This paper notes that the success of a quality management system depends on how effective and efficient the processes carried out under the control of this system will be. In accordance with the requirements of the ISO 9001:2015 standard, one of the main principles of the functioning of a quality management system is the application of a process approach. To date, the process approach is the most progressive; therefore, it is widely used in various fields of activity. It allows you to determine the cause and effect relationships of the occurrence of problems, as well as determine where and when the problem arose and what is the root cause of its occurrence. The choice of performance indicators and criteria for evaluating the effectiveness of the processes of the quality management system is the most important step in conducting this work since the results obtained should provide the top management of the enterprise with the most adequate data on the state of functioning of the controlled processes and outline possible ways to improve both the system itself and quality. values created because of each given process. A methodology for analyzing the effectiveness of processes is considered, starting with the definition of the context (business environment) in which the controlled process should be carried out. Having established the external and internal context that can affect the particular process being controlled, it is necessary to identify a set of stakeholder needs from which the risk and opportunity components for performing each process under consideration can be derived. To analyze risks and opportunities, it is proposed to apply a methodology for analyzing the types and consequences of potential defects, known as the FMEA method. Controlled indicators of the process and criteria for their effectiveness are selected based on the most rated needs of stakeholders. In the case when certain indicators of the effectiveness of the process do not satisfy the top management of the enterprise, a search is made for the reasons for the low level of the indicators of effectiveness. The goal is to determine the root cause of the nonconformity to organize work to eliminate it. The analysis is proposed to be carried out using Excel tables. An example of determining the root cause of the inconsistency of the “Aircraft Engine Design” process is given.