The meteorological situation is one of the decisive factors determining the safety and frequency of civil aviation flights. Weather hazards (WH), associated with cumulonimbus clouds, such as a heavy shower, thunderstorm, hail, combined with high atmosphere turbulence, quite often lead to aviation events and even accidents. Currently, a domestic weather radar system of the near airfield zone (WR) “Monocle” has been developed and successfully operated. The criteria for the classification of meteorological phenomena (MP), used in the WR, have been developed individually for each phenomenon and have some heuristic character. These criteria are cumbersome and complicate the process of automating the WH classification. In this case, there is a natural desire to generalize the criteria and optimize them in accordance with the theory of distinguishing statistical hypotheses. This article discusses the application of the Bayesian approach to the WH classification. The statistical Bayesian decision theory assumes decision-making in terms of the probability theory when all significant probabilistic values, so-called sufficient statistics, are known. In order to obtain statistical descriptions of the probability distributions of reflectivity and the eddy dissipation rate (EDR), an analysis of radar signals, reflected from such MP as a rain shower, thunderstorm, hail was carried out. The article provides brief descriptions of the methods of conducting experiments to form statistical database and its analysis. Based on the above methods, the statistical parameter H(EDRmax) analysis for a rain shower, the amplitude distribution of reflectivity parameters and the EDR (Zmax, EDRmax) for thunderstorms and hail was carried out, which showed the low distinguishing ability of each individual parameter when solving the problem to classify MP within the assigned alphabet. The obvious solution is dictated by the theory of recognition. To increase the classification confidence, it is essential to share information parameters, for example, in the form of multidimensional distribution densities of the probabilities of random parameters. The article presents a parametric description of the MP “rain shower-thunderstorm-hail”  classification features. An analysis to evaluate the probabilistic characteristics of the WH classification for the adopted empirical classification criteria in the WR shows that the adopted criteria are far from optimal in terms of the probabilities of the correct classification, especially in the rain shower case. It is obvious that a problem solution of the assigned classification confidence is associated with the optimization of the feature space and classification criteria. Based on the data obtained, it is necessary to build an algorithm to classify the WH “rain shower-thunderstorm-hail”.

   The addition of anti-water crystallization fluids (AWCF) in aviation fuels (AF) is a radical and relatively simple method to prevent ice formation in the aircraft fuel systems and aviation engines (AE). The anti-water crystallization fluids use is extremely important for our country. However, failures of fuel systems components due to icing also occur when the anti-water crystallization fluids are added to aviation fuel. The article shows that one of the most significant causes is a decrease in standard concentration of the anti-water crystallization fluids in aviation fuels after refueling due to mixing loaded fuel with the standard-anti-water crystallization fluids content with the remaining fuel in aircraft tanks, both with and without the anti-water crystallization fluids. At the same time, the anti-water crystallization fluids content control in aviation fuels after refueling is not carried out. It is shown that the solution to this problem can be a transition to variable anti-water crystallization fluids metering in aviation fuels, taking into account the remaining fuel in the aircraft tanks and the fuel in the aviation fuel supply technological equipment. Developing metering units with the variable anti-water crystallization fluids supply to aviation fuels is not currently associated with issues. The formula is proposed, and the calculation of the required anti-water crystallization fluids metering is shown to ensure its standard value in aviation fuels after refueling. It is also shown that the required metering varies long-range: from 0.18 to 1.31% vol., and in all the cases, exceeds standard metering of 0,125 ± 0,025% vol. for civil aviation. The improvement of the anti-water crystallization fluids metering procedure in aviation fuel is feasible to ensure the reliability of aircraft fuel systems and aviation engines operation as well as flight safety.

   A significant number of aviation incidents is related to loss of control in flight and controlled flight into terrain (LOC-I, CFIT, LALT categories). Investigation of these aviation incidents has revealed that these incidents often occur due to the need for rapid changes in flight routes as a result of detecting obstacles, such as thunderstorms, along the aircraft's path. During the determination of alternative routes to circumvent the encountered obstacle, as well as during the implementation process of the chosen rerouted route, the flight crew makes errors due to increased psycho-physiological workload and time constraints. This article presents an approach to the automatic rerouting of the aircraft's flight route to avoid obstacles detected during flight. The algorithm proposed by the authors allows for evaluating the safety of the original route, calculating alternative route options to bypass the obstacles encountered during flight, verifying their feasibility considering the aircraft's flight technical characteristics and control parameter limitations, and selecting the optimal rerouted route based on specific criteria, such as minimizing the increase in the flight route length, reducing additional fuel consumption, time required for implementing the new flight route, etc. Examples of rerouting the flight route of a hypothetical aircraft with detected obstacles along the flight path are provided in the article to demonstrate the algorithm's functionality. It is shown, in particular, that in the considered example, the shortest route for obstacle avoidance is not optimal in terms of time. It is also demonstrated that the safety of flying along the identified alternative rerouted routes depends, among other factors, on the selected flight speed. Therefore, for each calculated rerouted route, the algorithm determines a range of speeds within which the implementation of the obtained rerouted route is possible. This highlights the complexity and non-triviality of the pilot's task of autonomously finding a safe obstacle avoidance route on board the aircraft.

