur 67 was destroyed by triggered lightning in 1987. The first step in the LCC change process is a consultation with or recommendation by the Lightning Advisory Panel (LAP), an independent group of atmospheric electricity experts from universities, government agencies, and industry. The LAP’s recommendations are reviewed by the Inter-Agency Coordinating Council; approved by the Joint USAF/NASA Range Safety Panel, NASA, USAF Ranges, and launch contractors; and finally implemented operationally in coordination with the launch customers.
The lightning LCCs are evaluated and forecast operationally by the USAF 45th Weather Squadron for over 40 launches per year. Launch customers include the DoD, NASA, and commercial customers for over 40 launches per year ofusing Titan, Atlas, Delta, Athena, Pegasus, and Space Shuttle rockets, and Trident ballistic missiles
The 8th Conference on Aviation, Range, and Aerospace Meteorology