Aircraft Operations Research Articles

PELAYANAN SAFETY RISK MANAJEMEN PESAWAT UDARA TANPA AWAK (PUTA) OLEH PERUM LEMBAGA PENYELENGGARA PELAYANAN NAVIGASI PENERBANGAN INDONESIA (LPPNPI) AIRNAV INDONESIA CABANG PEMBANTU PADANG

Unmanned Aerial Vehicles (PUTA) or drones have increasingly dominated various sectors, from surveillance mapping to sending goods from one place to another. The sustainability and operational security of PUTA requires effective and efficient safety assessment services. This research aims to evaluate the safety assessment service for unmanned aircraft or drones at Perum LPPNPI AirNav Indonesia Padang Sub-Branch. The research methodology involves analysis of operational data, interviews with related parties and evaluation of compliance with safety standards. The research results show that safety risk management services for unmanned aerial vehicles or drones at the Padang Sub-Branch have experienced significant development, however there are still challenges in managing PUTA operational safety risks as a whole. In implementing the Safety Risk Management Service, several aspects were found that needed further attention, including the development of a monitoring system and increased involvement of related parties, as well as understanding the operational characteristics of PUTA in the Padang Sub-Branch work area. It is hoped that the results of this research can provide an important contribution in improving the safety of unmanned aircraft operations at the Padang sub-branch and provide a basis for developing better safety assessment services in the future.

A Deep Learning Framework for Real-Time Bird Detection and Its Implications for Reducing Bird Strike Incidents.

Bird strikes are a substantial aviation safety issue that can result in serious harm to aircraft components and even passenger deaths. In response to this increased tendency, the implementation of new and more efficient detection and prevention technologies becomes urgent. The paper presents a novel deep learning model which is developed to detect and alleviate bird strike issues in airport conditions boosting aircraft safety. Based on an extensive database of bird images having different species and flight patterns, the research adopts sophisticated image augmentation techniques which generate multiple scenarios of aircraft operation ensuring that the model is robust under different conditions. The methodology evolved around the building of a spatiotemporal convolutional neural network which employs spatial attention structures together with dynamic temporal processing to precisely recognize flying birds. One of the most important features of this research is the architecture of its dual-focus model which consists of two components, the attention-based temporal analysis network and the convolutional neural network with spatial awareness. The model's architecture can identify specific features nested in a crowded and shifting backdrop, thereby lowering false positives and improving detection accuracy. The mechanisms of attention of this model itself enhance the model's focus by identifying vital features of bird flight patterns that are crucial. The results are that the proposed model achieves better performance in terms of accuracy and real time responses than the existing bird detection systems. The ablation study demonstrates the indispensable roles of each component, confirming their synergistic effect on improving detection performance. The research substantiates the model's applicability as a part of airport bird strike surveillance system, providing an alternative to the prevention strategy. This work benefits from the unique deep learning feature application, which leads to a large-scale and reliable tool for dealing with the bird strike problem.

Impact characteristics of S2-glass fibre/FM94-epoxy composites under high and cryogenic temperatures: Experimental and numerical investigation

The aerospace industry uses glass fibre reinforced polymer (GFRP) composites to manufacture structural and non-structural parts of an aircraft as they possess superior strength to weight ratio and exceptional corrosion resistance. Commercial aircraft operate in a very wide temperature ranges from −54 to 55 °C. Potential GFRP laminates are susceptible to impact during aircraft operation, and the temperature at impact governs the nature of damage and failure mechanisms. As a result, the current study focuses on examining how aeronautical GFRP composites behave in various temperature environments that are encountered during high- and low-altitude operations. Using S2-glass fibre/FM94-epoxy unidirectional prepreg, GFRP plates were created. Drop weight impact tests were conducted at ambient (25 °C), high (50, 75, 100 °C), and low (−25, −55 °C) temperatures, as well as at various impact energies (75, 150, 225 J). The damages were assessed visually, along with their sizes. Each testing scenario's impact parameters, including the impact load, deflection, and energy absorption, were also examined. In Abaqus/Explicit, a coupled temperature-displacement numerical model was created to predict the onset of stress and damage. According to experimental findings, GFRP plates are stiffer and show less apparent damage at cryogenic temperatures (∼15−34 % lower displacement) than they do at other temperatures. Furthermore, it was observed that the matrix softens at high temperatures, showing larger damaged area at entry but with less obvious damage and increasing energy absorption, while semi-perforation occurred under cryogenic temperatures at entry with smaller damaged area. A strong correlation is shown between the experimental and FE data, confirming the capability of FE models to predict impact damage and deflections at different temperatures in the future.

