Long-haul Air Research Articles

Performance sensitivity of subsonic liquid hydrogen long-range tube-wing aircraft to technology developments

Liquid hydrogen (LH2) may enable the decarbonisation of long-haul aviation. However, its low volumetric energy density and subsequent tank space and weight requirements could penalise an aircraft's specific energy consumption (SEC, MJ/tonne-km). We evaluate the impacts of developments in four technology areas – aerodynamics, structures, cryo-tank gravimetric index (η), and overall efficiency (ηo) – on the design-point performance of a large subsonic tube-wing LH2 aircraft. We characterise the critical value of η, which must be exceeded to enable a given design range. For a design range of 14,000 km, η must exceed 0.52 today but only 0.35 with expected 2030 airframe and engine efficiency improvements. Using the most optimistic technology development estimates we observe that SEC could reduce by ∼25% via improvements in ηo and aerodynamics and by 33% via improvements in all four areas. Developments in technologies to improve ηo and reduce drag are critical to enabling zero-carbon long-haul air travel.

Stopovers as valued-based experience: A conceptual model

This study on stopovers, defined as consisting of a one to three-night transition to a destination featuring value-based experiences, uses a multi-site data collection approach of focus groups in six cities to examine stopovers during long-haul air travel in Dubai and Abu Dhabi, Singapore and Hong Kong. It contributes to the literature on stopovers by defining and conceptualizing the term and identifying the key influences of stopover choice and value experiences of travelers from distant geographic areas, namely, the United Kingdom, France, Australia, and New Zealand. The proposal of the conceptual model on stopovers offers a basis for destination marketers a greater understanding of stopover travelers and facilitates the destination's promotion from a practical perspective.

Airline company's resource reallocation using network centralized data envelopment analysis with slack-based measure

PurposeSince airlines that employ their resources effectively will achieve operating profitability, air route resource allocation is significant for airlines. This study aims to investigate an appropriate model to reallocate resources into each air route of an airline company.Design/methodology/approachThis study proposes a network centralized data envelopment analysis (DEA) models with slack-based measure (SBM). The proposed model not only takes into account the two interconnected stages but also considers the nonradial approach with transfer-in and transfer-out slacks for resource reallocating. Furthermore, the authors modify the objective function to an input-oriented function with SBM, and divide the model into passenger and freight parts, which makes the model more realistic for the characteristic of air routes.FindingsThe empirical analysis using an airline company's internal data provides airline operators with information on how they increase or decrease input resources, which can serve as a practical guideline of resource reallocation. Specifically, the results indicate that the airline company should increase their input resources into long-haul air routes such as KOR-OCN while decreasing their input resources into short-haul air routes such as Korean-Oceania (KOR-OCN), Korean-Chinese (KOR-CHN), Korean-Southeast Asian (KOR-SEA), Korean-Japanese (KOR-JPN).Originality/valueAlthough some papers evaluate air route efficiencies based on the DEA approach, a few existing papers have addressed resource allocation for air routes. This paper is the first to study the resource reallocation for air routes based on the DEA approach, contributing to the literature in expanding the scope of research on resource reallocation.

