Spiral model:

As in waterfall model requirement changes are not allowed they went for a new model called Spiral Model.

When do we choose Spiral Model?

  • We go for spiral model whenever modules are dependent on each other.
  • In spiral model we are going to develop and test module by module and hand it over to the customer so that changes can be easily handled.


  • For example consider a product which is having three modules Module A, Module B and Module C
  • First we are going to collect the requirements of Module A, design of Module A, Coding for Module A and  test Module A.
  • Finally Module A is handed over to the customer.
  • Similarly we are going to collect the requirements , Design, coding and testing for Module B.
  • In the testing process we are going to test first module B, then Integration of modules A and B (A+B).
  • The same process continues for all modules.

Spiral model also called as Iterative Model.


  • In case of minor changes we are going to implement the new requirements and changes in the same cycle. we don’t go for an extra cycle.
  • In case of major changes we go for an extra cycle as the changes may effect the existing features.


  1. Flexible for changes.
  2. Customer can use the product at an early stage.
  3. It is easy to develop and easy to test since it is developed module by module.


  1. No requirements review ie., no one are going to cross check the requirements that are taken by the BA or PA.
  2. No parallel deliverables ie, No two steps will be working at the same time.

Q) When we go for Spiral Model?

Ans: When ever modules are dependent on each other then we go for Spiral model.