Surface roughness effects on transonic aircraft performance: Experimental/numerical comparisons

This work highlights the necessity of taking into account surface roughness when conducting experimental tests, and when using numerical simulations to precisely calculate the turbulent lift and drag of wind-tunnel models or real aircraft in transonic conditions. The present article is a continuation of “Turbulent drag induced by low surface roughness at transonic speeds: Experimental/numerical comparisons,” Physics of Fluids, Vol. 32, 045108 (2020) by Hue and Molton. The outcomes of this former study, which was focused on flat plate samples, are here applied to a three-dimensional aircraft configuration: the Common Research Model used as a reference in the recent international Drag Prediction Workshops. Experimental campaigns have been performed in the largest ONERA wind tunnels S1MA and S2MA involving models with average surface roughness heights Ra close to 0.5 micrometers, wingspans up to 3.5 meters, Mach and Reynolds numbers up to 0.95 and 5 million respectively. Reynolds-averaged Navier–Stokes computations based on the wind-tunnel tests have then been carried out, using the equivalent sand-grain roughness height approach as well as a Musker-type correlation to determine relevant ks values. The results of both the experimental and numerical campaigns have demonstrated that the aerodynamic coefficients of the aircraft can be significantly affected by the surface roughness, even with roughness Reynolds numbers ks+ potentially below the usual threshold values sometimes considered in engineering applications (i.e. in the order of 3.5 to 5). In particular, the surface roughness effects on lift and drag have been studied using far-field analyses to evaluate the responses of friction, viscous pressure, wave and lift-induced drag components. Finally, the numerical studies have been extended to the full-scale geometry in flight conditions in order to assess the roughness effects and potential gains in realistic aircraft operating conditions.

Environmental hazard assessment of forest fire sites to firefighting aircraft—part I: Canyon wind and temperature distribution

Wildfires have caused immense damage to the environment, property and human safety in recent years. Fortunately, the deployment of firefighting aircraft, particularly water bombers, has emerged as one of the most effective strategies for combating wildfires. However, the intricate environment of forest fire sites, characterized by thermal turbulence and canyon winds, presents a formidable flight risk for firefighting aircraft. To address this issue, this study conducted a comprehensive risk assessment of firefighting aircraft operating in a wildfire environment, analyzing the impact of thermal turbulence and canyon winds using a finite element simulation method. This approach not only bridges the research gap in the field of flight safety but also evaluates the environmental risks encountered by firefighting aircraft when entering forest fire sites. Our findings underscore thermal turbulence and canyon winds as potential hazards for aircraft flying over mountainous terrain, elucidating the effect of thermal turbulence on aircraft engine intakes and quantifying the total lift loss incurred during encounters with canyon winds featuring non-uniform airflow velocities. Specifically, thermal turbulence can induce instability and vibration in aircraft engines, whereas canyon winds can generate updrafts and downdrafts that may compromise aircraft structures or lead to lift loss. Furthermore, we cite several references to emphasize the multifaceted risks associated with the forest fire site environment, encompassing temperature gradients, thunderstorms, and air pollution. Such comprehensive wildfire data can be invaluable in assessing the flight safety of firefighting aircraft during water-dropping missions in forest fire scenarios.

Research on the Collision Risk of Fusion Operation of Manned Aircraft and Unmanned Aircraft at Zigong Airport.

