Long-haul Flights Research Articles

Travel option-based environmental comparison between passenger aircraft and high-speed rail

The short-haul flights have higher emission values than medium or long-haul flights when emissions per distance are considered. In this study, the potential to reduce greenhouse gas emissions by replacing short-haul flights which carried out by a narrow-body commercial aircraft from/to Konya City in Turkey with regional jets or high-speed trains (HSRs) has been investigated. The flight trajectory is selected from Konya Airport to İstanbul Sabiha Gökçen Airport, and that trajectory is a frequently performed domestic flight between Konya and İstanbul. The IMPACT platform is used for the calculation of fuel burn and gas emissions. According to the results, traveling with regional jets or high-speed trains from/to Konya City which is the most 15th polluted city in Europe, provides advantages in terms of environmental impact. Traveling with HSR which is the best traveling option in this study, provides approximately 3.3 times more green travel than the currently used narrow-body passenger aircraft between Konya and İstanbul. In addition, this mode of transportation can become more environmentally friendly by using renewable energy sources to produce its electricity needs. It is expected that this study will serve as a guide for airline and high-speed rail operators and regulators to determine the most environmentally efficient travel options based on fuel burn and emission parameters.

Prototyping Apps for the Management of Sleep, Fatigue, and Behavioral Health in Austere Far-Forward Environments: Development Study.

Military service inherently includes frequent periods of high-stress training, operational tempo, and sustained deployments to austere far-forward environments. These occupational requirements can contribute to acute and chronic sleep disruption, fatigue, and behavioral health challenges related to acute and chronic stress and disruption of team dynamics. To date, there is no centralized mobile health platform that supports self- and supervised detection, monitoring, and management of sleep and behavioral health issues in garrison and during and after deployments. The objective of this study was to adapt a clinical decision support platform for use outside clinical settings, in garrison, and during field exercises by medics and soldiers to monitor and manage sleep and behavioral health in operational settings. To adapt an existing clinical decision support digital health platform, we first gathered system, content, and context-related requirements for a sleep and behavioral health management system from experts. Sleep and behavioral health assessments were then adapted for prospective digital data capture. Evidence-based and operationally relevant educational and interventional modules were formatted for digital delivery. These modules addressed the management and mitigation of sleep, circadian challenges, fatigue, stress responses, and team communication. Connectivity protocols were adapted to accommodate the absence of cellular or Wi-Fi access in deployed settings. The resulting apps were then tested in garrison and during 2 separate field exercises. Based on identified requirements, 2 Android smartphone apps were adapted for self-monitoring and management for soldiers (Soldier app) and team supervision and intervention by medics (Medic app). A total of 246 soldiers, including 28 medics, received training on how to use the apps. Both apps function as expected under conditions of limited connectivity during field exercises. Areas for future technology enhancement were also identified. We demonstrated the feasibility of adapting a clinical decision support platform into Android smartphone-based apps to collect, save, and synthesize sleep and behavioral health data, as well as share data using adaptive data transfer protocols when Wi-Fi or cellular data are unavailable. The AIRE (Autonomous Connectivity Independent System for Remote Environments) prototype offers a novel self-management and supervised tool to augment capabilities for prospective monitoring, detection, and intervention for emerging sleep, fatigue, and behavioral health issues that are common in military and nonmilitary high-tempo occupations (eg, submarines, long-haul flights, space stations, and oil rigs) where medical expertise is limited.

Development of Low Emission Combustion Technologies For Modern Aero Gas Turbine Engines: An Overview

The demand for gas turbines for civil aviation is increasing continuously as the air transportation system is changing exponentially. Large fleet of commercial aircraft and large and long-haul flight have raised the demand on high thrust engines. Therefore, focus on fuel efficiency of the engines and control on exhaust gas emissions are increasing keeping in mind the economy and environmental considerations. International Civil Aviation Organization has promulgated the emission levels for civil subsonic turbojet and turbofan engines and making it more and more stringent day by day. This paper overviews various combustor technologies which have been developed over previous decades and are under development currently for present and future aircraft to meet the low emission goals.

