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This work describes the procedure for determining the expected values of UAV radio-heat contrasts () and discusses its angular dependences, as well as the estimation of UAV detection distances at four points cm and mm ranges (12 GHz, 20 GHz, 34 GHz, and 94 GHz). This paper reveals the pronounced frequency dependence on brightness temperature () and of a fiberglass unmanned aerial vehicle (UAV) made from composite fiberglass materials. The quantified experiments are conducted against a sky background under various weather conditions and wave ranges. The qualitative physical interpretation of these properties and their frequency dependence is proposed, reflecting the coefficient values and radio brightness of the background. The weak influence of weather on the observed UAVs in the X and Ku bands are demonstrated along with the multiple decreasing detection characteristics and advantages of the W band under bad weather conditions (the appearance of rain or thick cloud). This work presents data on the values of UAV contrasts, observed against the background of the sky and the regularities noted could be useful for predicting the effectiveness of the proposed radiometric detection and tracking system.

Safety of air transportation strongly depends on the performance of on-board positioning sensors. Positioning by data from navigational aids is considered by international aviation community as one of the main stand-by positioning approaches onboard of civil airplanes. However, only positioning by pair of distance measuring equipment (DME) meets requirements of Performance-Based Navigation. A DME service volume model based on path loss between a pair of transmitting and receiving antennas has been proposed in the paper. The model takes into account the influence of relief on radio waves propagation and diffraction from high-altitude elements of relief. The proposed model has been used in the analysis of DME global network performance. In particular, performance of a global network is analyzed based on availability area of DME service, area of positioning by pairs of DME/DME support, availability of particular positioning accuracy, and areas of meeting various RNAV requirements. Obtained results indicate that only in 27.76% of global airspace a DME service can be provided. However, only within 15.9% of airspace, a DME/DME positioning can be used. Results of the analysis indicate about the necessity of actions for further development of global navigational aids network in order to guarantee safe airlines connections around the globe.

У даний час проблема відмови основної системи позиціонування літального апарату є актуальною внаслідок дії факторів перевідбивання та ненавмисного глушіння радіосигналів під час поширення у просторі. Вибір ефективної системи резервного позиціонування є важливим завданням сучасної системи управління польотом. Резервні системи позиціонування повинні відповідати всім вимогам навігації, що базується на характеристиках, згідно із специфікацією, що використовується у повітряному просторі. Стаття спрямована на аналіз доступних алгоритмів позиціонування та систем для використання на цивільних літаках у разі відмови первинної системи позиціонування. Позиціонування за допомогою навігаційних засобів вважається основною альтернативою у випадку відмови первинної системи для повітряного простору України через достатню мережу наземних станцій. Результати аналізу ефективності у вигляді зон відповідності вимогам специфікацій навігації наведено для повітряного простору України на FL 290. Отримані результати можуть бути корисними припідготовцы пілотів для візуалізації зон, що не підтримують певні навігаційні специфікації, та у процесі модернізації наземної мережі радіонавігаційних засобів України.

In this paper, the potentials of radar polarimetry to estimate wind speed is presented and discussed. The algorithm for wind speed estimate based on Weber numbers is demonstrated. The algorithm is based on the fact that liquid particles under the influence of wind can be bifurcated under the conditions of critical deformation. Using one the connection between backscattering from liquid hydrometeors and drop sizes in reflecting volume the information about the wind that causes the fission of the drops of particular sizes is extracted. The method of drop size evaluation with polarimetric radar is demonstrated and an algorithm for wind speed estimate on the base of Weber criterion, breakup conditions, and hydrometeors discrimination with similar polarization properties was proposed.

Separation minimums create an important part of safe air transportation. Mission performing by Unmanned Aerial Vehicles (UAV) within an urban environment has multiple hazards including collision with a ground, artificial construction, and other airspace users. Separation minimums identify a safety boundary for each flying object to ensure the target level of flight safety in Urban Air Mobility. An approach of separation minimums selection based on performance of UAV on-board positioning system has been proposed in the paper. Performance-based approach for separation minimums selection takes into account errors of positioning methods, which mainly depends on surrounding environment. Values of separation minimums have been estimated based on performance of available UAV equipment.

