Aircraft fleet planning is a critical task for airlines aimed at ensuring safety and profitability. Scientific and methodological research in the field of aircraft technical operation efficiency management conducted by leading scientists of the Gromov Flight Research Institute, the State Research Institute of Civil Aviation, and the Moscow State Technical University of Civil Aviation, such as N.N. Smirnov, A.A. Itskovich, Yu.M. Chinyuchin, S.V. Daletsky, G.N. Gipich, I.G. Kirpichev, S.V. Kuznetsov, V.S. Shapkin, and others, have established objective requirements for expected operating conditions that determine the quantitative parameters and design conditions in accordance with which the operational and technical characteristics of aircraft must be specified, evaluated, and confirmed. Significant scientific and practical experience in the field of ensuring and maintaining airworthiness has been accumulated [1–13].

In the context of intensive development and ever-increasing competition in the global air transportation market, improving aircraft operational efficiency is a key factor in the economic sustainability of airlines. One of the challenges in this area is optimizing the aircraft stand-to-flight operating cycle, which directly determines critical metrics such as the annual flight time of the aircraft fleet, its serviceability level, and, ultimately, the profitability of operations.

During aircraft development and operation, a unified scientific and methodological framework is maintained for assessing, confirming, and comparing these metrics. At the same time, there is an objective need to continually improve the scientific and methodological framework for aircraft technical operation, aimed at increasing maintenance efficiency and reducing labor and material costs for airlines.

In practice, aircraft operation management often encounters a contradiction between regulatory targets and operational constraints imposed by ground handling schedules, the actual technical condition of the fleet, and flight duration. The lack of a clear quantitative tool for analyzing the interplay of these factors leads to suboptimal decisions, failure to meet planned targets, or unreasonably high resource requirements.

The objective of this study is to develop a methodology for quantitatively analyzing the aircraft operating cycle aimed at ensuring planned annual flight hours by establishing a quantitative relationship between key operational parameters (annual flight hours, flight duration, ground parking duration, and serviceability factor). This methodology also aims to create a practical tool for standardizing grounding time during the design of new aircraft, determining the minimum required fleet availability for flight plan execution, and identifying time slack and bottlenecks in airline operations.

The scientific novelty of this study lies in the development of an analytical framework for the theory of technical operation as applied to the problem of synchronizing the planned, technological, and actual operating modes of aircraft.

The research material comprised the following: regulatory and technical documentation (OST 1.02785‑2009), the works of leading scientists in the field of technical operation, and technological regulations1.

This article presents a multi-level approach using a set of calculation and analytical methods characteristic of scientific and methodological research in the field of aircraft technical operation.

Based on the analytical and calculation method, quantitative dependencies were derived, determining a quantitative assessment of operating parameters (ground parking duration, number of cycles) for given basic standard operating parameters (annual flight time, flight duration).

The comparative-analytical method compared calculated values with regulatory requirements and actual data, which helped identify time reserves and critical conditions for flight plan execution.

The use of a graphical-analytical method allowed for the visualization of dependencies, making the analysis clearer and the interpretation of complex relationships more accessible for decision-making based on visual data.

Using the limit values and constraints method, critical parameter boundaries (at which the system failed to meet requirements) were identified and the system’s resilience to deviations from the standard state was assessed.

The empirical-statistical method validated the calculation model in practice by comparing calculations with actual data to confirm their reliability.

The used methods made it possible to achieve the research goal of establishing relationships between parameters and creating a tool for improving aircraft operational efficiency.

Estimated values of the key quantitative parameters of expected aircraft operating conditions, including the flight endurance according to a typical profile, the estimated annual flight time of the aircraft, and the duration of transit maintenance (aircraft preparation for a return flight), serve as the initial data for the design of new aircraft [2–5][14].

The flight endurance of an aircraft according to a typical profile tfl is determined based on a feasibility study of the aircraft characteristics (flight speed, aircraft weight), airport characteristics (requirements for the runway or landing site and its equipment), the purpose and regions of aircraft operation (average route length, availability of alternate airfields along the routes, planned aircraft usage characteristics)1.

In this case, the estimated annual flight time for one aircraft Tann, ensured by the maintenance system, is established depending on the flight duration according to the typical profile tfl (tab. 1) [2][14] and in accordance with OST 1.02785-20092.