The impact of fossil jet fuel emissions at altitude on climate change: A life cycle assessment study of a long-haul flight at different time horizons

Air traffic has increased by about 60% between 2011 and 2019 and climate forcers from aviation have also increased, resulting in a strong impact on climate change. It is well established that CO2 is the largest climate forcing component connected with aviation and its impact is now well calculated and documented. However, other climate forcers such as nitrogen oxides (NO and NO2), although not considered as greenhouse gases by the Kyoto Protocol, have a significant indirect impact on climate change. Post-combustion of the most common fossil fuel, Jet A-1, results in emissions of carbon dioxide (CO2), water vapor (H2O), volatile organic compounds (VOCs), sulfate ions (SO42−), carbon monoxide (CO), nitrogen oxides (NOx) and soot. Soot and water vapor emissions can trigger the formation of contrails-cirrus. Due to differences in lifetimes, temperature, pressure, humidity, and reactivity, all these climate forcers have not the same impact on climate change. Since 80% aviation fuel is burned during the cruise phase, this paper aims to improve the environmental assessment of the altitude emissions of the Jet A-1 fossil fuel, using Life Cycle Assessment (LCA) methodology. This method is a reference for calculating the environmental impact of air transport emissions. However, when it comes to assessing the impact of emissions at altitude, LCA models only take into account the impact of CO2 on climate change. New global warming potentials (GWP) and emission indices (EI) of climate forcing components related to air traffic were therefore included in our calculations to estimate the climate impact ICC at two different time horizons. In this paper, we show that the inclusion of non-CO2 effects results in an increase in the ICC at the 100- and 20-year THs of 115% and 517%, respectively. This considerable increase illustrates the crucial role of short-lived climate forcers that may have a greater impact when a shorter time horizon of 20 years is chosen.

The Trend of Bypass Ratio in Aero Engines: An Overview

The demand for turbofan engines for civil aviation is increasing continuously as the air transportation system is changing exponentially. Large and long-haul flight have raised the demand on high thrust engines. But at the same time, focus on fuel efficiency of the engines and control on exhaust gas emissions and noise are increasing keeping in mind the economy and environmental considerations. International Civil Aviation Organization has promulgated the emission and noise levels for civil turbofan engines and making it more and more stringent day by day. This has made an increasing trend of engine bypass ratio to address the fuel efficiency and the noise level of the engine. On the other hand, combat aircraft need to have high ‘g’ manoeuvrability, a faster response to throttle adjustment and high thrust-weight ratio thus preferring a low-bypass ratio world-wide. This paper covers the history of turbofan engines staring from its inception and presents the trend of bypass ratio in aero engines for both transport and combat aircraft. The paper also highlights the current developments and upcoming ultra-high bypass turbofan engine programs along with aircraft noise standards.

Consequences of migratory distance, habitat distribution and season on the migratory process in a short distance migratory shorebird population

BackgroundThe migratory process in birds consists of alternating periods of flight and fueling. Individuals of some populations make few flights and long stopovers, while others make multiple flights between short stopovers. Shorebirds are known for executing marathon flights (jumps), but most populations studied are long distance migrants, often crossing major barriers and thus forced to make long-haul flights. The sub-division of migration in short/medium distance migratory populations, where the total migration distance is shorter than documented non-stop flight capacity and where routes offer more homogenous stopover landscape, is little explored.MethodsHere we combine data based on conventional light level geolocators and miniaturized multi sensor loggers, comprising acceleration and light sensors, to characterize the migratory routes and migration process for a short/medium distance (~ 1300 to 3000 km) migratory population of common ringed plover (Charadrius hiaticula) breeding in southern Sweden. We were specifically interested in the variation in number and duration (total and individual) of flights/stopovers between seasons and in relation to migration distance.ResultsMost stopovers were located along the European Atlantic coast. On average 4.5 flights were made during autumn migration irrespective of migration distance, but in spring the number of flights increased with distance. The equal number of flights in autumn was explained by that most individuals migrating farther performed one longer flight (all but one lasting > 20 h), likely including crossing of the Bay of Biscay. Median duration of single flights was 8.7 h in autumn and 5.5 h in spring, and median stopover duration was ~ 1 day in both seasons. There was a positive relationship between total flight duration and migration distance, but total flight duration was 36% lower in spring compared to autumn.ConclusionsOur results suggest that when suitable stopovers are abundant common ringed plovers prefer making shorter flights even if longer flights are within the capacity of the species. This behaviour is predicted under both time and energy minimizing strategies, although the variable flight distances suggest a policy of time selected migration. Even if populations using several stopovers seem to be more resilient for environmental change along the route, these results are informative for conservation efforts and for predicting responses to future environmental change.