Low-altitude airspace is developing rapidly, but the utilization rate of airspace resources is low. Therefore, in order to solve the problem of the safe operation of the fusion of large UAVs and manned aircraft in the same airspace, this paper analyzes the theoretical calculation of the collision risk of the fusion operation of manned aircraft and UAVs at Feng Ming Airport in Zigong, verifying that while assessing the safety spacing of 10 km in the lateral direction, it further simulates the possibility of calculating the theoretical smaller safety spacing. The study will propose a new theory of error spacing safety margin and improve it according to the traditional Event collision risk model, combining the error spacing safety margin to establish an improved collision model more suitable for the fusion operation of manned and unmanned aircraft and reduce the redundancy of calculation. The error factors affecting manned and unmanned aircraft at Zigong Airport are analyzed, and theoretical calculations are analyzed by combining the actual data of Zigong Airport. Finally, the Monte Carlo simulation method is used to solve the error, substitute the calculation results, and simulate a section of the trajectory of the fusion operation for the reverse argument. The theoretical calculation results show that the collision risk from 10 km to 8 km satisfies the lateral target safety level (TSL) specified by ICAO under both traditional and improved models. The collision risk calculated by the improved model incorporating the error spacing safety margin is smaller, which enhances the safety of the model calculations. The results of the study can provide theoretical references for the fusion operation of manned and unmanned aircraft.

Resilience assessment of airport aircraft area network operations under thunderstorm weather

Thunderstorms can cause a decrease in airports' dynamic capacity, and taxiway runway capacity is a key element of airport airfield operations. In this paper, based on the cell transmission model (CTM), the meteorological operation parameters of thunderstorms are set according to the airport aircraft taxiing rules, and a CTM is proposed for evaluating the resilience of the airport aircraft area operation network under thunderstorm weather. Based on the CTM, the network performance parameters are obtained, and the number of aircraft waiting for the network and the network operation efficiency are used as the basic performance indicators to establish a resilience index that reflects the dynamic change in the resilience of the thunderstorm meteorological interference network. Finally, this paper collects and analyzes the operation data of Tianjin Binhai International Airport in 2019 to build a CTM for aircraft operation in the flight area. The results show that the model's simulated airport departure operation data is almost consistent with the trend of the actual departure operation data, which verifies that the model can be used to simulate traffic for the airport airfield operation network. In addition, based on the resilience index, the sensitivity analysis of different parameters to network performance under thunderstorm weather was also studied. Based on the evaluation results of different parameter scenarios and indicators, we drew the resilience map of the airport ground operation network, and found that the network shows different resilience levels in different thunderstorm level scenarios. This study provides a great method and evaluation index for modeling and resilience evaluation of aircraft operation networks in the airfield, which is expected to improve airport operations, reduce flight delays, and improve service quality.

Electrophoretic deposition of CNTs on a Cu foam interlayer for enhancing Cf/SiC–Nb brazed joint performance

The high residual stress and low toughness of ceramic matrix composite/metallic brazed joints poses severe challenges for the stable operation of high-speed aircraft under harsh conditions. This article innovatively tackles this issue with electrophoretic deposition (EPD), creating a CNT covered Cu foam composite interlayer for brazing Cf/SiC and Nb with an Ag–Cu–Ti alloy filler. A layer of mass ratio-controllable and percolated CNTs was physically adsorbed on the surface of the Cu foam substrate. EPD time was systematically investigated for its impact on the microstructure and mechanical properties of the joints. Results indicate that during brazing, the CNTs reacted with the active Ti element, transforming into ultrafine TiC grains with particle sizes ranging from 6 to 16 nm. These were dispersed evenly in the Ag solid solution. The elastic recovery rate of the cluster regions showed an increase of 123 % compared to the Ag solid solution, showing improved toughness of the seam. When the EPD time was 80 min, the shear strength of the joint produced with the composite interlayer reached 128.6 MPa, a 69 % increase over the directly brazed joint. Moreover, the fracture location of the joint shifted from the brazed seam towards the interior of the bulk Cf/SiC. Additionally, finite element analysis was utilized to confirm a significant decrease in residual stresses within the joint, and verified the findings.

On a fair and risk‐averse urban air mobility resource allocation problem under demand and capacity uncertainties

AbstractUrban air mobility (UAM) is an emerging air transportation mode to alleviate the ground traffic burden and achieve zero direct aviation emissions. Due to the potential economic scaling effects, the UAM traffic flow is expected to increase dramatically once implemented, and its market can be substantially large. To be prepared for the era of UAM, we study the fair and risk‐averse urban air mobility resource allocation model (FairUAM) under passenger demand and airspace capacity uncertainties for fair, safe, and efficient aircraft operations. FairUAM is a two‐stage model, where the first stage is the aircraft resource allocation, and the second stage is to fairly and efficiently assign the ground and airspace delays to each aircraft provided the realization of random airspace capacities and passenger demand. We show that FairUAM is NP‐hard even when there is no delay assignment decision or no aircraft allocation decision. Thus, we recast FairUAM as a mixed‐integer linear program (MILP) and explore model properties and strengthen the model formulation by developing multiple families of valid inequalities. The stronger formulation allows us to develop a customized exact decomposition algorithm with both benders and L‐shaped cuts, which significantly outperforms the off‐the‐shelf solvers. Finally, we numerically demonstrate the effectiveness of the proposed method and draw managerial insights when applying FairUAM to a real‐world network.