Operation of many dynamic systems is connected with data processing and analysis. Presence of single value that is significantly different from other data in the set is one of the main problems of data processing. Presence of outliers in Unmanned Aerial System (UAS) data indicates about system unreliability that can be considered dangerous for all airspace users and reduce the safety of aviation. A set of simple statistical tests for outliers detection in UAS data was considered in the current study. UAS angular data has a cyclic scale and requires a specific approach for its processing. Parametric and non- parametric methods have been studied to detect outliers in UAS parameters with a cyclic scale. Results of k-sigma test for outliers detection in vehicle heading data gives maximal probability of correct detection and minimal values for false alarm and outlier omission.

Мета: Робота спрямована на те, щоб визначити штучний інтелект як ключовий пріоритет у питаннях досліджень та розробок. Розгляд існуючих методів виявлення об'єктів є одним з важливих завдань статті. Представлені результати досліджень спрямовані на дослідження проблеми виявлення рухомих об'єктів за допомогою даних візуальних датчиків для застосування у безпілотній авіаційній системі. Методи: представлений підхід грунтується на імовірнісних та статистичних методах обробки даних, зокрема використання підходу узагальнених канальних характеристик для виявлення об'єктів. Результати: Метод пошуку об'єктів за узагальненими канальними характеристиками за використанням відеопотоку з різними сценаріями був досліджений практичним способом. Результати експериментального дослідження використання узагальнених канальних характеристик для виявлення рухомих засобів транспорту, таких як автомобілів та трамваїв, свідчать про високі характеристики методу. Також досліджено залежність між часом тренування детектора та об'ємом позитивних екземплярів у конкретному випадку. Обговорення: Численні переваги методу виявлення об’єктів за узагальненими канальними характеристиками, такі як універсальність, простота реалізації та компроміс між часом обчислення та точністю виявлення, дозволяють використовувати його у завданнях виявлення людей, транспортних засобів, штучних та природних об'єктів для застосуванні у БАС. Представлені результати можуть бути впроваджені в безпілотні авіаційні системи для пошуку та моніторингу рухомих об'єктів.

The paper discusses the problem of statistical characteristics substantiation during radio equipment diagnostics. To provide serviceability and maintainability of radio equipment is one of the tasks of operation system. The operation system contains the processes of intended use of equipment, maintenance, running repair, continuation of life service and others. During running repair, the procedures of diagnostics, operability recovery and parameters monitoring are performed. The diagnostics process regulates the sequence of searching the failed element in the radio equipment scheme. The decision-making during diagnostics is associated with the errors of the first and second kind. So for efficiency analysis, the probability of correct diagnostics can be used. Such efficiency measure has random nature, but in the literature, only expected value is used to describe it. This paper concentrates on the approach to calculation of the probability density function for efficiency measure with purpose of obtaining the complete information about random value.

The paper deals with designing robust inertially stabilized platforms destined for functioning on the ground moving vehicles. The simulation model of the stabilization plant has been developed. The approach to the creation of the disturbances specific for ground vehicles is described. The algorithm of the design of the robust system has been developed. The basic steps of this algorithm are represented. Simulation of the synthesized inertially stabilized platform has been carried out.

Radio equipment for aircraft flight supporting consists of communication, navigation and surveillance devices. These devices are used to provide the safety and regularity of aircraft flights. During radio equipment operation the processes of intended use, maintenance, repair, continuation of life service are implemented. The decision-making about control and preventive actions for these processes is based on the results of statistical data processing. In such cases statistical methods with predetermined sample size are used. This paper concentrates on the problem of synthesis of sequential method that allows making decision faster for given level of data processing effectiveness. The researched sequential method is used for estimation of reliability parameters based on priory information about these parameters distribution and functional transformation of corresponding probability density function. During solving analysis problem, the probability density functions of estimate and observation duration are calculated.

Weather phenomena have significant influence into air traffic. Accuracy and continuity of meteorological data which are used in aviation specify flight safety. Nowadays, most of airports include meteorological stations. Results of current weather measurements are specified in meteorological aerodrome reports which are issued periodically and are shared with worldwide airspace users. In the paper we research an application of developed linear regression model for weather data interpolation and extrapolation by end-user equipment based on weather reports issued in half-hourly intervals. Proposed model uses a spline function as a regression function and supports multivariate data processing. Results of numerical application for continuous report reading during 24 hours for Boryspil airport indicate better performance of Bspline functions in comparison with polynomial functions.