Evaluating the theoretical performance of aircraft wastewater monitoring as a tool for SARS-CoV-2 surveillance.

Air travel plays an important role in the cross-border spread of infectious diseases. During the SARS-CoV-2 pandemic many countries introduced strict border testing protocols to monitor the incursion of the virus. However, high implementation costs and significant inconvenience to passengers have led public health authorities to consider alternative methods of disease surveillance at borders. Aircraft wastewater monitoring has been proposed as one such alternative. In this paper we assess the theoretical limits of aircraft wastewater monitoring and compare its performance to post-arrival border screening approaches. Using an infectious disease model, we simulate an unmitigated SARS-CoV-2 epidemic originating in a seed country and spreading to the United Kingdom (UK) through daily flights. We use a probabilistic approach to estimate the time of first detection in the UK in aircraft wastewater and respiratory swab screening. Across a broad range of model parameters, our analysis indicates that the median time between the first incursion and detection in wastewater would be approximately 17 days (IQR: 7-28 days), resulting in a median of 25 cumulative cases (IQR: 6-84 cases) in the UK at the point of detection. Comparisons to respiratory swab screening suggest that aircraft wastewater monitoring is as effective as random screening of 20% of passengers at the border, using a test with 95% sensitivity. For testing regimes with sensitivity of 85% or less, the required coverage to outperform wastewater monitoring increases to 30%. Analysis of other model parameters suggests that wastewater monitoring is most effective when used on long-haul flights where probability of defecation is above 30%, and when the target pathogen has high faecal shedding rates and reasonable detectability in wastewater. These results demonstrate the potential use cases of aircraft wastewater monitoring and its utility in a wider system of public health surveillance.

Survey of the flight efficiency of a long-haul aircraft under uncertainty of tasks

The article considers the problem of optimizing a long-haul aircraft flight under uncertainty of objectives and tasks. Based on the analysis of the well-known flight mode selection criterion, two main objectives of the flight were identified minimizing fuel consumption and flight endurance. The study of this criterion based on a multi-purpose approach made it possible to develop an analytical model of the performance indicator containing two objective functions and a weight coefficient as a measure of comparative importance between the identified objectives. It is shown that the weight coefficient in the tasks of flight efficiency research is a measure of the uncertainty of the tasks. Consideration of the weight coefficient role in the optimization problem objective function made it possible to develop operational and trajectory methods for selecting flight modes. In the developed statement of the problem, the problems of cruise flight optimization and climb and descent modes are considered. The paper introduces the concept of the optimal cruise range as a vertical separation criterion, which allows you to rationally design the flight path at different flight levels under the uncertainty of tasks. The procedure for researching the efficiency and optimization of flight has been conducted and demonstrated by the method of mathematical modeling. The results of optimizing the flight mode are compared with the typical flight modes recommended by the flight manual. The introduced methods of flight efficiency investigation can be helpful in developing recommendations of long-haul aircraft operation. The methods and principles of a multi-purpose approach, operations research and decision theory were used in the paper. The long-haul aircraft IL-96-300 was selected as the object of research.

Implications of preferential access to land and clean energy for Sustainable Aviation Fuels

Aviation is highly dependent on liquid fossil fuel, and the production of ‘sustainable aviation fuels’ (SAF) is being proposed as a solution to removing the fossil carbon component, especially for long-haul flights. An analysis of 12 aviation roadmaps for net zero 2050 reveals heavy reliance on biogenic SAF in the medium-term and synthetic e-kerosene in the longer term. Realising these roadmaps could require 9 % of global renewable electricity and 30 % of sustainably available biomass in 2050, with significant energy ‘losses’. The continued use of hydrocarbon fuel in the roadmaps generates 1.35 GtCO2 in 2050, of which 30 % are still from fossil fuel. The net carbon savings from the 70 % depend on the direct and indirect life cycle emissions of producing SAF. Additional effects that are omitted in most roadmaps relate to decadal time lags in re-sequestering biocarbon in the case of forest biomass and the impact of non-CO2 emissions. Both require greater scrutiny in fully understanding the climate impact of SAF substitution. The scaling up of SAF to not only maintain but grow global aviation is problematic as it competes for land needed for nature-based carbon removal, clean energy that could more effectively decarbonise other sectors, and captured CO2 to be stored permanently. As such, SAF production undermines global goals of limiting warming to 1.5 °C; a conflict that is neither recognised in the roadmaps nor in the public debate.