Understanding no fault found event risk in military aircraft MRO planning: A step towards robust bidding and contract finalization

No fault found (NFF) is a reported fault for which the root cause cannot be found. An NFF event not only reduces the availability of the equipment to customers but also results in financial losses to the manufacturer. To date, risk due to NFF events is not considered separately in aircraft Maintenance, Repair, and Overhaul (MRO) planning. In this paper, we have studied the NFF event risk identification, distribution, and optimization in an aircraft MRO process based on data collected over three decades of aircraft maintenance. For framework development and formulating the critical NFF risk drivers, this paper applies soft system methodology with detailed semi-structured interviews of industry experts. For NFF risk distribution and optimization, we have used agent-based simulation modeling. The quantitative assessment of more than 5000 NFF cases in an aircraft MRO organization shows that NFF events are significantly non-deterministic during the life cycle of an aircraft. The three identified critical NFF risk drivers in the research are the MRO process stage, aircraft life cycle stage, and human working skills. The MRO process stage is the time of the NFF event during repair activity. The life cycle stage represents the timeline of the NFF event in useful aircraft life. Human working skill represents the role of manpower in the NFF event solution. Further theoretical elaborations of the research lead to the optimized NFF risk break-up at the contract preparation stage and risk driver's sensitivity analysis by the aircraft assembler, operator, and sub-contractor at the commercial bid submission stage.

Realizing a 21st Century Noise Policy

Aviation noise impacts affect the health and quality of life of communities nationwide. The FAA's noise policy, last updated in the 1970s, uses a single decision-making metric (DNL), to determine the significance of noise impacts caused by aircraft operations. The Neighborhood Environmental Survey (NES), released in 2021, shows that many more people are impacted by aircraft noise and at levels far below 65 dB DNL than previously thought. The current noise policy does not reflect the 21st century airspace environment, including the consequences of NextGen and the tremendous growth in air traffic. An important improvement to realize an up-to-date noise policy is to reflect the lived experience of impacted communities more accurately. This paper will cover how communities experience aircraft noise in two separate noise exposure environments both near and away from airports, which practices are issues and most concerning to communities, what metrics more accurately evaluate impacts, and how a more community-centric approach provides a better representation of the aviation noise experienced by people, which is fundamental to operating a National Airspace System that works for all.

On the modeling of urban air mobility vehicle takeoff and landing operations in the FAA Aviation Environmental Design Tool

Urban air mobility (UAM) vehicles are anticipated to operate in close proximity to the public. A possible barrier to the introduction of UAM vehicles as a transit solution is their community noise impact, particularly around vertiports. The Federal Aviation Administration Aviation Environmental Design Tool (AEDT) is the mandated tool to assess aircraft noise and other environmental impacts due to federal actions at civilian airports, vertiports, or in U.S. airspace for commercial flight operations. However, AEDT was designed to model fixed-wing aircraft and conventional helicopter operations, not UAM vehicles. Prior work by the authors showed significant differences in noise contours of UAM departures and approaches when modeling operations as fixed-wing and helicopter types in AEDT. This paper identifies the sources of those differences. Additionally, a NASA time-marching simulation tool is used to generate noise exposure data for equivalent operations to help identify differences associated with the integrated noise model implemented in AEDT and offer possible changes to assess UAM community noise impact more consistently with simulation-based modeling.

