Generic Life Cycle Stages

A generic system life cycle is commonly described using the following stages:

1. Concept
2. Development
3. Production
4. Utilization
5. Support
6. Retirement

These stages provide a broad framework that can be tailored for different organizations, industries, acquisition models, and system types.

Concept Stage

The Concept stage explores the need for a system and defines what problem should be solved.

This stage focuses on understanding the operational context, stakeholder needs, mission objectives, opportunities, constraints, risks, and possible solution approaches.

Typical Objectives

The Concept stage aims to:

• Identify the problem, need, or opportunity
• Understand stakeholder expectations
• Define the system of interest
• Explore operational scenarios
• Identify constraints and assumptions
• Analyze feasibility
• Compare alternative concepts
• Establish an initial business or mission case
• Identify major risks
• Define initial validation criteria

Typical Activities

Activities may include:

• Business or mission analysis
• Stakeholder identification
• Needs analysis
• Operational concept development
• Use case or mission thread development
• Feasibility studies
• Trade studies
• Technology assessment
• Cost and schedule estimation
• Risk identification
• Initial life-cycle planning

Typical Work Products

Outputs may include:

• Problem statement
• Business case or mission case
• Stakeholder needs
• Concept of operations
• Operational scenarios
• Initial system context
• Initial system boundary
• Candidate solution concepts
• Feasibility analysis
• Initial risk register
• Initial life-cycle strategy

Systems Engineering Focus

The Systems Engineering focus is to ensure that the right problem is being addressed before committing to a solution.

The Concept stage should avoid premature design decisions. It should preserve enough solution space to support meaningful alternatives and trade-offs.

Development Stage

The Development stage transforms the selected concept into a defined, designed, integrated, verified, and validated system solution.

This stage often includes requirements definition, architecture development, detailed design, implementation, integration, verification, and preparation for transition.

Typical Objectives

The Development stage aims to:

• Define stakeholder and system requirements
• Develop the system architecture
• Allocate requirements to system elements
• Define and control interfaces
• Design and implement system elements
• Integrate system elements
• Verify requirements
• Validate stakeholder needs
• Prepare for production or deployment
• Reduce technical risk

Typical Activities

Activities may include:

• Requirements engineering
• Architecture definition
• Functional analysis
• Logical and physical decomposition
• Interface definition
• Trade-off analysis
• Modeling and simulation
• Design definition
• Implementation
• Integration planning
• Verification planning
• Validation planning
• Prototype development
• Risk reduction
• Configuration management

Typical Work Products

Outputs may include:

• Stakeholder requirements
• System requirements
• Architecture descriptions
• Interface control documents
• Design descriptions
• Models and simulations
• Verification plans
• Validation plans
• Integrated prototypes
• Test results
• Updated risk register
• Production readiness evidence
• Operational readiness evidence

Systems Engineering Focus

The Systems Engineering focus is to maintain traceability from stakeholder needs to requirements, architecture, design, implementation, verification, and validation evidence.

Development should not be viewed as only design. It includes the technical work needed to prove that the system can satisfy its intended purpose.

Production Stage

The Production stage creates, manufactures, builds, constructs, assembles, packages, deploys, or replicates the system.

For software-intensive systems, this may include release engineering, deployment pipelines, build automation, packaging, and environment preparation.

Typical Objectives

The Production stage aims to:

• Produce the system in the required quantity and quality
• Establish repeatable production processes
• Control configuration
• Manage suppliers
• Verify produced units or releases
• Prepare for delivery or deployment
• Achieve production readiness and quality objectives

Typical Activities

Activities may include:

• Manufacturing planning
• Production engineering
• Tooling development
• Supplier qualification
• Quality assurance
• Acceptance testing
• Release management
• Packaging
• Deployment preparation
• Production configuration control
• Manufacturing process verification
• Factory or site acceptance testing

Typical Work Products

Outputs may include:

• Produced system units
• Software releases
• Manufacturing plans
• Production procedures
• Quality records
• Acceptance test results
• Configuration records
• Supplier evidence
• Deployment packages
• Installation instructions

Systems Engineering Focus

The Systems Engineering focus is to ensure that the system can be produced consistently and that production outputs remain consistent with requirements, architecture, design, and configuration baselines.

Production considerations should be addressed early in the life cycle through design for manufacturability, testability, deployability, and quality.

Utilization Stage

The Utilization stage is when the system is used to provide its intended capability, service, or mission outcome.

This is the stage in which the system delivers value to users, operators, customers, or mission owners.