Navigational aids network is an important component of a modern air navigation system which supports airplane navigation in airport areas by standard schemes and provides stand-by positioning capability for scenarios of primary on-board positioning system lock or malfunction. In the paper we consider a navigational aids network of each Air Navigation Service Provider (ANSP) within European airspace to provide overall configuration analysis. A network of Distance Measuring Equipment (DME) is analyzed based on the impact of particular ground transponder on positioning performance. An amount of DME pairs and impact of each transponder into the effective area of RNAV1 are used as criterions for configuration analysis of the network. The service area of navigational aids network is estimated based on the Standard service volume model of ground transponder. Also, we provide navigational aids network analysis based on graph theory. Navigational aids network is represented in the form of weighted graph to estimate centrality and betweenness for ranging network nodes. A graph of navigational aids includes edges between DMEs, which form pairs based on ICAO Doc. 1396 requirements. Obtained results of graph analysis help to identify service quality in the boundary area of the network. Graph analysis identifies network performance across European coastline, where DME service is limited. At the final stage, we provide an estimation of Horizontal dilution of precision coefficient to evaluate influence of the geometry of ground network configuration on positioning performance. Structure of each national network is composed in a different manner, due to variety of ANSP roadmaps and different periods of development that affect overall positioning performance. Obtained results of the analysis helps to highlight point for improvement in the development of European navigational aids network.

Air transport services compose a continuously growing transportation industry, which became closer to their operational perils. Classical air traffic management system includes a network of flight routes for performing civil airspace operation. In our study, we provide an analysis of flight routes network configuration based on graph theory. Ukrainian flight routes network has been represented in the form of a weighted planar graph. Measures of weighted, closeness, betweenness centrality and waypoints degree are used for configuration analysis. Also, an edge vector was statistically analyzed for Ukrainian flight routes network. Results of analysis identify the most loaded and frequently used waypoints based on network configuration. Obtained data are useful for the development of Ukrainian flight routes network and efficient flight traffic planning procedures.

Ukrainian navigational aids network has a long history of deployment and development. Currently, navigational aids network includes ground equipment of Distance Measuring Equipment (DME), Very high-frequency Omni-directional Ranging (VOR), and Non-Directional Beacons (NDB). In our research, we would like to provide an overall study of navigational aids network configuration to specify the impact of particular ground station on the service provided. Common models of navigational aids are considered to estimate navigational aids availability and efficient pair forming in case of positioning by DME/DME and VOR/VOR. An area of correspondence to RNAV requirements is used as a criterion to estimate the impact of each navigational aid on overall network performance. Also, the navigational aids network is represented in the form of a weighted graph to estimate characteristics of centrality and betweenness for ranging network nodes. Configuration of Ukrainian navigational aids network is studied as an example. Obtained results are useful for a better understanding of navigational aids network configuration.

In this paper, some cybersecurity vulnerabilities of modern UASs were considered. Vulnerabilities of communication, navigation, control, and surveillance equipment of modern UASs were analyzed. The cyber threats analysis and assessment algorithm were presented. The proposed algorithm is focusing on possible intruders’ portrait that can be important when qualitative risk assessment. The approach to assess the UASs cyber hazards connected with considered vulnerabilities and threats was made. It was stressed that the particular assessment highly depends on the properly defined mission, potential intruders, and even social and political situation. A short overview of the recommendations to mitigate risk connected with cyber hazards was done.

The paper deals with the problem of mathematical models building for diagnostic variables of radio electronic systems in the case of data heteroskedasticity. The heteroskedasticity is associated with event when clusters from single sample are characterized by different values of variance. In operation theory heteroskedasticity occurs in case of equipment technical condition deterioration. The paper describes the method for taking into account heteroskedasticity, which includes the following steps: building and choosing the best regression model; calculation of heteroskedasticity index based on minimization of weighted sum of residuals squares; determining correction coefficients of heteroskedasticity and obtaining the final regression equation. The proposed methods can be used during utilization of condition-based maintenance with diagnostic variables monitoring.

Distance Measuring Equipment is included into the main list of on-board navigation equipment of civil airplanes. Current performance-based navigation considers DME as a primary sensor for stand-by on-board positioning equipment. During the cycle of range measuring, on-board DME interrogator interacts with a ground-based navigational aids network. Accuracy of range measuring depends on performance and workload of navigational aids network. Navigation signals of Distance Measuring Equipment use Gaussian pulse-pairs form, which does not support signal identification in the ground-based transponder. We propose an algorithm for identification of Distance Measuring Equipment interrogations with a particular air space user. Proposed algorithm is based on navigation signal amplitude detection, clusterization by mean value, and interrogation identification with airspace users located in the operational range of navigational aid based on range criteria. A method of maximal posterior probability is used for interrogation identification with a particular airspace user, which supports recognition with the highest level of probability. Proposed algorithm was integrated into a passive system based on two Software Defined Radios for navigation signal monitoring. Integration of proposed algorithm at the software level of secondary data processing system in the national navigational aids network makes possible to provide user-based service analysis in order to improve overall network performance.

