Critical Path Analysis
The path driving completion — and why P6 may report the wrong one.
What it is
The longest chain of dependent activities driving the completion date. In P6, “critical” defaults to total float at or below zero (or a set threshold), which is not always the same as the true longest path.
Why it matters
Time entitlement follows the critical path. The path P6 shows depends on your settings, calendars and constraints — so it has to be validated, not assumed.
In practice
- Know your definition: Total Float vs Longest Path. They can return different paths.
- The Longest Path option follows driving relationships to the finish and ignores float thresholds — often the more honest view.
- Multiple calendars distort total float; check the path still makes sense across calendar boundaries.
- A single hard constraint can manufacture or mask criticality.
Watch for
- Trusting “critical = red” without asking why an activity is on the path.
- A critical path running through a constraint rather than logic.
- Near-critical (low-float) paths that quietly take over at the next update.