Downtime

The time an item of equipment is out of service, sometimes as a result of equipment failure. The time that an item of equipment is available but not used is generally not included in the calculation of downtime. Downtime is the time that the asset is not in a condition to perform its required function, including active maintenance time and delays due to awaiting spares, labor, facilities, movement, etc. Unless otherwise stated, downtime due to failure is considered to commence at the instant the item is deemed to have failed and to persist until the equipment is again available.