Using the priority system to define reactive vs. proactive maintenance

March 8, 2021
Doc Palmer says forget using work-type categories, and consider using a priority system that captures reaction time.

We all know what reactive maintenance is in our hearts, but we seem to have some options for defining it. Some are easier than others. I prefer a simple approach using the priority system. Why do we care what reactive maintenance is? In a planning and scheduling context, we want to do more proactive work to head off reactive work. Thus, we’ll have a more reliable, profitable plant.

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Generally, reactive maintenance is bad maintenance or not even maintenance at all. As John Day points out in his paper (“Maintenance Vision: Total Proactive Maintenance,” from the 1993 SMRP conference), the dictionary defines “maintenance” as keeping in proper condition. If something breaks and we fix it, we actually are guilty of not having maintained it. It broke!

Well, how do we keep something from breaking? We have to work on it before it breaks so it never breaks in the first place; that is, we need to do proactive (good) maintenance. Nevertheless, many plants have become very efficient and organized almost entirely around fixing things as soon as they break. Furthermore, many of these reactive plants have good, profitable operating records. But we don’t want to stop at being good. We want to be great plants, the best we can be, and even more profitable.

Some plants use work type codes to define reactive maintenance such as:

  • PM: Preventive maintenance is routine servicing or low tech inspections.
  • PM-CM: Corrective maintenance is work that came out from a PM task or inspection.
  • PdM: Predictive maintenance is doing the high tech inspection.
  • PdM-CM: Corrective maintenance is work that came from a PdM recommendation.
  • Proj: Project work is work to improve an asset. (In one sense, this work is not maintenance, but for this discussion, we will consider it among the group.)
  • RM: Reactive maintenance is everything else.

But sometimes we find little opportunities of work without looking for them. We want someone to point out a little leak that is not bothering anyone today, but could lead to a bigger problem later, say rotting the deck boards. Yes, you could say the pipe failed to prevent any leaks and now we are in a reactive situation of bad maintenance.

But practically, I think stopping the little leak is proactive, good maintenance, whereas later replacing the rotted boards when they might fail at any moment and hurt someone is reactive, bad maintenance. With this in mind, let’s add CM to the above work type list and redefine RM:

  • CM: Corrective maintenance is other maintenance where it is in time to head off a larger problem.
  • RM: Reactive maintenance is other maintenance where it is too late to head off a larger problem.

Even so in practice, it is somewhat difficult to use work types to define reactive maintenance. For one thing, it is hard to distinguish CM from RM. For example, we could say that replacing a whole bunch of expensive rotted boards in time was CM because at least we did it before someone fell through the deck. Furthermore, some practitioners feel that, if the deck was deemed Run-to-Failure in a past RCM strategy, then whenever the deck does fail, any subsequent maintenance is proactive whether the repair can wait or not. In addition, consider a PM inspection, which finds something (PM-CM) that is so dangerous it has to be fixed now without waiting another minute. Wouldn’t the fix be reactive even though we found it before it hurts someone? It can’t wait. It is reactive.

Instead of work types, consider simply using the priority system to define reactive maintenance:

0: Emergency - Start immediately REACTIVE
1: Urgent - Finish this week REACTIVE
2: Routine High - Finish within 2 weeks PROACTIVE
3: Routine Normal - Finish within 1 month PROACTIVE
4: Routine Low - Finish longer than within 1 month PROACTIVE

Reactive maintenance would be for anything that, when requested, cannot wait until next week. It surprises us. We have to react and disturb our normal preparation efforts. We have less time to get the proper information including parts and tools ready. There is more rushing, which can be inherently unsafe. Even if a PM or PdM route inspection finds a need for emergency or urgent follow-up maintenance, we have to react quickly. So PM-CM and PdM-CM could be reactive or proactive.

The priority system is simple to use because it inherently incorporates “reaction” time allowed. It’s easy and practical to say priority 0 and 1 work orders are reactive, and priority 2, 3, and 4 work orders are proactive.

Let’s go further in applying the simple and practical concept that 0s and 1s are reactive. Let’s consider them as “defects” that affect our reliability and safety. In Six Sigma terminology, a plant experiencing 600 such defects per month seeks how to reduce them. With planning and scheduling, we can improve our productivity to do more 2s, 3s, and 4s to head off the 0s and 1s. With planning and scheduling, we can improve the quality of our work to reduce the later incidence of 0s and 1s.

Another use of 0s and 1s is to consider them as “failures,” according to Larry Bradley, technical superintendent of St. John’s River Power Park. They are failures to our maintenance program to keep them from happening. In MTBF (mean time between failure) terminology, a plant experiencing 600 such failures per month has a MTBF of 1.2 hours (30 days × 24 / 600 failures). Planning and scheduling can improve productivity and quality to reduce failures to increase our MTBF.

Don’t get lost in analysis. Consider simply using the priority system to define reactive versus proactive maintenance. Work on reducing the reactive maintenance by doing more and better proactive maintenance. Use planning and scheduling to help. We want to be great plants where things don’t break, the best we can be, and very profitable.

About the Author: Doc Palmer
About the Author

Doc Palmer | PE, MBA, CMRP

Doc Palmer, PE, MBA, CMRP is the author of McGraw-Hill’s Maintenance Planning and Scheduling Handbook and as managing partner of Richard Palmer and Associates helps companies worldwide with planning and scheduling success. For more information including online help and currently scheduled public workshops, visit or email Doc at [email protected]. Also visit and subscribe to

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