   In order to solve the tasks of increasing capacity of the air traffic service sectors (ATS), it is planned to use a number of measures to regulate air traffic flows at the stages of strategic and pre-tactical planning. In practice, the application of such measures is ineffective due to the deviation of the parameters of actual flights from those stated when submitting flight plans.

   The purpose of this study is to identify the main problems in the air traffic planning organization for the subsequent proposal of measures to improve the regulation of air traffic flows and prevent conflict situations at the stages of strategic and pre-tactical planning.

   To achieve this goal, the key documents of air traffic planning were analyzed, the analysis of flight parameters at different stages of planning was conducted on the example of the Moscow Area Center of the Unified Air Traffic Management System (UATMS). The review of the key documents regulating air traffic planning in the Russian Federation and the ICAO recommendations shows difficulties in coordinating and exchanging information between the parties concerned in the Russian Federation airspace management. Deviations from the schedule during the aircraft arrival/departure are calculated using the example of Domodedovo Airport. The number of submitted and canceled applications for the airspace management (ASM) during the air traffic planning in the Moscow Area Center of the UATMS is analyzed. The conducted studies allow us to draw up a conclusion about the state of the air traffic planning system and justify the inexpediency of detecting and preventing conflict situations at the stage of pre-tactical planning. The research revealed the obvious shortcomings of air traffic management in the Russian Federation, which can have a significant negative impact on the safety and economic efficiency of aircraft flights.

   The operational control system (OCS) of civil aircraft (A/C) airborne equipment is an important component of its technical operation system (TOS). Operational control is an integral part of the technical operation process. It makes it possible to assess the technical conditions (TC) of the objects to be monitored in various states of airborne equipment operation, aircraft preparation for flight, various types of maintenance and recovery. The main property of operational control is the reliability of control. The key task of operational control is not only to determine the type of technical condition, but also to quantify the correctness or erroneousness of decision-making. Control reliability characteristics (CRC) are quantitative indicators of the degree of objectivity in decision-making. Depending on the level of task details, it is necessary to distinguish the control reliability characteristics of units, functional systems (FS) and avionics suites for various means of operational control: built-in test equipment (BITE), on-board self-contained, ground-onboard and ground systems. The choice of the control reliability characteristics is based on the system analysis and the mathematical apparatus of logic, probability theory and mathematical statistics. Rational sets of technical states and decision-making about the technical conditions of functional systems and avionics suites are formed. Based on these sets, three groups of control reliability characteristics were identified. The first group consists of conditional probabilities of transitions in the operational control process under various types of control. The second group consists of unconditional probabilities of transitions in the operational control process under various types of control. The third group consists of a posteriori decision-making probability in the operational control process under various types of control. Analytical dependences for calculating the control reliability characteristics of three groups for functional systems and avionics suites and relationships between them are determined. The air-conditioning system was used to calculate the reliability of the control.

   Spline couplings, due to their high reliability and strength parameters, are widespread not only in mechanical engineering. The ability to transmit high torque with a sufficiently long service life has led to the extensive use of these couplings in the aircraft industry. Since this unit is under heavy loads in aircraft gas turbine engines, much attention is paid not only to strength characteristics, but also to the influence on the dynamic parameters of the rotor system. To mitigate the risks of destruction and the occurrence of defects, a large number of studies are carried out allowing us to evaluate the rotor system operation with splines and make a forecast of its behavior in the event of various factors leading to a change in the operation of splines. This paper provides a review of various methods, techniques and models of involute spline couplings used in the analysis of the dynamic behavior of rotor systems. The analytical models that allow us to take into account the coupling in various systems as well as finite element models that demonstrate the description of various processes in splines. The publications, devoted to the comparison of finite element models with analytical ones confirming the results associated with the dynamic characteristics of systems with an increase in radial and angular swashes, have been considered. The results of comparing the above models and their results with experimental research to verify and confirm various effects are also presented. The given research of rotor systems with swash allows for a conclusion about a significant spline influence, since they can cause a change in the coupling rigidity, redistribution of contact, increased loads in meshing, increased vibration amplitudes, change in the spectrum of excited frequencies and self-oscillatory processes due to various factors.