Planned maintenance is work scheduled in advance; unplanned maintenance is reactive work after unexpected failure, and the ratio signals asset health.
Planned maintenance is work that is scheduled before it is needed - inspections, routine servicing, and part replacements booked for a chosen time with parts and people arranged in advance. Unplanned maintenance is reactive work triggered by an unexpected failure, where the breakdown dictates the timing, the urgency, and usually the cost. The split between the two is one of the clearest signals of how healthy an asset base really is.
What counts as planned
Planned maintenance covers anything on a calendar or trigger you chose: time-based preventive maintenance (service the van every six months), usage-based intervals (rebuild the pump every 2,000 running hours), statutory and safety inspections - kit such as respirators lives or dies by its inspection schedule - and condition-triggered work flagged by predictive maintenance before failure. Note the trap in the terminology: planned work can still be a repair. Replacing a worn part you spotted during an inspection is planned corrective maintenance - you found the fault on your terms and fixed it on your schedule.
What counts as unplanned
Unplanned maintenance starts with a surprise: the compressor will not start, the lift throws a fault code, the drill smokes mid-job. Common causes are the predictable ones - skipped services, components run past their expected life, operating equipment outside its rating, and “known issues” that were reported but never actioned. That last category deserves attention, because it is the most fixable: a fault someone noticed three weeks before the breakdown was a planned job waiting to be scheduled.
Why the cost gap exists
The same physical task costs more unplanned because the failure sets the terms. Production or billable work stops while you wait. Emergency call-outs and out-of-hours labour carry premiums. Parts ship expedited because nothing was on the shelf - which is why spare parts management and the planned ratio rise and fall together. And failures cascade: a bearing that would have been a cheap planned swap can destroy the shaft it sits on. None of this needs a statistic to be believed by anyone who has paid a weekend call-out fee.
Measuring the ratio
Planned maintenance percentage = planned maintenance hours ÷ total maintenance hours × 100. A team that logged 30 planned hours and 10 unplanned hours last month is at 75% planned. The point of the metric is the trend, not a borrowed benchmark: if the reactive share is growing, the asset base is ageing faster than the maintenance programme, and the breakdowns are choosing your schedule for you.
Shifting the ratio toward planned
The shift is procedural, not heroic. Put every asset’s service interval in writing and on a calendar. Make fault reporting effortless, so “it’s making a noise” becomes a scheduled job instead of next month’s breakdown. Stock the parts whose absence turns short stops into long ones. And keep history per asset - the machine that generates the most reactive tickets is your next candidate for a tighter schedule or retirement. In AMPthilly, issue reports are raised against the asset with categories such as “needs maintenance”, and every ticket stays on that asset’s history permanently, so the repeat offenders are easy to spot.
Related terms
- Preventive Maintenance - the time- and usage-based core of a planned programme
- Corrective Maintenance - repair work, which can be planned or unplanned
- Predictive Maintenance - condition data used to plan work just before failure
- Equipment Servicing - the routine care that keeps work on the planned side
- Spare Parts Management - the stock discipline that makes planned work possible