Algorithms of positioning by navigational aids are widely used as an alternative to Global Navigation Satellite System on-board of large airplanes. Distance measuring equipment is a commonly used navigational aid for alternative positioning by a pair of measured ranges. Errors of range measuring are directly connected with airplane localization in airspace and have primary influence in airplane trajectory maintaining as well as ensuring the required level of air traffic safety. The impact of errors of on-board positioning system into aviation safety is represented in the paper. A mid-air collision category of aviation safety is assessed based on risk of airplane unintentional deviation from planned location due to influence of on-board positioning system errors. Represented approach is grounded on location of a bivariate probability density function at each airspace user location and estimation of a probability of getting two airspace users within the same safety region. Airplanes separation minimums are used as size of the safety region. Numerical demonstration is provided by live air traffic data shared by Automatic Dependent Surveillance-Broadcast message and received by Software Defined Radio within a part of Ukrainian airspace volume. Risks of mid-air collisions for each pair of airspace users are estimated.

Performance-based navigation is grounded on wide usage of a pair of Distance Measuring Equipment (DME) as one of the alternative positioning methods on-board of an airplane in case of primary system malfunction. The flight measurement system automatically detects the most optimal pair of ground equipment to support positioning with high performance. A variety of available algorithms of DME selection logic may increase workload of some elements of the navigational aids network, due to the limited capacity of each transponder. In the paper, we propose a passive system for interrogation rate measurements and statistical analysis of navigational aids ground network performance. The system includes two software defined radios. One of them is used for receiving and processing of interrogation signals with DME capacity estimation. Another one detects air traffic data by receiving and decoding messages under automatic dependent surveillance broadcast. The interrogation rate in channels of Ukrainian navigational aids network has been measured and reply efficiency was estimated.

An air traffic delay is a common problem of a modern transport system. Continuously increasing demand of air traffic system and operation in a rapidly changing environment makes delay estimation is a key element in aviation safety. In the paper, we propose a light statistical method of airplane landing delay prediction at the destination airport. Proposed method grounds on statistical data processing of previous flights to identify mean trajectory of an airplane at the pre-flight stage and continuously comparison of mean trajectory with current airplane location in order to identify a time to land in the destination airport. A simple solution of minimization problem at the en-route phase of flight needs low computation power and guarantees the required confidence band for results. Proposed method has been trained on statistical data for Boryspil / Kharkiv connection routes in order to airplane delay prediction.

The probability of an airplane deviation from pre-planned trajectory is a core of aviation safety analysis. We propose to use a mixture of three probability density distribution functions it the task of aviation risk assessment. Proposed model takes into account the effect of navigation system error, flight technical error, and occurrence of rare events. Univariate Generalized Error Distribution is used as a basic component of distribution functions, that configures the error distribution model from the normal error distribution to double exponential distribution function. Statistical fitting of training sample by proposed Triple Univariate Generalized Error Distribution (TUGED) is supported by Maximum Likelihood Method. Optimal set of parameters is estimated by sequential approximation method with defined level of accuracy. The developed density model has been used in risk assessment of airplane lateral deviation from runway centreline during take-off and landing phases of flight. The efficiency of the developed model is approved by Chi-square, Akaike’s, and Bayes information criteria. The results of TUGED fitting indicate better performance in comparison with double probability density distribution model. The risk of airplane veering off the runway is considered as the probability of a rare event occurrence and is estimated as an area under the TUGED.

