In the process of performing a complex of works on refueling of civil aviation aircraft, one of the key issues is to ensure flight safety by controlling the quality of aviation fuel directly during refueling operations. Currently, to ensure the purity of the refueled jet fuel, water separators with filter elements of a normalized degree of purification are installed on the aircraft refueling facilities, the operation of which in the working area provides normalized indicators of cleaning jet fuel from water and mechanical impurities. As practice shows, in the process of refueling aircraft, for various objective and subjective reasons, sometimes there are stochastic situations in which quality indicators go beyond the limits established by regulatory documentation and are not deterministic, and the subsequent state of such a system is described by values that characterize an extremely low level of jet fuel purification with negative consequences for flight safety. This paper presents a mathematical description of the functioning of water separator filters in the working area, where standardized indicators of the quality of aviation fuel are provided during the refueling of aircraft. The article deals with the issue of blocking the refueling of aircraft in the event of the appearance of non-normalized technical documentation indicators of the quality of aviation fuel, which arise due to a number of different factors that lead to negative cause-and-effect relationships for flight safety. Based on the mathematical description, an approach to creating a system for protecting and blocking the refueling process under the working name "Barrier" is proposed. Of the greatest interest for the study are typical water separator filters installed on refueling vehicles as terminal technical devices for fuel purification during refueling of aircraft.

In the process of air transportation, a large amount of information exchange plays an important role in the timely management of aircraft flights. The work of any airline and airport consists of many processes that involve a big number of participants. One of these issues is timely aircraft refueling. The use of the blockchain technology makes it possible to process an airline request for aircraft refueling in a timely manner, make payment and exchange of accounting documents between the airline and the refueling complex. The paper gives the main definitions for the elements of the smart contracts and their interrelationships based on the blockchain technology when performing accounting operations and payment transactions for aircraft refueling. The article is devoted to a comprehensive study of the smart contract technology application in the aircraft refueling system, in particular, the exchange of accounting and payment documentation between the airline, the refueling complexes of civil aviation airports and banks. The aim of the research work is to study the application of the blockchain technology in the aircraft refueling operations. Based on the analysis it is necessary to develop a scheme for the use of the smart contract technology when aircraft refueling, which allows the parties concerned to reduce the volume of accounting and payment operations and increase the operating efficiency of the objects and subjects of the refueling process. The paper presents the chain of information passing and blockchain transformation varying from the execution of refueling operations to the execution of banking operations, payment for jet fuel and related services for aircraft refueling. Special attention is paid to the role and location of aircraft refueling facilities as a key element of the module for automatic reconciliation of accounting and payment documents in the formation of a smart contract. Based on the analysis of the blockchain technology application, a scheme of interaction among an airline, a refueling complex and a bank is proposed. The application of the proposed scheme allows the airline to pay for refueling at the time of refueling without time-consuming accounting operations and prepayment for jet fuel, thereby reducing the accounting time.

In civil aviation primary focus is on the quality of fuel filled in the aircraft fuel tanks, as one of the components of flight safety ensuring. The introduction of digital technologies and trends in automation, digitalization of modern civil aviation aircraft provision are becoming the basic tool for civil aviation refueling complexes in terms of ensuring flight safety of civil aviation aircraft. This article considers the processes of airfield control that take place in the stationary operating conditions of refueling complexes of civil aviation airports as Markov processes and studies the approaches to their mathematical modeling. The authors claim that in the case of disruption, there is a transition from Markov to Poisson processes, which mathematical description requires different approaches. The practical application of these statements is obvious in the study of the states probabilities value as a function of time t. For practical purposes, the limiting probabilities of states at t→∞ are of interest. This creates conditions for entering new variables, such as performance and others. Thus, Markov processes allow us to apply the mathematical apparatus of operations research, where the system of states is transformed into the queuing system. To maintain Markov processes, the authors suggest giving due consideration to the objects and technical means of airfield control functioning including: retrofitting of filling points and refueling facilities with closed sampling systems, operational measurement of aviation fuel quality indicators and registration of their results, automated monitoring of filter elements condition while refueling and its blocking in the case of stochastic differential pressure beyond the specified indicators. A special novelty is the view on the measuring process of the aircraft refueling operations as an integral part of airfield control, using block chain technologies as an advanced application of Markov chains.