(2)

(4)

(4´)

(7)

The conducted study demonstrates a sophisticated level of integration of operational and technological parameters in the aircraft maintenance system. The presented methodology goes beyond a formal description of the relationships and provides a practical tool for analyzing management tradeoffs in airline planning.

The fundamental physical relationship under consideration (4) represents a theoretical model of the general dependence of the planned annual flight time on the operational cycle parameters and aircraft serviceability The aircraft flight time is the dependent variable, and its value is limited by preparation time and serviceability. This formula is widely known among leading specialists in the field of technical maintenance; it explains the basic principles of calculating technically feasible annual flight time and is used as a basis for creating management standards, strategic planning, and for analyzing the performance of airlines. It should be noted that in this formula (4) the operating cycle parameters are averaged based on empirical data on aircraft operation and are of a statistical nature [13][15].

The maintenance system management is carried out in a “top‑down” manner, based on averaged aircraft operational data, with the question being posed: “What level of resources is required to achieve the result?” That is, a search is conducted for the optimal balance among interrelated parameters in order to maximize flight hours (a statistical management approach).

The methodology presented by the authors is deterministic in nature and is based on engineering principles, where achieving the planned flight hours is considered a function of the specified operational cycle parameters. The proposed methodology, based on the basic formula (4), establishes the inverse relationships

  This decomposition of the system into elements is based on the physical and technological limitations of the aircraft (flight time, preparation time, and specified flight hours), with flight hours being considered an independent, specified variable. The proposed methodology offers a mechanism for achieving these target indicators. It transforms the standard indicator from a static control plane to a dynamic operational management plane, answering the key question: “By what means and under what conditions can the specified flight time be achieved?” (an engineering-deterministic approach). The developed mathematical model can be used for two-way management of the maintenance system: both “top-down” (from planned indicators to operational tasks) and “bottom-up” (through monitoring the achievement of planned flight time, i.e., from monitoring execution to adjusting the plan).

A system of equations (5), (6), (7), (8) based on academic formulas (1), (2), (3), (4) forms an analytical basis for informed decision-making. It allows:

Despite its practical value, the proposed methodology has a number of limitations that limit its future development:

Despite some simplifications, the proposed methodology not only allows for the calculation of specific numerical parameters for new aircraft, resource assessment, and operational planning, answering the question: “How can operational management be organized to ensure the aircraft achieves the required flight time?” but also for diagnosing problems, assessing risks, and substantiating requirements for newly developed aircraft and ground operations.

This article is an excerpt from a scientific and methodological study devoted to key aspects of aircraft maintenance efficiency management. The work is applied in nature and draws on existing regulatory frameworks and the works of leading scientists in the field of aircraft maintenance.

According to the authors, the study achieved its objective and allowed the development of a methodology for quantitative analysis of the aircraft operating cycle aimed at ensuring planned annual flight hours. The following key conclusions were formulated based on the results of the study:

The presented methodology can serve as a practical tool for aligning an airline’s strategic goals with its operational capabilities, enabling quantitative justification of management decisions, identifying bottlenecks, and assessing risks. Despite its limitations, the model provides a reliable analytical foundation for the further development of decision support systems, improving service regularity, and enhancing the economic sustainability of airlines in an increasingly competitive environment. A formalized, deterministic framework is proposed to complement traditional statistical methods in aircraft performance management.

1. STO ISM TG 4.1.2.1.03.05‑19. (2019). Technological Schedules for Ground Handling of Aircraft at JSC International Airport Irkutsk. Introduced 2019‑10‑24. Irkutsk: JSC International Airport Irkutsk, 579 p. (in Russian) 2. OST 1.02785‑2009. (2010). Aviation Standard. Civil Aviation Aircraft. Operational and Technical Characteristics. General Requirements. Introduced 2010‑07‑01. Moscow: FSUE “NIISU”, 29 p. (in Russian) 3. STO ISM TG 4.1.2.1.03.05‑19. (2019). Technological Schedules for Ground Handling of Aircraft at JSC International Airport Irkutsk. Introduced 2019‑10‑24. Irkutsk: JSC International Airport Irkutsk, 579 p. (in Russian) 4. Там же.