Definition
Unplanned downtime is the portion of total downtime attributable to an unexpected failure rather than an agreed schedule: the asset stops without prior planning, forcing a reactive response. It is the specific counterpart to planned downtime within the total downtime figure, and a key input to availability and reliability measures.
Key facts
- Specifically the unexpected-failure portion of total downtime, distinct from planned downtime's agreed, scheduled portion.
- Typically more disruptive than an equal amount of planned downtime, since it forces reactive response and often catches spare parts or labor unprepared.
- Tracking the ratio of unplanned to total downtime is a common indicator of maintenance program maturity.
- Feeds directly into availability calculations and is often the primary target for reduction through improved maintenance strategy.
How is Unplanned downtime calculated?
Unplanned downtime measures the specific portion of total stop time caused by an unexpected failure (an event not covered by an agreed maintenance window or scheduled changeover) forcing a reactive response from maintenance and often production.
What influences Unplanned downtime?
Downtime is the total figure covering all non-productive time. Planned downtime is the portion attributable to an agreed, scheduled reason. Unplanned downtime is the remaining portion caused by unexpected failure: the two together should account for the full downtime figure, and the balance between them is a common health indicator for a maintenance program.
FAQ
Frequently asked questions
Which downtime arises unexpectedly?
Unplanned downtime: the portion of total downtime caused by an unexpected failure rather than an agreed, scheduled reason, forcing a reactive maintenance response.
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