What is a complex megasystem? Take Operation Enduring Freedom. It was an unprecedented collaborative engagement with networked forces. Hundreds of systems had to work together, whether they were originally designed to or not. For example, in one episode Special Operations Forces requested close air support but the Navy F-14 providing close air support was out of weapons. So the F-14 crew used onboard sensors to locate the target and pass the target data via voice to an Air Force Airborne Warning and Control System plane. Then an Air Force B-52 hit the target with precision munitions. Time to target was only 18 minutes.

This example of how complex systems engineering helped win a conflict through necessity and evolution is recounted by MITRE's Al Grasso, senior vice president and director of the Command, Control, Communications, and Intelligence (C3I) Federally Funded Research and Development Center operated by MITRE for the Department of Defense (DOD). "The DOD had no requirement or architecture that anticipated the Operation Enduring Freedom event," says Grasso. "Completing the impromptu mission was not achieved by any single system. And it may never happen again in exactly the same way. So how does an organization plan systems that are more complex and do more?"

Another example of a complex system is an Air Operations Center (AOC) that manages 24-hour schedules for a wide variety of aircraft. The AOC may contain 1,000-2,000 people, more than 100 workstations, and use 25 big applications and up to 80 smaller applications. And such a complex system must be able to rapidly adapt to threats and changing environments.

In the future, a combat system may involve 2,500 people and 1,100 platforms. It may have 160 external interfaces, more than 30 million lines of code, and with a requirement of 10 million more lines of code in two years.

Other complex systems include today's air traffic control systems and the U.S. power grid.

One view of complex systems engineering is as a subset of systems engineering, which is a subset of general engineering.

MITRE's core focus has always been systems engineering and it is our role to stay ahead of the curve in its evolution. We are looking at the best ways to design, adapt, and manage complex systems—both those now being designed and existing systems that must be made interoperable.

Systems engineering projects are becoming so complex that new ways of applying the discipline have to be devised. "These systems are referred to as systems-of-systems, enterprise systems, complex (adaptive) systems, or even megasystems," says Grasso. The "components" of such complex systems are large-scale systems in their own right and are strongly dependent on each other's actions.

"MITRE has taken on the challenge to develop a well-defined discipline for the engineering of these complex systems," says Grasso. "This will allow us to advise our sponsors on how to build complex systems effectively. For example, dealing with risk mitigation is different in complex systems than in traditional systems engineering. We need to find new ways to manage risk in systems in which applications can't be anticipated far in advance."

Another element of complex systems is that they tend to cut across multiple programs and services and thus require a great deal of collaboration. With a new system, collaboration is built into the development process. When existing systems are used together, the collaboration comes in real time, as in Operation Enduring Freedom. Today's complex systems must work with an existing inventory of hardware, software, and services. In both cases, complex systems must be able to respond to unanticipated events.

"Approaching complex systems differently in the concept phase will produce a more successful system in the end," says Brian White, director of MITRE's Systems Engineering Process Office. He believes the first step is to come up with standard definitions. "One important issue is how you define terms such as 'complex system' and 'complex systems engineering' (CSE) because this colors your approach to problem-solving," says White. "Some people have the perspective that 'engineering' encompasses systems engineering, which in turn includes CSE. Others think it depends on the degree of problem difficulty. With this perspective, CSE is more difficult than 'traditional' systems engineering, and not all the tools of traditional systems engineering apply. Something more is needed."

No matter how you define it, all agree that engineering complex systems requires a high level of adaptability. The designers cannot remain wedded to the original requirements. "In an open, complex system environment, new and/or different behaviors and capabilities will emerge. These can be expected or unexpected, desirable or undesirable," adds White. "The challenge is to manage this environment effectively. In this context the 'requirements' keep changing; the current set is based upon the most recent management decisions."

As linear systems evolve into complex systems, their predictable behavior becomes unpredictable.

Cognitive Systems and Control

Renee Stevens, a senior principal engineer at MITRE, sees the key question about complex systems as: How do you engineer and evolve a megasystem in the absence of familiar control mechanisms? "The road to complexity has gone from machines to information systems to cognitive systems," says Stevens.

"This next level of complexity involves social systems and issues of boundaries, which has implications of control," says Stevens. "With complex systems, involving many organizations, the organizational and cultural issues tend to dominate. It's not that the technology is not a challenge because in many cases we are using state-of-the-art technology. It's a matter of getting people to apply it in a consistent fashion."

Stevens sees a number of emerging ideas for megasystems engineering principles. "There will be less emphasis on requirements and more on experimentation and trial for the user," she explains. "Systems engineering for these large complex megasystems will have less emphasis on managing risk and more on managing uncertainty. In addition, there will be a focus on early discovery and evolution of composite behavior, functionality, and performance. Unknowns will be expected to emerge upon integration. Prototypes will be used much earlier."

There is much work to be done on understanding and evolving complex systems to meet the challenging needs of our sponsors. "That is why we are moving aggressively to understand and capitalize on advances in information technology that will help us leverage complex systems," says Grasso.

—by David Van Cleave

Related Information

Technical Papers and Presentations

• Engineering a Complex System

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