With respect to the time horizon, the maintenance planning process is usually divided into three levels. The first level is called strategic planning. Here, basic strategies for maintenance and renewal planning are defined. The second level is that of tactical planning, where a rough planning of the large maintenance tasks is performed in the medium term. The last level is that of operational planning. At this level, detailed work plans are developed to ensure that all tasks are carried out smoothly. Furthermore, it is necessary to be able to react dynamically to unexpected and unforeseen failures or changes during the execution of the plans.
The three planning levels are closely linked. On the one hand, strategic planning provides the strategies that form the framework for tactical planning, and the rough time planning at the tactical level is the basis for operational planning. On the other hand, the evaluation of the implementation of the operational plans provides new information for the first two planning levels, which should be taken into account.