Fleet Availability is a key performance indicator (KPI) in mining operations that measures the proportion of time that a piece of mobile equipment or an entire fleet is in a mechanically operable condition and ready for use, expressed as a percentage of total scheduled time. It is a direct measure of equipment reliability and the effectiveness of the maintenance program, and it serves as a foundational metric for calculating overall equipment effectiveness (OEE) in open-pit and underground mining operations across bauxite, gold, iron ore, and diamond mines.
Fleet Availability is mathematically defined as: Availability (%) = [(Scheduled Hours − Downtime Hours) / Scheduled Hours] × 100. Downtime includes all time the equipment is unavailable due to planned maintenance (scheduled servicing, major overhauls), unplanned maintenance (breakdowns, component failures), and delays attributable to maintenance-related activities. It does not typically include time the equipment is on standby due to operational or scheduling reasons, which is captured separately as a utilization metric.
High fleet availability is critical to achieving planned production targets and reducing the unit cost of material mined. In large iron ore operations, for example, haul truck availability targets of 85–90% are common, while shovel and drill availability targets may differ based on equipment type and age. Achieving high availability requires a robust preventive maintenance program, adequate spare parts inventory, skilled maintenance personnel, and real-time condition monitoring to detect and address potential failures before they cause unplanned downtime. Fleet management systems and telematics play an increasingly important role in monitoring individual equipment availability and driving data-based maintenance decisions that improve overall fleet health and performance.