Clearly, the means of production must provide a suitable level of service. This level of service can be characterized by a number of indicators. We often use the terms reliability, availability, commitment rate, efficiency...
These concepts, although complementary, have different meanings, and we'll focus here on availability and how to assess it, first in forecasting, then in operation.
The concept of availability is directly related to that of reliability and maintainability. The characterization and quantification of the latter two require probabilistic calculation methods. Consequently, availability calculations also frequently call on probabilistic methods.
The topics covered in this article are illustrated with examples that illustrate some of the principles of availability calculation in different situations. While they may be considered sufficient in some cases, it would be incorrect to consider them as representing the full range of methods that can be used to tackle more complex problems.