Symposium: perspectives on carbon taxes – introduction

With this issue of Fiscal Studies, we inaugurate a new section entitled ‘Symposia’. This new section will publish commissioned papers from leading scholars and policy analysts on issues of topical importance to public economics and microeconomic policy. In some cases these symposia will emphasise policy issues, while in other cases contributions will emphasise methodological issues, and sometimes both. Over the course of future symposia, papers will be more diverse in format and content than traditional research papers. A common thread running through the papers will be perspectives guided by rigorous research evidence, but with the aim of reaching a broad audience across the research, policy and stakeholder communities. In this inaugural issue we focus on global climate change, and in particular on policies and practices to tax carbon emissions within and across borders. Economists have, in general, been highly supportive of carbon-based taxation as a mechanism to efficiently reduce greenhouse gas emissions. However, the implementation of such a tax is challenging when spillover effects across state and national borders are considered. The first paper in the symposium, which is by Michael Keen of the University of Tokyo along with Ian Parry and James Roaf of the International Monetary Fund, examines the design, rationale and potential impact of a border carbon adjustment. The fundamental concern of unilateral action on carbon pricing is that others will free ride on the policy, thus potentially harming domestic producers and consumers vis-à-vis trading partners. The authors propose a border carbon adjustment that assesses a charge (either direct taxation or tradable pollution permits) on the carbon content of imported products. The intent is that the charge will be equivalent to domestic carbon pricing, and with the option of rebates for the carbon content of exports. The paper first spells out the theoretical and practical motivations for a border carbon adjustment and then proposes a series of design options to provide guidance to policymakers. The second paper in the symposium, which is by Stuart Adam, Isaac Delestre, Peter Levell and Helen Miller, all of the Institute for Fiscal Studies, documents the patchwork of current tax and subsidy programmes that aim to mitigate greenhouse gas emissions in the United Kingdom, and examines how these have created oftentimes conflicting incentives and distortions for households and firms to reduce their carbon emissions. The authors calculate implied carbon taxes levied by source and user of energy and show, for instance, that businesses are taxed more heavily than households, but that energy-intensive industries face lower carbon tax rates than other businesses; emissions from long-haul air travel are lightly taxed when compared with those from short-haul air travel, and for those flying first class the implied carbon tax rate is still lower. On this, the UK is not exceptional; rather, inconsistencies in the taxation of carbon emissions across different sources and users are common to many countries. In some cases, governments may find it desirable to deviate from a uniform carbon tax rate. The authors show that distributional considerations and other concerns may help justify some, but not all, of the variation in carbon prices, and argue for the rationalisation of carbon taxation. The papers in this first symposium highlight some of the challenges facing nations as they grapple with the most pressing and far-reaching economic challenge of our time. It is our hope that the papers in the issue, and in future symposia, will not only spur additional research, but will also make a meaningful and timely contribution to the public discussion of key topical issues, and serve as a platform to inform policymakers of best practices and policies based on the evidence.

The non-sovereign territories: Economic and environmental challenges of sectoral and geographic over-specialisation in tourism and financial services

This paper analyses the economic and geographic characteristics of the world’s principal non-sovereign territories in the context of the growth challenges facing small economies. These territories enjoy high degrees of policy autonomy within a complex array of relationships with their metropolitan countries. Seven of the ten metropolitan powers are European and account for 38 of the 49 inhabited non-sovereign territories. The territories’ distinct economic and geographic characteristics, notably small size and remoteness, have led to their adopting similar niche sectoral growth strategies to those of small sovereign states and a reliance upon tourism and financial services. In spite of the growth challenges faced, most of these territories have attained high levels of per capita gross national income, placing them in the World Bank High Income category. Global heating, economic crises and regional environmental shocks, along with growing international protectionist sentiments, however, raise critical questions regarding the continued viability of their traditional growth strategies, particularly their heavy reliance upon environmentally harmful long-haul air travel and cruise tourism. This paper bridges the gap between large-scale growth studies, which generally overlook non-sovereign entities, and single case studies to examine the determinants of the growth success of non-sovereign territories and their future growth challenges given the pressing need for both economic and environmental sustainability.

Analysing and modeling performances of a long-haul air route network

This paper deals with analyzing and modelling performances of a long-haul air route network operating as the queuing network. The network consists of the routes/tracks with flight levels serving aircraft/flights as the service channels. The main network performances are the ultimate and practical capacity of service channels, the aircraft/flight demand, delays before entering and total time of aircraft/flights spending in the network, and the related generalized costs including those of airlines, air passengers, policy makers and society. The analytical models of the particular network performances and three routing or assignment models/procedures for matching the aircraft/flight demand to capacity are developed and applied to the long-haul air route network in the North Atlantic airspace between Europe and North America.
 The results have indicated that. the network capacity has been strongly dependent on the number of routes/tracks and flight levels, i.e., service channels and their ultimate and/or practical capacity. The ultimate capacity has been mainly influenced by the ATC (Air Traffic Control) separation rules applied between aircraft/flights operating in the same directions. The practical capacity has been strongly influenced by the ultimate capacity and the average delays imposed on aircraft/flights before entering the network. The rather superior and close to optimal model/procedure for matching demand to capacity has been routing or assignment of the aircraft/flights demand in proportion to the ultimate or practical capacity of particular service channels minimizing the total generalized costs of the actors/stakeholders involved.

