| 英文摘要: | This report summarizes a selection of the defense acquisition literature from the 1960s to the present on potential sources of prolonged acquisition cycle times and schedule growth, as well as potential opportunities for improvement. It presents the range of possible causes of schedule-related problems and various recommendations cited for improving schedules by various authors and organizations. This report does not provide critical analysis or an assessment of the strengths or weaknesses of the claims made in the literature. Rather, it provides a starting point for further research or consideration by government acquisition professionals, oversight organizations, and the analytic community. We identified the following reasons for schedule delays in the literature: (1) the difficulty of managing technical risk (e.g., program complexity, immature technology, and unanticipated technical issues), (2) initial assumptions or expectations that were difficult to fulfill (e.g., schedule estimates, risk control, requirements, and performance assumptions), and (3) funding instability. The most commonly cited recommendations for reducing cycle time and controlling schedule growth in the literature are strategies that manage or reduce technical risk. Some of those recommendations include using incremental fielding or evolutionary acquisition strategies, developing derivative products (rather than brand-new designs), using mature or proven technology (i.e., commercial, off-the-shelf components), maintaining stable funding, and using atypical contracting vehicles. |