Trends and relationships between airport operations and noise complaints in Maryland between 2016 and 2023

The noise pollution from aircraft near airports significantly affects the health and quality of life of the local community either near or far away. This study analyzes trends in airport noise complaints in Maryland from 2016-2018. Data on noise complaints were extracted from airport noise quarterly reports and the data included the number of complaints and unique complaints from different communities near airports, as well as average aircraft operations. The number of complaints rose from less than 1,000 in 2016 to nearly 10,000 in 2018. This study aims to identify the communities most impacted by increasing airport noise through descriptive and geospatial analysis of complaint data. Results will highlight high-complaint areas to inform future noise mitigation policies and airport expansions in Maryland. The number of noise complaints increased drastically from 2016-2018, while flight operations remained steady. Correlational analyses examine the strength of relationship between flight volume and complaint volume over time. Boeing 737-700 operations has the most significant relationship with the number of unique complainants around Baltimore/Washington International Airport. Results will help inform policies to mitigate noise impacts by identifying whether reducing operations, changing flight paths, or other strategies could effectively reduce complaints as well as help the meeting the noise reduction design goals of the state.

THE IMPORTANCE AND EFFECTIVENESS OF CREW RESOURCE MANAGEMENT (CRM) IN RUSSIAN AVIATION

The modern air transport system is characterized by a great dependence on humans and the safe functioning of all its elements is determined by the “human factor”, which plays a major role in the management and stability of the entire system. With the passage of time and the development of the aviation industry, the role of the human factor in aviation accidents has significantly increased and changed. This article is devoted to the need for effective management of the resources of the crew (cabin) of an aircraft, in particular, the formation of systematic knowledge about the basic requirements and features, ensuring the safe operation of civil aviation aircraft.

Particle Image Velocimetry Investigation Of The Aerodynamic Interaction Between Helicopter And An Aircraft Carrier

Helicopters greatly expand operational capabilities during military missions at the sea. The aircraft carriers are capable of accommodating fixed-wing and rotary-wing aircraft operations. They not only have one runway for take-off, but also have different spots for helicopter operations. As they are spread over the deck of the aircraft carrier, the non-aerodynamic geometries of the take-off ramp and the island can generate complex flows, with high velocity gradients and turbulence intensities that can make complex the helicopter landing and take-off maneuvers for pilots. This study analyses the interaction between the aerodynamic patterns generated by the warship and those generated during the operation of the helicopter. Two wind conditions are simulated: headwind and crosswind. The results are provided by a Particle Image Velocimetry (PIV) system installed at the wind tunnel test section of a low-speed wind tunnel. The model of aircraft carrier and helicopter are tested in a reduced scale of 1:100. And the helicopter rotor rotates at sufficient speed to ensure the similarity of the thrust coefficient with the real case. Finally, during the wind tunnel tests, using an automatic positioning system, the helicopter is placed in different positions above the aircraft carrier flight deck in order to obtain PIV images and extract non-dimensional velocity contours with and without the helicopter effect. The results have shown important effects of the aerodynamics generated by the bow, the hull and the aircraft carrier island, with velocity differences up to 70 % depending on the landing spot analyzed.

Flying in the Strike Zone: Urban Air Mobility and Wildlife Strike Prevention

The number and rate of wildlife strikes continue to increase worldwide. More than 30 years of wildlife strike data indicate that approximately 92% of wildlife strikes for commercial aircraft occur at or below 3500 ft above ground level. Since urban air mobility (UAM) operations are envisioned to carry cargo and passengers up to an altitude of 4000 ft above ground level, UAM operations will face increased exposure to wildlife strike risks throughout their operations. Moreover, the comparatively small size of UAM aircraft, proposed cruising speeds of up to 170 kt, and quieter electric engines are expected to reduce opportunities for threat perception and evasive maneuvers by aircraft operators and wildlife. This paper presents how well-established wildlife strike prevention measures can be adapted to meet the needs of UAM operations and how, with new technology, original equipment manufacturers (OEMs), regulatory agencies, aircraft operators, communities, airspace managers, and vertiport operators can work together to enhance safety.

Bird Strike Test Event Diagnosis Using a Hybrid SHM System

Several advances have been made in the recent years in the integration of Structural Health Monitoring (SHM) systems within Structural Integrity (SI) management. The current state-of-the-art Airbus Defence and Space (ADS) SHM System relies on both an analytical elastic wave propagation model and a Dynamic Distributed Fibre Optics Sensing (DFOS) Environmental and Operational Conditions (EOC) measurement and compensation model. This hybrid SHM system is able to properly diagnose mechanical impacts (events) and resulting damages that may occur during aircraft operation, while accounting for punctual alterations in the structure due to changes in ambient temperature or pressure. In this paper, a demonstrative application of this system is presented for the diagnosis of a Bird Strike Test Event. The test has been carried out in controlled conditions for a hybrid metal-composite fuselage cockpit structure, within the scope of CS2 PASSARO EU program. The results show the reliability of the ADS SHM system for supervised conditions.