The paper considers a problem of aircraft positioning, especially stand-by or alternative to global navigation satellite system methods of aircraft coordinates determination in airspace. Interference with electronic equipment and jamming produced by personal devices have been discussed as main causes that may lead to complete lock of GNSS positioning function. Paper is devoted to important issue that is connected with reducing of positioning accuracy that is the main peril for future development of future air navigation infrastructure and decreases safety of aviation. Paper represents an analysis of prospective methods that use pairs of navigational aids of area navigation that includes usage of Distance Measurement Equipment, VHF Omni Range, and Non Directional Beacon data. Several possible ways of accuracy improving of distance measurement equipment were analyzed that can increase accuracy of positioning by area navigational aids. For instance, usage of modern digital equipment and changing the parameters of navigation signal can be used to achieve the required navigation characteristics. Wide area of multilateration, passive positioning approach, pseudo-satellite, MOSAIC/DME and diverse ranging methods are considered as possible future alternatives to GNSS in aviation. Their advantages and disadvantages are considered in the article. General classification of aircraft positioning methods, including area navigation algorithms is developed. Study outcomes of future positioning approaches indicate that current air navigation infrastructure of navigational aids does not meet requirements of precise future area navigation. Proposed solution for this problem is to introduce completely modern systems grounded on pseudo-satellite principle or wide area multilateration, but it requires absolutely new navigation equipment. As a result, in the future, a revision of the minimum equipment list will be required due to necessity to use new avionics systems in order to ensure accuracy requirements that can create inconvenience for air carriers.

Мета: Представлені результати досліджень спрямовані на формулювання задачі оптимізації мережі наземних радіо-навігаційних засобів з метою підвищення ефективності наданих навігаційних послуг. Запропонований підхід базується на ітеративному підході на основі ефективності позиціонування в кожній точці повітряного простору та подальшому вибору найбільш оптимального місця для нового радіонавігаційного засобу. Методи: представлений підхід ґрунтується на аналітичних та статистичних методах оцінювання точності позиціонування, методах теорії цілочисленого лінійного програмування та комп'ютерного моделювання на етапі верифікації результатів. Результати: мережа наземних раді-навігаційних засобів розглядається у вигляді геометричної сукупності стандартних об’ємів простору у межах яких забезпечується належне їх функціонування у три-мірному просторі. Місця можливого розташування нової наземної станції розглядаються разом з існуючою мережею навігаційних засобів. Оптимальне розташування нової наземної станції навігаційних засобів є результатом мінімізації цільової функції з певними обмеженнями. Зважені коефіцієнти лінійної цільової функції відображають характеристики позиціонування за навігаційними засобами. Результати рішення задачі оптимізації в термінах лінійного програмування забезпечать найбільш оптимальне розташування нової наземної станції з ряду можливих координат. Обговорення: Формулювання задачі оптимізації в термінах двійкового цілочисленного лінійного програмування представляє собою проблему оптимального пошуку місця розташування нових радіо-навігаційних засобів за допомогою однієї лінійної функції та обмежень, для вирішення якої можуть застосовуватись різні математичні методи. Отримані результати можуть бути застосовані під час проектування повітряного простору та модернізації мережі наземних радіо-навігаційних засобів.

Мета: представлені результати досліджень спрямовані на розробку нового методу позиціонування, що використовує сигнали DME в просторі та повідомлення ADS-B від користувачів повітряного простору. Запропонований підхід позиціонування базується на зборі та аналізі сигналів. Один літак, що взаємодіє з двома різними DME, є джерелом трьох гіперболічних ліній розташування, перетин яких може вказувати на розташування користувача. Методи дослідження: представлений підхід ґрунтується на використанні різницево-далекомірному методу, статистичних методах оцінки похибок та комп'ютерному моделюванні. Результати: запропонований метод виявлення координат літальних апаратів може зменшити навантаження на наземну мережу DME, оскільки він базується на пасивному спостереженні сигналів DME, присутніх у повітряному просторі. Обговорення: Підхід може бути застосований в алгоритмах обчислювальної системи літаководіння у якості альтернативного методу позиціонування до існуючих.

Purpose: The represented research results are aimed to formulate an optimization task of ground based navigational aids network in order to improve performance of provided navigational service. Proposed approach is based on iterative process with estimation performance of positioning in each point of airspace and further selection of the most optimal location for new ground facilities. Methods: Represented approach is grounded on analytical and statistical methods of positioning estimation performance, binary integer linear programing theory, and computer-based simulation at verification stage of development. Results: Ground navigational aids network has been represented as a set of geometrical location of standard service volumes in tree-dimensional space. The possible locations for new ground stations were considered together with an existing navigational aids network. The optimal location of new ground stations of navigational aids are result of objective function maximization with specific constraints. Weighted coefficients of linear objective function indicate a volume of predefined performance level of positioning by navigational aids. Results of optimization task solution in terms of linear programming will provide the most optimal location for new ground station within a pool of possible coordinates. Discussion: Formulation of optimization task in terms of binary integer linear programing represents the problem of optimal location search for new navigational aids in one linear objective function and constraints that can be solved by various math methods. Represented results can be implemented during airspace design and in the development of navigational aids network.