It is a method to achieve a task or goal when the planned method isn't working. What is it?

Alternative scenarios

Plan-B  

If we faced big problems in line of action and we found that the plan for the management of work has become useless, we  replace it by the Situational plan

It is the result of a planning process to determine the positions of alternative options when we see  conditions were not taken into account.

I BELIEVE IT IS A CONTINGENCY PLAN.OR PLAN B.

Replan or plan B. 

In some case.  change the baseline plan. 

GAP Analysis

Contingency Plan or Plan B.

For more clarification, in the normal work issues if the plan is not working you can shift to plan B, however your planning system studies you have your risk plan in place.

In another way of problems like "Revolutions, strikes .....etc" you should setup a crisis management system in place.

All is under the bussiness planning and risk analysis.