Elite athletes’ and support staffs’ experiences and perceptions of long-haul travel, and the self-management strategies they use

Elite athletes and their support staff are often required to travel for international competitions all over the globe, however little is known about their experiences of long-haul (LH) travel and its perceived effects on performance. The aim of this study was to explore elite athletes’ and support staffs’ perception of symptoms experienced following LH travel and the self-management strategies they used to mitigate these symptoms. Elite athletes and support staff ( n = 88), who had embarked on an LH flight (> 8 hours) in the previous 2 years for training or competition, completed a survey examining their perceptions of LH travel, symptoms experienced following the flight(s) and strategies they implemented to minimise the symptoms. Associations between symptoms experienced and travel strategies used with participant and journey characteristics were examined by Chi-squared tests. LH travel was widely perceived by participants to be disruptive to physical (86.4%) and mental performance (72.7%) and to increase the risk of illness and injury (86.4%). The most common symptoms experienced were related to fatigue and disruption to sleep. All participants implemented strategies to help mitigate the negative consequences of LH travel. Moving and stretching regularly in-flight and simple strategies for aligning the body clock to destination time were most prevalent. The study findings will allow the translation of research to better inform future guidelines that address the unique needs and priorities of elite athletes and support staff as they embark on LH travel for training and competition with a view to optimising performance outcomes.

Autonomous Recharging and Flight Mission Planning for Battery-Operated Autonomous Drones

Unmanned aerial vehicles (UAVs), commonly known as drones, are being increasingly deployed throughout the globe as a means to streamline monitoring, inspection, mapping, and logistic routines. When dispatched on autonomous missions, drones require an intelligent decision-making system for trajectory planning and tour optimization. Given the limited capacity of their onboard batteries, a key design challenge is to ensure the underlying algorithms can efficiently optimize the mission objectives along with recharging operations during long-haul flights. With this in view, the present work undertakes a comprehensive study on automated tour management systems for an energy-constrained drone: (1) We construct a machine learning model that estimates the energy expenditure of typical multi-rotor drones while accounting for real-world aspects and extrinsic meteorological factors. (2) Leveraging this model, the joint program of flight mission planning and recharging optimization is formulated as a multi-criteria Asymmetric Traveling Salesman Problem (ATSP), wherein a drone seeks for the time-optimal energy-feasible tour that visits all the target sites and refuels whenever necessary. (3) We devise an efficient approximation algorithm with provable worst-case performance guarantees and implement it in a drone management system, which supports real-time flight path tracking and re- computation in dynamic environments. (4) The effectiveness and practicality of the proposed approach are validated through extensive numerical simulations as well as real-world experiments. Note to Practitioners—This study is stimulated by the need for developing pragmatic and provably efficient automated tour management systems for UAVs deployed on energy-constrained, long-distance flight missions. As such, UAVs provide a nifty platform for facilitating environmental monitoring, disaster management, transport of medical supplies, as well as expediting last-mile deliveries. However, existing path planners generally fall short of capturing several crucial aspects, such as detailed power consumption model (e.g., factoring in payload, wind speed and direction) or performance guarantees, potentially leading to underutilized or infeasible routing decisions. To address these issues, the present work proposes a theoretically-backed routing approach with a certifiable degree of optimality and develops an effective, practical power consumption evaluation model for multi-rotor UAVs, verified on multiple drone models.

Evaluation of infection probability of Covid-19 in different types of airliner cabins.