Guided Ultrasonic Wave Monitoring of Damage in Anisotropic Composites

Lightweight, carbon fibre reinforced composites are often employed for the manufacture of aerospace components due to their good strength to weight ratio. However, due to poor interlaminar strength, composite components are prone to barely visible impact damage, caused by low velocity impacts, during aircraft operation. Guided-wave-based structural health monitoring (SHM) techniques, using a network of distributed sensors, is an important Structural Health Monitoring (SHM) tool for the detection and localization of in-service impact damage in composite structures. However, the material anisotropy of composite laminates influences guided wave propagation and scattering. These anisotropic effects, if unaccounted for, could lead to inaccurate localization of damage, and potential regions of the structure where guided waves cannot propagate with sufficient amplitude, reducing damage sensitivity. Defect characterization can be improved by considering the scattering characteristics of various damage types for the sparse array signal processing. Guided wave scattering (A0 Lamb wave mode) was investigated around an artificial insert delamination in a quasi-isotropic CFRP panel. Permanent magnets, mounted on an undamaged region of the plate, were also used as scattering targets and compared to the delamination case. Full 3D Finite Element (FE) simulations were performed for both the delamination and magnet cases and compared to wavefield data obtained from non-contact laser Doppler vibrometer (LDV) measurements. Individual ply layers were modelled using unidirectional composite material properties to accurately capture the anisotropy effects. Good agreement was found between the experimental measurements and simulations. Scattered guided wave amplitudes around each damage type show strong directional dependency with energy focusing along the fiber directions of the outer ply layers of the laminate. Distinct scattering behavior was observed for each damage type. Implications of anisotropy and angular scattering on sparse array SHM of different defect types are discussed.

Integrated Model for Predicting Demand of Supersonic Transports Under Low-Boom Constraint

Commercial supersonic aircraft could return between 2035 and 2040 due to the desire for fast travel and advancements in technology that could reduce the cost of supersonic transport. Nevertheless, several challenges remain to make supersonic travel a reality. This paper presents an integrated model that ties the aircraft preliminary design process, the economics of aircraft development and operations, and passenger preferences to estimate worldwide demand for subsonic overland, Mach cutoff, and low-boom aircraft design concepts. This comprehensive and iterative methodology takes into account the uncertainty of market demand for supersonic travel and the complexities of supersonic network operations. Based on the study of four conceptual supersonic designs, we found that low-boom aircraft could attract 28% more demand worldwide compared to an optimized Mach cutoff design because of the additional time-saving benefits on overland routes. The results of this work offer valuable guidance to aircraft designers by explicitly tying the technical parameters of a design and the potential market demand. In addition, the integrated model developed may streamline the initial design development cycle by quantifying fleet size as part of an integrated modeling process.

Optimizing Structural Integrity of Fighter Aircraft Wing Stations: a Finite Element Analysis Approach

Modern fighter aircraft are equipped with multiple stations on the fuselage and under the wings to accommodate various external stores, both jettisonable and non-jettisonable. Each configuration undergoes airworthiness certification, including structural analysis of individual stations within the carriage flight envelope. This study focuses on the structural analysis of a fighter aircraft wing station within this specified envelope. To perform this analysis, the wing station is extracted from the comprehensive global wing model, creating a sub-model with equivalent stiffness properties. Utilizing ANSYS Workbench®, Finite Element Analysis (FEA) is conducted for critical load cases to determine the Factor of Safety (FoS). The initial analysis reveals that the wing station has an FoS of 1.2 under the maximum design load. Prestressed modal and buckling analyses indicate a 10% increase in stiffness due to stress-stiffening effects. To further enhance load-carrying capacity, parametric design changes are introduced. Increasing the bolt diameter from 8 mm to 10 mm raises the FoS to 1.33, resulting in an 8% increase in the maximum load-carrying capacity of the wing station. This comprehensive approach, employing FEA, ensures the wing’s structural integrity under static load conditions within the carriage envelope. The study's findings support the wing station's enhanced performance and contribute to safer and more efficient aircraft operations.