“Systems engineering is an overarching discipline, providingTechnical/Social InterrelationshipsLifecycle/Social InterrelationshipsProduct Development1Engineering Systems: An Aircraft Perspective Earll M. Murman Thomas J. Allen Abstract Engineering has, in recent decades, taken on the development of systems of larger and larger scale and increasing complexity. Many examples can be found in transportation, defense and power generation. Such systems, because of their size and complexity often have human or social considerations that must be accounted for, in their design. This paper will treat aircraft as exemplars of Engineering Systems with the objective of providing a better understanding to the theoretical underpinnings of this newly developing discipline. The analysis considers a framework comprising three dimensions - Technical, Social and Lifecycle - each composed of substructure which characterizes aircraft. An observation is put forth that interrelationships within and between the substructures of these dimensions, and among the dimensions, are critical. With the engineering systems framework in mind, consideration is given to the aircraft product development process for creation of lifecycle value. A value creation framework recently presented in Lean Enterprise Value: Insights from MIT’s Lean Aerospace Initiative (Murman, Allen et.al., 2002) ) is introduced. The preliminary thinking captured in this paper may serve as a useful starting point for deeper analysis and study of aircraft engineering systems, and perhaps other domains. Introduction. Engineering has, in recent decades, taken on the development of systems of larger and larger scale and increasing complexity. Many examples can be found in transportation, defense and power generation. Such systems, because of their size and complexity often have human or social considerations that must be accounted for, in their design. This human/social interface creates a set of boundary conditions that are not normally (or easily) considered by the engineering science approach that has dominated education for the past 50 years. This approach, while it has made and continues to make significant contributions to education and practice, is reductionist in nature and normally ignores or treats as constant the human/social boundary values of this engineering problem. This is an issue that has come increasingly to concern engineering educators and practitioners in recent years. In what has become the traditional manner in engineering, practice is leading education in this matter. Engineers designing large scale systems have been forced to go beyond what they learned in school and take account of these factors in their designs. Educators are now taking cognizance of this and introducing new courses and programs dealing with engineering systems. In order for these new programs to be effective, we must now develop an intellectual basis for understanding the nature of engineering systems. We are presently a long way from that goal. Murman and Allen September 2, 2003 Draft2 In the present paper, the authors hope to provide a small step toward understanding, by examining one type of complex system, an aircraft, and examining the nature of its human/social interfaces at different levels of social and technical complexity. It will be seen how modern aircraft design must be centrally concerned with the human/social aspects, as these often present the most difficult parts of the design problem. Engineering Systems Framework By almost any measure one would choose to examine, e.g. part count, cost, number of subsystems, product lifetime, etc., aircraft are technically sophisticated, large scale products. Large organizations comprising many functional areas develop and produce aircraft, and they have extended enterprises encompassing thousands of suppliers. Aircraft also have important societal impact, being central to the movement of people and goods and to national defense. Arguably, they also have significant environmental impact at both the community level (noise, emissions) and the global level (emissions, resource consumption). With aircraft lifetimes measured in decades, decisions made early in their product lifecycle have impact for many years. For these reasons, aircraft represent an informative example of an engineering system. Based on the authors' insights, a framework composed of Technical, Social and Lifecycle dimensions is proposed to characterize engineering systems within the context of aircraft. The dimension representing the technical realization of the system is comprised of six levels ranging from individual parts or lines of code to the global environment. The social dimension embodies all the stakeholders - from individuals to society - again in six levels. The third dimension called lifecycle represents the time axis of the framework, from first concept to final disposal of the aircraft. Lifecycle aspects of both the physical and the social dimensions are important. One might suggest that a dimension representing economics is also needed. However, the technical dimension encompasses cost elements and the social dimension encompasses stakeholder value expectations. Together these represent the important drivers of engineering system economics. It is therefore suggested that aircraft engineering systems can be mapped into this three dimensional Technical-Social-Lifecycle space for analysis. More important than the sheer scale of these dimensions are the interrelationships - the “inters” - that exist between the dimensions, or between levels within the dimensions. Interrelationships within the technical dimension are a well known aspect of systems engineering (e.g. see INCOSE 2000) and will not be dwelt upon in this paper. While it would be interesting to examine the interrelationships within the social dimension, that would be a more likely topic for a paper on organizational sociology, per se. In this paper, we are beginning from a base of a complex technical system and examining the interrelationships of the technical and lifecycle aspects with the social world. Murman and Allen September 2, 2003 Draft3An interrelationship is a “mutual or reciprocal relation or relatedness”.1 Interrelationships are many and varied, and might be characterized by: • Interconnection: “a state of being connected reciprocally” or Interface: “a surface forming a common