Typical Objectives

The Utilization stage aims to:

• Operate the system in its intended environment
• Deliver required capability or service
• Monitor performance
• Ensure safe and secure operation
• Collect operational feedback
• Manage operational risks
• Support mission or business objectives

Typical Activities

Activities may include:

• System deployment
• Transition to operations
• Operator training
• Mission execution
• Service delivery
• Operational monitoring
• Incident response
• Performance assessment
• User feedback collection
• Operational configuration management
• Cybersecurity monitoring
• Safety monitoring

Typical Work Products

Outputs may include:

• Operational system
• Mission or service results
• Operational data
• Performance reports
• Incident reports
• User feedback
• Operational procedures
• Updated operational risks
• Change requests
• Improvement opportunities

Systems Engineering Focus

The Systems Engineering focus is to evaluate whether the system continues to meet stakeholder needs in the real operational environment.

Operational use may reveal needs, constraints, interfaces, and emergent behaviors that were not fully visible during development.

Support Stage

The Support stage sustains the system so it can continue delivering value during utilization.

Support may include maintenance, logistics, training, help desk services, spare parts, upgrades, repairs, cybersecurity patching, reliability improvement, and sustaining engineering.

Typical Objectives

The Support stage aims to:

• Maintain system availability
• Restore failed capability
• Preserve safety and security
• Manage configuration changes
• Support users and operators
• Provide logistics and maintenance
• Extend useful life where appropriate
• Improve performance based on operational feedback

Typical Activities

Activities may include:

• Preventive maintenance
• Corrective maintenance
• Reliability analysis
• Spare parts management
• Field service
• Software patching
• Cybersecurity updates
• Training updates
• Technical support
• Obsolescence management
• Configuration management
• Failure analysis
• Root cause analysis
• Upgrade planning

Typical Work Products

Outputs may include:

• Maintenance records
• Support procedures
• Spare parts plans
• Training materials
• Service reports
• Reliability data
• Upgrade packages
• Patch releases
• Configuration updates
• Obsolescence plans
• Support performance metrics

Systems Engineering Focus

The Systems Engineering focus is to ensure the system remains effective, safe, secure, maintainable, and supportable over time.

Support is often where many life-cycle costs are realized. Early design decisions strongly influence support cost and effectiveness.

Retirement Stage

The Retirement stage removes the system from operational use and handles disposal, replacement, migration, archiving, recycling, or decommissioning.

Retirement should be planned before the end of the system's useful life.

Typical Objectives

The Retirement stage aims to:

• Remove the system safely from service
• Preserve required data and records
• Transition users to replacement systems
• Dispose of materials responsibly
• Decommission facilities or infrastructure
• Terminate support obligations
• Manage environmental, legal, safety, and security concerns

Typical Activities

Activities may include:

• Retirement planning
• Decommissioning
• Data migration
• Data archival
• User transition
• Disposal
• Recycling
• Hazardous material handling
• Contract closure
• Configuration closure
• Security sanitization
• Lessons learned capture

Typical Work Products

Outputs may include:

• Retirement plan
• Decommissioning records
• Disposal records
• Data archive
• Migration records
• Environmental compliance evidence
• Final configuration status
• Lessons learned
• Closure report

Systems Engineering Focus

The Systems Engineering focus is to ensure that retirement is safe, responsible, compliant, and coordinated with stakeholder needs.

Retirement may also generate needs for a replacement system, beginning a new life cycle.

Other Life-Cycle Stage Models

Different organizations and domains use different names and structures for life-cycle stages.

The generic life-cycle stages are useful because they are broadly applicable, but they may be tailored or replaced by domain-specific models.

NASA Life-Cycle Phases

NASA uses a project life-cycle model that is tailored for space flight and mission systems.

A typical NASA project life cycle includes phases such as:

This model is more specific than the generic life-cycle model and reflects NASA's mission review structure, technical maturity expectations, and operational context.

Mapping Generic Stages to NASA-Style Phases

A rough mapping may look like this:

This mapping is approximate. Each organization should use its own governing process definitions.

Other Domain-Specific Examples

Other domains may use different stage names.

Examples include:

Software and Digital Services

Software-intensive systems may use stages such as:

• Discovery
• Alpha
• Beta
• Release
• Operations
• Continuous improvement
• Decommissioning

Product Development

Commercial product development may use stages such as:

• Ideation
• Feasibility
• Design
• Industrialization
• Launch
• Growth
• Sustainment
• End-of-life

Construction and Infrastructure

Infrastructure systems may use stages such as:

• Planning
• Design
• Procurement
• Construction
• Commissioning
• Operation
• Maintenance
• Decommissioning

Defense Acquisition

Defense systems may use acquisition phases that include:

• Materiel solution analysis
• Technology maturation
• Engineering and manufacturing development
• Production and deployment
• Operations and support
• Disposal

Key Takeaway

The generic life-cycle stages provide a common structure, but they should be tailored. The purpose is not to force every system into the same process, but to ensure that all important life-cycle concerns are considered.