1. Main problem-solving methods and tools in the FRACAS approach

1.1 Preamble

The approaches that have led to the various FRACAS methods for ensuring and improving reliability have a common foundation valid in all sectors of activity: that of problem solving. A problem is the appearance of a situation that is unexpected or prevents the achievement of objectives. A problem is the measure of the gap between a situation described as ideal, on the one hand, and the current situation, perceived as unsatisfactory, on the other. In the broadest sense, this gap, if considered unacceptable, is called a "failure", or a "defect", depending on the sector concerned. Solving the problem means eliminating the deviation (in the best case), or at least reducing it significantly. This situation is encountered in industrial plants, information technology, operations,...