According to the PMBOK® Guide, specifically within the Perform Integrated Change Control process, any event that impacts the project baselines (Scope, Schedule, or Cost) must be managed through a formal process to ensure the project remains aligned with stakeholder expectations and organizational goals.
Impact on Baselines: The introduction of a critical defect and the subsequent delay in product delivery constitute a significant variance from the Schedule Baseline. In professional project management, you cannot unilaterally change a baseline without formal authorization.
The Role of Change Control: Even though the defect resulted from an already approved change, the " fix " itself is a new action that consumes time and potentially budget. The project manager must document this impact and submit a Change Request for defect repair.
Stakeholder Transparency: Utilizing the change control process ensures that the Sponsor and Customer are aware of the delay. It allows the Change Control Board (CCB) to evaluate the trade-offs: Is the delivery date more critical than the defect? Should the project be delayed, or should the defect be managed as a " known issue " for a later release?
Data-Driven Decision Making: This approach prevents " Gold Plating " or unauthorized schedule slippage. It ensures that the impact is analyzed, recorded in the Change Log, and that the Project Management Plan is updated to reflect the new reality.
Comparison with other options:
B. Crash the schedule to fix the defect: Crashing (adding resources) is a schedule compression technique that typically increases Cost. This should only be done after the change control process has evaluated the options and authorized the additional spend.
C. Leave the defect in and work around it: Since the defect is described as critical, ignoring it would likely violate the Quality Management Plan and result in a failure to meet acceptance criteria during Validate Scope.
D. Fast-track the remaining development: Fast-tracking (performing tasks in parallel) increases Risk. Like crashing, this is a tactical response that should only be implemented after the impact of the defect has been formally processed and the strategy has been approved.
