Delay Analysis Methods
Impacted As-Planned
Impacted As-Planned (IAP) inserts a delay-event fragnet directly into the original, unprogressed baseline schedule and recalculates -- simpler than Time Impact Analysis, but criticized for ignoring how the project actually progressed before the event.
Definition
IAP is a prospective, model-based technique that starts from the project's original baseline -- not an updated schedule reflecting real progress -- and inserts the disputed delay event's fragnet directly into that unprogressed network before recalculating. It's cheaper and simpler to perform than Time Impact Analysis, since it needs only the baseline, but it's criticized precisely for that simplicity: it can't reflect any legitimate resequencing, logic changes, or acceleration that actually happened on the project before the disputed event occurred, which can make its result diverge meaningfully from what a contemporaneous-update-based analysis would show for the same event.
Example
The same 20-day fragnet, inserted into a pristine, never-progressed baseline network with zero float on its chain, produces a straight 20-day extension -- while inserting the identical fragnet into the real, progressed schedule as it stood right before the event might show only 12 additional days, since some schedule gains had already legitimately banked by that point.