What is Spiral Model? Advantages and Disadvantages of Spiral Model

Spiral Model is highly use in IT companies. This model involves strategies, which is combination of incremental and prototype models. This Spiral Model is best to use for large projects which required more management and planning.

Spiral Model

  • The spiral model is a realistic approach to the development of large-scale software products because the software evolves as the process progresses. In addition, the developer and the client better understand and react to risks at each evolutionary level.
  • The model uses prototyping as a risk reduction mechanism and allows for the development of prototypes at any stage of the evolutionary development.
  • It maintains a systematic step wise approach, like the classic Life Cycle model but incorporates it into an iterative framework that more reflect the real world.
  • If employed correctly, this model should reduce risks before they become problematic as consideration of technical risks are considered at all stages.

Spiral Model

Spiral Model’s phases are:

  • Planning phase
  • Risk analysis phase
  • Engineering phase
  • Evaluation phase


In planning phase gathering the requirement and analysis on it. Performed major task like reviewing the requirement, identifying necessary resources and work environment. The deliverables will be a system requirement specification and business requirement specification documents.

Risk analysis

The risk analysis phase focused on the risk and alternate solutions, trying to find out technical as well as management risk. After risk found perform the activities to finalized risk.

Engineering Phase

In this phase basically performed development and testing where actual work product made. The deliverables for the engineering phase will be source code, design documents, test cases, test summary, defect report etc.


Customer’s involvement take placed in this Evaluation phase. Customer evaluates the work product and ensures that product meets all requirements if any changes required to the customer in product, again all phases will be repeated. It is important to get feedback fro the customer before releasing the product.

Advantages of Spiral Development Model

  • Spiral Model mostly concentrates on risk analysis.
  • Most useful for large and risk projects.
  • Spiral Model used if requirement changing frequently.
  • Focused model for all phases.
  • Customer evaluation phase made this model useful.

Disadvantages of Spiral Development Model

  • For risk analysis phase required expert person to make analysis.
  • Not useful for small projects.
  • Project duration and cost could be infinite because of spiral feature.
  • Documentation could be lengthy.

When to use Spiral Model:

When creation of a Prototype is appropriate .When costs and risk evaluation is important. For medium to high risk projects. Long-term project commitment unwise because of potential changes to economic priorities. Users are unsure of their needs. Requirements are complex. New Product line. Significant changes are expected (research and exploration).

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