Spiral Model:

  • This spiral model had four phases planing, risk analysis, engineering and evaluation.
  • It emphasis more on risk analysis.
  • In this model the project undergoes each phases repeatedly called spirals.
  • The planning phase is the baseline spiral and each subsequent spiral is build on spiral model
  • This type of model is used in risk analyzing for eg: in space crafts.

Advantages :

  • Importance is placed more on risk analysis
  • Software is produced in the early stage.

Disadvantages :

  • Not suitable for small projects
  • It is very costly
  • Needs expertise for such model