The paper discusses the issues of flight’s security planning in accordance to factors linked with the matters of air safety. Current role and tasks of the Air Control Service (short form in polish – SBL) in the Polish Armed Forces aviation was presented in accordance to established air-rules in use. The mathematical model of serious accidents’ assessment and the analysis of crash causes process was described in consideration to officially named in aviation nomenclature ‘serious accidents’. The theoretical methods were used in the work: analogy, system analysis, analytical and comparative method. Moreover, the emipric observation method was used. Based on real examples, the causes of catastrophic events were estimated. The types of special situations in flight, constituting an indispensable factor of high risk in the air, have been specified. The discussed issues have been correlated with the tools used at the stage of investigating an air accident. The results of the analysis performed, combined with the synthesis of selected facts and data from the reports of the Flight Safety Services, prove that the basic factor of maintaining an appropriate level of safety in the air is maintaining both appropriate service dates and pre-flight inspections, as well as the need for increased caution in assessing psycho-physical pilot’s conditions during selecting personnel for an aviation task. In military aviation, the pressure factor, the emphasis on completing an aviation task / exercise / combat mission, seems to be an important factor influencing the accident rate. Conclusions: Risk estimation at every stage of the preparation of an aviation task in terms of the human factor and equipment is the key to maintaining an adequate level of flight safety. Possibilities and threats analysis should be preceded by an appropriate expert assessment. In the air, the aim should be to definitely preserve and maintain the safe, not to be successful in the air mission itself. A cardinal mistake made in the process of planning combat missions is sometimes goal-oriented in the category of completing an exercise. A „task-oriented” style in the air, in relation to the human factor, may result in a simply opposite, tragic ending.