According to the World Health Organization (https://covid19.who.int/), more than 651 million people have been infected by COVID-19, and more than 6.6 million of them have died. COVID-19 has spread to almost every country in the world because of air travel. Cases of COVID-19 transmission from an index patient to fellow passengers in commercial airplanes have been widely reported. This investigation used computational fluid dynamics (CFD) to simulate airflow and COVID-19 virus (SARS-CoV-2) transport in a variety of airliner cabins. The cabins studied were economy-class with 2-2, 3-3, 2-3-2, and 3-3-3 seat configurations, respectively. The CFD results were validated by using experimental data from a seven-row cabin mockup with a 3-3 seat configuration. This study used the Wells-Riley model to estimate the probability of infection with SARS-CoV-2. The results show that CFD can predict airflow and virus transmission with acceptable accuracy. With an assumed flight time of 4h, the infection probability was almost the same among the different cabins, except that the 3-3-3 configuration had a lower risk because of its airflow pattern. Flying time was the most important parameter for causing the infection, while cabin type also played a role. Without mask wearing by the passengers and the index patient, the infection probability could be 8% for a 10-h, long-haul flight, such as a twin-aisle air cabin with 3-3-3 seat configuration.

Design and route optimisation for an airship with onboard solar energy harvesting

ABSTRACT Based on commercial passenger-carrying airships like LZ129 or R100, a hypothetical electric rigid framed airship including a solar cell covered surface and a lithium-ion battery is designed. The size of the battery and the coverage with solar cells are selected such that long-haul flights are possible. To simulate flight times, weather data from 2019 and time-dependent solar irradiation are used. Travel route and battery use are optimised in order to reduce flight times. For a mid-range and long-haul use case for passenger or freight transport, travel times have been calculated. Building on these results, analysis of CO2 emissions, land-use, and operating costs are carried out to reveal that depending on the use case, CO2 emissions of solar-powered airships could be as low as 1% to 5% of the emissions of a conventional aircraft at an estimated energy consumption in USD per km of 0.5% to 2.5%.

A Comprehensive Review of Risk Factors for Venous Thromboembolism: From Epidemiology to Pathophysiology

Venous thromboembolism (VTE) is the third most common cause of death worldwide. The incidence of VTE varies according to different countries, ranging from 1-2 per 1000 person-years in Western Countries, while it is lower in Eastern Countries (<1 per 1000 person-years). Many risk factors have been identified in patients developing VTE, but the relative contribution of each risk factor to thrombotic risk, as well as pathogenetic mechanisms, have not been fully described. Herewith, we provide a comprehensive review of the most common risk factors for VTE, including male sex, diabetes, obesity, smoking, Factor V Leiden, Prothrombin G20210A Gene Mutation, Plasminogen Activator Inhibitor-1, oral contraceptives and hormonal replacement, long-haul flight, residual venous thrombosis, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, trauma and fractures, pregnancy, immobilization, antiphospholipid syndrome, surgery and cancer. Regarding the latter, the incidence of VTE seems highest in pancreatic, liver and non-small cells lung cancer (>70 per 1000 person-years) and lowest in breast, melanoma and prostate cancer (<20 per 1000 person-years). In this comprehensive review, we summarized the prevalence of different risk factors for VTE and the potential molecular mechanisms/pathogenetic mediators leading to VTE.

A Numerical Study of the Suitability of Phase-Change Materials for Battery Thermal Management in Flight Applications

Battery pack specific energy, which can be enhanced by minimising the mass of the battery thermal management system (BTMS), is a limit on electric fixed-wing flight applications. In this paper, the use of phase-change materials (PCMs) for BTMSs is numerically explored in the 3D domain, including an equivalent circuit battery model. A parametric study of PCM properties for effective thermal management is conducted for a typical one-hour flight. PCMs maintain an ideal operating temperature (288.15 K–308.15 K) throughout the entire battery pack. The PCM absorbs heat generated during takeoff, which is subsequently used to maintain cell temperature during the cruise phase of flight. In the control case (no BTMS), battery pack temperatures fall below the ideal operating range. We conduct a parametric study highlighting the insignificance of PCM thermal conductivity on BTMS performance, with negligible enhancement observed across the tested window (0.1–10 W m−1 K−1). However, the PCM’s latent heat of fusion is critical. Developers of PCMs for battery-powered flight must focus on enhanced latent heat of fusion, regardless of the adverse effect on thermal conductivity. In long-haul flight, an elongated cruise phase and higher altitude exasperate this problem. The unique characteristics of PCM offer a passive low-mass solution that merits further investigation for flight applications.

