How to reach the required availability in the HL-LHC era

The HL-LHC has ambitious integrated luminosity goals in the region of 250 fb$^{-1}$ per year. This level of performance will required excellent machine availability. After a definition of terms and assumptions, the availability to date is reviewed while noting the importance of accurate and reliable tracking. Other possible areas of improvement and future challenges which could impact the overall availability are then discussed. Estimates based on extrapolation from present experience are given. Injector availability will also be important for the overall LHC performance and the need for sustained, well-planned consolidation is recalled.