Flight safety risk awareness at flight test activities with analytical hierarchy process method

Abstract

In 1903, the Wright brothers succeeded in flying the first manned and propelled heavier-than-air aircraft, which soon led to the birth of aviation and the spread of aircrafts. Aircrafts, which started to be produced for different purposes, have caused many accidents and even deaths in their post-production use and especially in the design development stages. Over the years, various arrangements have been made, international agreements have been signed, and local and international organizations have been established in order to prevent these accidents and deaths and to manage aircraft operations safely. Annex-19 Safety Management System (SMS), which is the 19th and last annex of the International Civil Aviation Organisation (ICAO) Air Transport rules, is a system for managing the safety risks of organizations carrying out aviation activities and ensuring the effectiveness of safety risk controls, and includes systematic procedures, practices and policies for the management of these risks. Implementation of SMS in organizations carrying out civil aviation activities has started to be made compulsory by relevant local and international authorities. The studies which aim to prove whether the designed and manufactured aircraft provide the desired performance are called flight tests. Advances in technology, when incorporated into aircraft design processes, have led to the creation of formal requirements and specifications that provide universal benchmarks in aircraft design processes. Parallel to these developments, the aims and applications of flight testing have also matured and become a discipline. Flight tests are high-risk flights since they are carried out with aircraft that have not been certified yet, have low flight hours, and have many unknowns about the nature of the aircraft. For these reasons, within the scope of flight test activities, the risks should be determined in advance, necessary mitigation studies should be carried out and test procedures should be determined. It is stated in the Flight Test Operational Manuel (FTOM) guide document published by EASA that flight test organizations should improve the SMS. In this document, flight test risk management activities and risk management activities that must be carried out within the scope of SMS are separated. Flight test risk management was held responsible for the management of specific risks specific to each flight test, while SMS risk management was held responsible for operational risks that constitute continuity. Within the scope of this study, the Analytical Hierarchy Process (AHP) method, which is a hierarchical weighted multi-purpose decision analysis method that combines qualitative and quantitative analysis methods, was used to provide a holistic awareness of flight safety risks in flight test activities. When using the weighting function of the AHP method, the safety risk matrix published by the SMS risk management of the relevant institution is based on and it is aimed to determine how important the risks are to each other. The values selected from the risk matrix for the risk specific to the flight test and operational risks are multiplied with the coefficients to be determined for each risk level to create a comparison matrix and the weight of each risk is calculated. It is expected that the flight test risk will have the largest share in the weighting to be achieved, and the evaluation of the results in this direction. Providing corrective feedback on the coefficients determined for each risk level, the choice of risk value and the structure of the risk matrix are the gains that can be achieved in addition to flight safety risk awareness. The use of the safety risk matrix and the values here while calculating the weights of the risks eliminates the subjective evaluation in the AHP method and makes the consistency index 0. However, the method used is subjective due to the structure of the risk matrix, the selected risk values and coefficients. For this reason, the returns to be obtained in line with the outputs of the method will allow these subjective values to change and take their optimum form over time. This study, which started in line with the definitions in the EASA Part-21 FTOM Guide document, became an example of how Flight Test Risk Management and Safety Management System can work together. As a result, it is aimed to raise awareness of the flight safety risks involved in Flight Test Activities to the relevant flight test team by making use of the weighting feature of the AHP method.