Detached Retina on a Cataract Surgery Patient After Long-Haul Flights

Because of change, the pressure in a cabin in an airplane and the potential eye problem can be caused. The ophthalmologist determined that patients who had undergone cataract surgery or vitreoretinal surgery on long-haul flights should be informed for clarification. Neuro-ocular vestibular dysfunction (NOVD), ischemic optic neuropathy, exacerbating diabetic macular edema have also been reported in association with the disorder eye occurred while on a plane. The International Headache Society (IHS) has classified eye pain that occurs while traveling by plane as a headache type since 2013. In this paper, we reported a patient who received cataract surgery (lens extraction / intraocular lens IOL) without any complications having a postoperative vision of 6/6, 6 months prior, when performing a flight for more than 20 hours his eye was diagnosed a retinal detachment with blind vision and restored vision after one month of treatment.

The radiation environment over the African continent at aviation altitudes: first results of the RPiRENA-based dosimeter

The radiation environment over the African continent, at aviation altitudes, remains mostly uncharacterized and unregulated. In this paper, we present initial measurements made by a newly developed active dosimeter onboard long-haul flights between South Africa and Germany. Based on these initial tests, we believe that this low-cost and open-source dosimeter is suitable for continued operation over the African continent and can provide valuable long-term measurements to test dosimetric models and inform aviation policy.

Barriers in the diagnosis of pulmonary embolism

11 years ago, I fainted in São Paulo International Airport after landing from a long-haul flight. I was unconscious for about 3 min, had a heart rate of 130 beats per min, normal blood glucose, and oxygen saturation of 93%. I was attended by the emergency medical service of the airport, but no measure was taken. As I recovered consciousness and walked to the exit, I had breathlessness and a real sense of death. Upon noticing the urgency of the situation, a woman called the emergency medical service again, and I was attended by two female medical doctors.

Climate-Optimised Intermediate Stop Operations: Mitigation Potential and Differences from Fuel-Optimised Configuration

Saving fuel by splitting a flight mission with an intermediate stop for refuelling is described by the concept of intermediate stop operations. This can also be beneficial to the climate impact of aviation, if the flight level and intermediate stop airport are selected accordingly. This study aims to estimate the mitigation potential of an implementation of climate-optimised intermediate stop operations for European long-haul flights and compare it to fuel-optimal operations. For this purpose, fuel consumption and emissions are simulated along four-dimensional trajectories for the selected annual flight plan, and their average temperature response is calculated. A comparison between the reference case and climate-optimised as well as fuel-optimised scenarios shows a significant climate mitigation potential and reveals a shift of trajectories to lower latitudes and altitudes. However, increased flight times and fuel consumption limit implementation from stakeholders’ perspectives.

Aeropropulsive assessment of engine installation at cruise for UHBPR turbofan with body force fan modelling

The overall propulsive performance of an aircraft with podded nacelles depends on the interaction occurring between the wing body and the propulsor. With the tight installation required for Ultra-High Bypass Ratio (UHBPR) turbofans, the engine and airframe flows are more coupled, resulting in a mutual interference that can affect the working condition of the turbomachinery and the wing flow. In the paper, we employ a fully coupled fan stage model based on a body force method to evaluate the performance of an ultra-high bypass ratio turbofan in a nominal and closely-coupled installation position, along the cruise phase of a long-haul flight at Mach number 0.85. By comparing the results obtained with a standard powered-on representation based on one-dimensional static boundary conditions, we assess the effect of the engine/airframe coupling on the aerodynamics and propulsive forces. The major differences occur on the discharge flow, on the internal fan nozzle duct and on the jet/wing interaction, due to the nonuniform fan stage outlet status in the body force simulations. The net vehicle force deviates from 1% to 1.6%, according to the position and the cruise phase. The sensitivity of the propulsive forces to the change of installation position, instead, is in general consistent for the two methods. The discrepancy can be much larger if the 1D boundary conditions are not corrected for true engine operating points arising under installation, exceeding 8% in the tighter assembly for the net vehicle force.