Marco conceptual

The development of the LLCC and their associated Definitions in the post-AC 67 era has been an ongoing process of collaboration between the LAP (originally the PRC), the NASA/KSC Weather Office (originally the NASA-HQ Weather Support Office), and the Air Force 45WS. As we have seen, the first set of lightning launch commit criteria was developed in the wake of the Apollo XII incident, after it was recognized that a launch vehicle can trigger lightning. After this incident there was considerable involvement of the scientific community at large, and the resulting LLCC were detailed by the Apollo Program in its official accident investigation (NASA, 1970, p.50). Thereafter, the LLCC evolved gradually and without formal coordination over a succession of manned and unmanned vehicles until the AC 67 accident. This event demonstrated that the triggered-lightning hazard was not being taken seriously by launch weather personnel and that the rules were not being applied uniformly.

In reaction to the AC 67 accident, a relatively small, blue-ribbon panel of experts, the "Heritage Committee," was empowered to undertake an independent study of the issues and draft a much more comprehensive and scientifically justified set of LLCC [Heritage, 1988, Chapter 7]. Shortly thereafter, a subset of the Heritage Committee was asked to serve on the first standing committee, the PRC, to evaluate and improve the LLCC (see Section 5.2.1).

Since the original formation of the PRC/LAP, a dual-track process has evolved. The LAP initiates, re-writes, or re-phrases LLCC in response to new scientific knowledge, and the LAP proposes experiments to advance knowledge in areas that are important for launch support. The LAP also receives questions and concerns about the LLCC and their implementation from launch-weather personnel (particularly the KSC Weather Office and the 45WS, and more recently the SMG, the 30WS, and even people at the Kodiak Launch Complex). Out of what might easily have become an adversarial relationship due to an imperfect science and the need to apply the LLCC in the real world, certain mutual goals have emerged, especially having rules that both improve safety and increase launch availability. This process has resulted in growing confidence in, and attention to, the LLCC and the associated Definitions. In this chapter we try to summarize the most significant conclusions and recommendations that have emerged from this process.

Summarized in a single sentence, the LLCC must be safe, physically valid, complete, not unnecessarily restrictive, self-consistent, clear, and faithfully implemented. Each of these requirements and its importance is briefly elaborated below:

Safety. First and foremost, the LLCC must be safe. No lightning strikes to vehicles during launch, triggered or natural, will occur when the rules are followed. Safety is assured by making the LLCC both physically valid and complete, as outlined in the following two sections. The LAP process for achieving these and the other goals outlined below has been discussed in Section 5.5.1 above. It bears repeating, however, that launch safety and launch availability are competing needs that must be carefully balanced.

Physical Validity. A sound physical basis for the LLCC is an obvious prerequisite for their safe and successful application. Furthermore, if individual launch rules could easily be challenged on technical grounds, they would quickly be ignored, and the whole LLCC process would lose credibility. The LAP has used the scientific literature and the outcomes of recommended experiments to ensure that the LLCC cover the meteorological conditions that will produce hazardous electric fields aloft. The science that is behind the current rules will be discussed in detail in the Rationale document that is planned to accompany this History. Completeness. Safety requires that the LLCC identify all meteorological conditions that will create high electric fields aloft. Without this completeness, accidents will occur that will call the whole process into question. Rather than risk any such accidents, the LAP has started with LLCC that are conservative, and

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additional instrumentation (e.g., field mills) has been recommended to cover unexpected conditions that might be hazardous. By identifying the sources of false alarms, and by recommending new methods of detecting and eliminating them, the LAP has incrementally reduced the initial conservatism and increased launch availability without sacrificing safety. Nevertheless, there will always be a tradeoff between completeness and launch availability in questionable weather situations.

Launch Availability. Close collaboration between the LAP, the 45WS, and the KSC Weather Office has emerged as an efficient way to identify individual launch restrictions that have a significant impact on launch availability or that appear to have an unduly high false-alarm rate. When attention is focused on these

situations, solutions can often be found that increase launch availability without compromising safety.

Consistency. There are two important aspects of self-consistency in the LLCC. 1) Within each individual rule, the sub-sections should be mutually consistent to prevent confusion and incorrect evaluation by the Launch Weather Team (LWT). This issue has been addressed with logical truth-table analysis, which can not only eliminate inconsistencies between sections of a given rule but also remove redundancy that can lead to

ambiguity. 2) Because all rules in the LLCC must be evaluated simultaneously, it is helpful, though not always possible, for each rule to be consistent with the others. There will occasionally be ambiguity over which rule applies to a given weather situation, because of the inherent subjectivity in evaluation, and in such situations all potentially applicable rules must be satisfied.. In these situations, an apparent inconsistency may worry the LWT, but if the most conservative criterion is applied, that will insure safety.

Clarity. The LLCC must be clearly written to ensure proper understanding by both customer personnel, who must accept them prior to any countdown, and the LWT, which must apply them during the launch. Because it is critical for the LWT to evaluate the LLCC quickly and accurately under pressure, the rules themselves should be as clear and easy to understand as possible. The close working relationship that has developed between the LAP and the 45WS has been invaluable for clarifying the rules and has led to more efficient operational use. Nevertheless, increased launch availability without compromising safety comes at the price of greater complexity. The desire for lower false-alarm rates has led to the addition of numerous exceptions to the basic LLCC that require additional conditions to be satisfied. The LAP has introduced truth tables to facilitate better understanding of the rules and make them self-consistent (see figures in Appendix II). These truth-tables are also beneficial as training materials.

Faithful Implementation. Even a perfect set of LLCC and definitions cannot assure safety unless they are fully and correctly applied during launch operations. The following are requirements for safe implementation: 1) The rules must be coordinated with, and certified by, all customers prior to use to ensure that they understand and accept the assumptions and associated risks. 2) The LWT must be rigorously and correctly trained, certified, tested, and routinely retested during the conditions of a launch countdown. 3) The LLCC must continue to be evaluated on the basis of data derived from a reliable, accurate, and robust weather and

atmospheric-electricity infrastructure. 4) Each member of the LWT must be clearly convinced that each of the LLCC has been completely satisfied. 5) The LWT must be managed by a Senior Weather Officer who ensures that each LWT team member is aggressively and strictly assessing the LLCC and is freely and constructively communicating data and assessments with other LWT members. 6) The Senior Weather Officer in charge must ensure that external factors like "launch fever" or visitors, especially VIPs, do not impede or bias the LWT evaluations; and that manager must handle all queries, comments, and concerns from higher headquarters and other senior management and not on the formal customer Launch Decision Team. 7) The LAP notes that the civilian Launch Weather Officers (LWOs) have made a significant contribution to launch safety through rigorous training, careful observation, and conscientious application of the LLCC. It is essential to preserve this ‘corporate memory’ by maintaining a sufficient number of civilian LWO positions.

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