The most important factor in preventing aircraft accidents is to take lessons from the accidents that have already occurred. Analyzing aircraft accidents and incidents and finding out what caused the accident is the first step to avoid the next accident. In the analysis of an accident, if the cause is environmental or technical reasons, it will be easy to classify the reason for this accident. For example, engine failure, reduced visibility due to heavy fog, or turbulence can be categorized very easily. However, if the accident comes from a human-caused factor, it would be relatively difficult to classify it. Shappell and Wiegmann first developed a human factor analysis and classification system (HFACS) by examining the accidents that took place in the US Navy for classification of accidents involving human factors. The human factors analysis and classification system is based on Reason's Swiss cheese model. Human factor analysis and classification system emphasizes that not only the cabin crew are the guilty of cause of the accident but also there are many factors behind the accidents that extend up to the managers. This model continues its validity today and is frequently used in the literature. In this study, these models will be explained in detail and then Human factors analysis and classification system will be applied to the most deadly accidents that have taken place in the Turkish air space. Analysıs results will be interpreted and in accordance with the analyzes, a solution proposal will be presented to prevent accidents.