tions of this issue are discussed in Chapter 4. In this report, we use only the terms “evolutionary acquisition” and “staged acquisition.”

Reducing acquisition time and costs is a problem of great importance to DoD, as it often takes a decade or longer to complete the development and delivery of new major military systems. Even a small reduction in the costs of an ACAT I (acquisition category I) system provides significant savings in program costs. One reason given for delay in the development of complex defense systems is the phenomenon of “excessive requirements.” These can be overly optimistic initial expectations of what can be achieved, or they can be add-ons to the initial requirements, revisions of specifications, or changes in designs that occur during development and production. While most of these requirements are well intentioned, the net result is often significant slippage in development schedules (thereby delaying delivery of the capability to users in the battlefield) and substantial increases in procurement costs.

Evolutionary acquisition has been advocated as a way to address these problems. The stages of evolutionary acquisition may correspond to new hardware and software capabilities, increased performance, or to system improvements traced to technological maturity and reliability growth advances. If the acquisition program actually encompasses a “system of systems,” then the stages can provide for an increase in the capabilities or performance levels of individual systems, or they can represent new systems that are incrementally added to the system of systems. With evolutionary acquisition, initial and intermediate versions of the system will be released to the field if the decision is made that the system at that stage is superior to those currently in use. For this process to work, however, the initial system architecture must be designed so as to allow for the incorporation of changes dictated by the capabilities or improvements at later stages.

The evolutionary acquisition framework ideally allows for a fielded system to undergo further improvement without initiating a new procurement program. Thus, new technologies (particularly software) can be quickly deployed to enhance capabilities in the field, providing flexibility in responding to changing military missions, threats, and operating environments. By comparison, the traditional acquisition process, with its long lead times, often results in buying systems containing technologies that are outdated when finally fielded.

The idea of modifying fielded defense systems to improve their performance is, of course, not new. The Services have been developing substantial upgrades to existing defense systems for many years. However, many of