What exactly is an out-of-sequence activity and why do I care?
Quick Answer: an out-of-sequence activity is any activity that is in-progress or has completed before one or more of its predecessors.
This condition is reported in the warnings section of the P6 Professional and EPPM Schedule Log.
Take a look at the following example:
Above: a simple schedule with a chain of linked activities.
Let’s see the outcome of entering status to activities that don’t start in the planned sequence. In the following figure you can see that Activity B has completed, but Activity A – its predecessor – has not started yet.
Primavera P6 Professional and P6 EPPM will report this in their schedule logs as an out-of-sequence activity. The ScheduleLog.txt below shows the out-of-sequence activity listed under the warnings: section of the log. More about the schedule log shortly.
What if the predecessor is only in-progress?
An incomplete predecessor will keep the activity on the out-of-sequence list until the offending predecessor is 100% done.
And if the activity itself is only in-progress?
What if it’s Start-to-start with its predecessor?
Yep. If it is in any way listed as a successor to an activity that is not completed – it’s out-of-sequence.
And why do I care?
Oh yes, I didn’t get to that yet did I. Well, it can tell you a few of useful things. The logic could have been incorrect in the first place, some progress was overlooked on the predecessor, or the guys on site are just doing things differently to the original plan. So if you see these warnings, it’s always a good idea to check into both the schedule logic and if necessary what’s going on out in the field.
About the Schedule Log
Accessible from the Schedule dialog: the Primavera P6 Schedule Log is an excellent, powerful and yet sometimes overlooked tool – that for me at least – is a major differentiator between P6 and other scheduling systems. Once I caught on to this log’s existence, I leaned on it more and more for quick checks to my schedule’s integrity. To use it, just be sure that you have the ‘Log to file’ option checked in the Schedule dialog and you’re good to go. You can then click the View Log button at any time to open the latest log. If you’re running the ‘Schedule automatically when a change affects dates’ setting in the scheduling options dialog, the log updates whenever you make a change that affects dates.
It provides some extremely useful information about the state of your schedule. It reports errors, warnings, statistics and more, which will be the subject matter of some future blogs.
Click here to download a sample of the ScheduleLog.txt file that our little example above generated.
Happy ‘in-sequence’ scheduling Peeps.