The Lean Aerospace Initiative and the Lean Aerospace Initiative Consortium define processes applicable in many domains for applying lean. At first glance there is no natural connection between Lean and System Engineering. The ideas below are from a paper Igave at a Lean conference.
- Lean and Systems engineering are cousins.
- All but trivial projects are systems and many are systems of systems. Thinking like a systems engineer is the basis of implementing Lean processes. Thinking in the absence of systems, does little to add sustaining value to any process improvement.
- Product development is a value stream process, but how the components interact at the technical, business, financial, and operational levels is a systems engineering process. Lean itself does not possess the vocabulary to speak to these systems complexity issues 
Core Concepts of Systems Engineering
- Capture and understand the requirements in terms of Capabilities assessed through Measures of Effectiveness (MOE) and Measures of Performance (MOP).
- Ensure requirements are consistent with what is predicted to be possible in a solution in these MOEs and MOPs.
- Treat goals as desired characteristics for what may not be possible.
- Define the MOE, MOP, goals, and solutions for the whole lifecycle of the project in units meaningful to the buyer.
- Maintain the distinction between the statement of the problem and the description of the solution.
- Baseline each statement of the problem and the statement of the solution.
- Identify descriptions of alternative solutions.
- Develop descriptions of the solution.
- Except for simple problems, develop a logical solution description.
- Be prepared to iterate in design to drive up effectiveness.
- Base the solution of the evaluation of its effectiveness, in units of measure meaningful to the buyer.
- Independently verify all work products.
- Validate all work products from the perspective of the stakeholders.
- Some management is needed to plan and implement effective and efficient transformation of requirements and goals into a description of the solution.
Typical System Engineering Activities
- Technical management
- System design
- Product realization
- Technical analysis and evaluation
- Product control
- Process control
- Post implementation support
Steps to Lean Thinking 
- Specify value
- Identify value stream
- Make value flow continuously
- Let customers pull value
- Pursue perfection
Differences and Similarities between Lean and Systems Engineering
- Both emerged from practice. Only later were the principles and theories codified.
- Both have focused on different phases of the product lifecycle. SE is generally on product development. SE is more focused on planning. Lean generally on product production. While Lean is more focused on empirical action.
- Unlike Lean, SE has less focus on quality, except for Integrated Product and Product Development (IPPD).
Despite these differences and similarities both Lean and Systems Engineering are focused on the same objectives – delivering products or lifecycle value to the stakeholders.
It is the lifecycle value that drives both paradigms and must drive any other process paradigm associated with Lean and Systems Engineering. Paradigm like software development, the management of any form of a project and the very notion of agile. A critical understanding often missed is that Lifecycle Value includes the cost of delivering that value.
Value can't be determined in the absence of knowing the cost. ROI and Microeconomics of decision making require both variables to be used to make decisions.
What do we mean by lifecycle?
Generally lifecycle is a combination of product performance, quality, cost and fulfillment of the buyers needed capabilities.
Lean and Systems Engineering share this common goal. The more complex the system, the more contribution there from Lean and SE.
Putting Lean and Systems Engineering Together on Real Projects
First some success factors on complex projects 
- Dedicated and stable interdisciplinary teams
- Use of prototypes and models to generate tradeoffs
- Prioritizing product features
- Engagement with senior management and customers at every point in the project
- Some form of high performing front end decision process that reduces instability of key inputs and improve the flow of work throughout the product lifecycle.
This last success factor is core to any complex environment, no matter what the process is called. In the absence of stability of requirements and funding, improvements to the flow of work is constrained.
The notion of adapting to changing requirements is not the same as having the requirements – and the associated funding – be unstable.
Mapping of the Value Stream to the work process requires some level of stability. It is the search for this stability where Systems Engineering – as a paradigm – adds measureable value to any Lean initiative.
The standardization and commonality of processes across complex systems is the basis for this value. 
- Lean and SE are two side of the same coin regarding the objective of creating value for the stakeholder
- Lean and SE complement each other during different phases of the project – ideation, product trades for SE and production waste removal for Lean anchor both ends of the spectrum of improvement opportunities.
- Value stream thinking makes visible the paths to be taken in transitioning to a Lean paradigm while maintaining the principles of systems engineering. 
- The result is the combination of Speed and Robustness – systems are easily adaptable to change while maintaining fewer surprises, using leading indicators to make decisions and decreasing sensitivity to production and use variables.
 “The Lean Enterprise – A Management Philosophy at Lockheed Martin,” Joyce and Schechter, Defense Acquisition Review Journal, 2004.
 Lean Thinking, Womack and Jones, Simon and Schuster, 1996
 Lean Enterprise Value: Insights from MIT’s Lean Aerospace Initiative, Murman, et al, Palgrave 2002.
 “Lean Systems Engineering: Research Initiatives in Support of a New Paradigm,” Rebentisch, Rhodes, and Murman, Conference on Systems Engineering, April 2004.
 LM21 Best Practices, Jack Hugus, National Security Studies, Louis A. Bantle Symposium, Syracuse University Maxwell School, October 1999
 “Enterprise Transition to Lean Roadmap,” MIT Lean Aerospace Initiative, 2004 Plenary Conference.