I believe that the key to project success is in managing the expectations of your customer.

From project initiation to closing the PM must struggle to keep the expectations of all project stakeholders grounded in reality.

All of us have requests made of project team that are entirely unrealistic (unstructured requirements and unrealistic dates being the most common). These issues are ‘project killers’ and must be addressed. As soon as the unrealistic demand is placed on the project the PM is responsible for communicating this to the customer and all stakeholders.

I can feel at this point the question “But what if the customer refuses to accept the PM’s explanation of the problem and continues to believe that the impossible is doable?”

This is where your project change control and communications plan kicks in. The PM must do an assessment of the risk (which is what unrealistic expectations are) and communicate it to all the project stakeholders.

At this point, one of the project stakeholders is bound to take this up as an issue that needs to be addressed. If no one objects and everyone sticks their head in the sand then they have accepted the risk.

When the project does not meet expectations due to refusal to address the unrealistic expectations of the customer, the PM should bring out the risk assessment and point to the failure to address the risk as the cause.

This may not help very much politically. But when the PM has properly documented the failure to address the risk, the organization will have an opportunity to learn from the mistake.