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Toward Efficient and Effective Software Sustainment, Second in a Series

Mike Phillips

In my preceding blog post, I promised to provide more examples highlighting the importance of software sustainmentin the US Department of Defense (DoD). My focus is on certain configurations of weapons systems that are no longer in production for the United States Air Force, but are expected to remain a key component of our defense capability for decades to come, and thus software upgrade cycles need to refresh capabilities every 18 to 24 months. Throughout this series on efficient and effective software sustainment, I will highlight examples from each branch of the military. This second blog post describes effective sustainment engineering efforts in the Air Force, using examples from across the service's Air Logistics Centers (ALCs).

A Brief History of Software Sustainment

From its earliest days, the military has provided facilities to maintain the functionality of its various weapon systems. The descriptive terms for these units have included "arsenals," "depots," and "logistics centers," to name a few. In the 1990s the Air Force consolidated its depot maintenance capabilities into three centers: Warner-Robins ALC in Georgia, Oklahoma City ALC in Oklahoma, and Ogden ALC at Hill Air Force Base (AFB) in Utah. A 2012 initiative within the Air Force Material Command will centralize the leadership of the ALC's into a single entity, although the three sites will remain as sister units in a single "super ALC" headquartered at the Oklahoma City site.

Within this geographical framework, we can overlay the increased importance of software in our weapon systems. Lloyd Mosemann, the deputy assistant secretary of the Air Force for communications, computers and support systems, was a visionary leader for software sustainment in the Air Force logistics arena in the 1980s. He recognized that the various ALCs would "inherit" responsibility for the various weapon systems as production waned and that "software sustainment" should be a well-developed capability within the organic structure of the ALCs. The first demand for an organization to achieve a maturity level was in a memorandum from Mosemann to the centers, directing them to achieve a maturity level 2 against the Capability Maturity Model for Software and then, level 3 a few years later (many think the "Mosemann letter" was aimed at industry, but it was not).

This blog posting highlights examples of effective sustainment of software intensive systems across the three sites and recognizes that the successes achieved are the results of improvement efforts across the domain, well beyond the process domain. The workforce has grown in its technical competence, and a modern systems engineering environment has been developed. With that historical perspective, we can explore some of the examples evident today.

In the mid 1970s, the Air Force created a "block" strategy as a way to pursue modernization while maintaining a relatively stable production approach. In the past, letter identifiers after the aircraft number showed a change to a new capability, including major hardware changes. With increasing software content, a block upgrade represented major functionality changes with relatively modest hardware configuration changes. The block strategy has become a common practice across the DoD, where software updates are released as a block of changes at regular intervals to avoid too many variations being sent to the field. By applying a block strategy, the DoD assures that there is a regular, anticipated opportunity to have the freshest capabilities deployed.

The US Air Force F-16 program is an excellent example of the block strategy, with more than 4,400 F-16's being produced and flown by 26 countries. A key program decision made early in the development of the F-16 was the deliberate strategy for evolving the F-16's capabilities. This strategy was called the F-16 Multinational Staged Improvement Program (MSIP) and involved the continual enhancement of new aircraft and the retrofit of previous aircraft with system hardware and software capabilities. The Ogden ALC's experience with the F-16 provides a good example of the success of the MSIP being applied in a sustainment environment.

From a sustainment perspective, the focus has been on the F-16C/D, Block 30, since the later blocks (40 and 50) have remained in production.

Continuous Improvement

Initially the Ogden ALC used the CMM and then CMMI to guide its improvement efforts. More recently, they have joined their process improvement partners at the Navy Air Warfare Center at China Lake, Calif. in using the Team Software Process (TSP). The metrics produced by the Ogden team illustrate the following quality performance:

  • Major upgrades continue to enjoy higher and higher productivity due to the quality emphasis contained in the disciplined approach to software production.
  • Rework effort is down below 10 percent.

Efficient Upgrade Planning

Part of the effective planning highlighted above was an effort to provide reasonably sized updates on a regular schedule. For the F-16, the size has been about 500 thousand of source/software lines of code (KSLOC) using an upgrade cycle aimed at 18 to 24 months. The upgrade team has been able to accommodate high priority upgrades, such as a rapid introduction of the AIM-9X, by balancing sustainment and modernization loads effectively. The F-16 team has just begun to assimilate the transition of the later F-16 blocks 40 and 50. The foundation established with the Block 30 experience should enable the ALC sustainment team to master the learning curve for the more complex and diverse fleet being transitioned.

The Airborne Early Warning & Control Systems (AWACS), which are supported by the Oklahoma City ALC, provide another example. These systems fit in a Boeing 707-based aircraft with a large saucer shaped antenna housing radar systems that can be upgraded to improved hardware and software capabilities. Reflective of many DoD platforms, the AWACS system entered operations in 1976 and its critical mission systems are continually upgraded to extend its capabilities. The multi-source integration function that is part of the most recent AWACS upgrade used open systems and lean architecture approaches, which are advocated by the SEI and allow more rapid software updates to the fleet without requiring extensive hardware changes.

Another weapon system sustained and continuously improved upon at Oklahoma City is the venerable B-52 strategic bomber. If planned modernization efforts of this weapon system extend the life as currently proposed, the aircraft will have been in the active Air Force inventory for almost 90 years upon its retirement in 2040. The improvement to the software architecture expands its versatility with "smart weapons" and its network communications capability. In an era that demands a focus on affordability, extending the lifetime of the B-52--while enhancing its capability--demonstrates the power of software-focused modernization.

The Warner-Robins ALC has responsibility for electronic warfare and radar systems, as well as weapon systems, including the F-15, C-130 (almost as old as the B-52) and the C-5. Across this collection of software-reliant systems, the center continues to improve the quality and timeliness of its upgrades. Of 246 software releases in fiscal year 2010, the ALC delivered 99 percent at or below expected cost, and 98 percent on or ahead of schedule. Only three systems contained defects that were discovered in the field after release and required rework. As with its two sister ALCs, Warner-Robins has committed to continuous improvement of its software capability. While we at the SEI are pleased with the unit's involvement with our CMMI models, the organization has complemented that effort with attention to Lean Six Sigma and the Air Force Smart Operations for the 21st Century (AFSO21). The results are notable.

The leadership of the software organization at Warner Robins has noted that the "old image" of software sustainment as small "bug fixes" has been replaced by recognition that with software-reliant systems, the opportunity arises to quickly develop innovative capabilities to solve the challenges facing their DoD--and allied nation--customers today.

Each of the services has a wide variety of software-reliant systems, and organic capabilities to complement the major contractors who create sturdy platforms like the B-52 that can last nearly a century. The next installment in this series on efficient and effective software sustainment will examine the Naval Air Weapons Station at China Lake.

Additional Resources

To read the SEI technical report, Sustaining Software Intensive Systems, please visit


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