Oxygenation pattern and compensatory responses to hypoxia and hypercapnia following bilateral carotid body resection in humans.

Five years after bilateral carotid body resection (bCBR) performed in four patients, the absence of the hypoxic ventilatory response persisted, suggesting no compensatory regrowth. Breathing hypoxic gas mixtures (15% and 12%) results in a lower (by ∼10%) minimal blood oxygen saturation ( ) in bCBR patients compared to heart failure subjects (CHF) with intact peripheral chemoreceptors. After bCBR, patients were characterized by a greater short-term variability in during mild hypoxia in comparison to the CHF group. The ventilatory response to hypercapnia was preserved following bCBR and was sufficient to maintain minimal at levels comparable to controls when combined with hypoxia. Bilateral CBR - a novel treatment modality for sympathetically mediated diseases - should be used with caution due to the risk of significant desaturation even during mild hypoxia equivalent to that experienced during long-haul air travel and high altitude. Carotid body resection has been proposed as a novel treatment for sympathetically mediated diseases but the safety of bilateral carotid body resection (bCBR) for blood oxygenation during hypoxic stress (long-haul flights or high altitude) remains uncertain. Also unknown is whether central ventilatory drive is sufficient to maintain adequate oxygen saturation when exposed to hypercapnia with concomitant hypoxia. Thus, we administered: 15% O2 , 12% O2 , 5% CO2 /12% O2 and 5% CO2 /95% O2 to a group of four patients with congestive heart failure (65±2.9years) in whom bCBR was performed 5years earlier. Ventilatory, haemodynamic and blood oxygen saturation ( ) responses were recorded non-invasively and compared to control groups with intact peripheral chemoreceptors (both healthy and heart failure patients). First, we confirmed that the ventilatory response to hypoxia was eliminated in patients with bCBR, although the increase in cardiac output was preserved. Second, administration of hypoxic gas mixtures resulted in a larger decrease in and greater short-term variability of the leading to a lower minimal for both hypoxia levels in the bCBR group compared to heart failure controls (82.5±1.2% vs. 91.6±2.3% for 15% O2 and 73.8±4.0% vs. 83.7±3.1% for 12% O2 ). Third, in bCBR patients the ventilatory response to hypercapnia was present and sufficient to maintain a minimal at a level comparable to heart failure controls following administration of 5% CO2 /12% O2 (88.7±4.2% vs. 91.1±2.8%). We conclude that bCBR carries a risk of significant oxygen desaturation even during mild hypoxia. Despite preservation of central chemosensitivity, future studies should focus on unilateral CBR or on pharmacological modulation of peripheral chemosensitivity.

Changing concept of the long-haul air transportation market

Changing concept of the long-haul air transportation market

Implementation of a Long-Range Air Traffic Flow Management for the Asia-Pacific Region

We provide a concept of operations and a corresponding implementation of a long-range air traffic flow management in the Asia-Pacific region. This management will provide an appropriate demand-capacity balancing considering both aircraft sequencing by local arrival management procedures and flow optimization to prevent over-demand in the approach area around the airport. Thus, coordination of long-range international flights demands collaboration between different flight information regions and local regulations. As Singapore Changi Airport is a central element of the Asia-Pacific flow management high share of long-haul air traffic, we use this airport to demonstrate our approach. To derive the operational conditions and actual traffic patterns at the airport, ADS-B messages and flight plan information are processed. The data are cleaned, analyzed, and filtered to provide information about arrival flows within given distances to the airport. We provide an efficacy analysis of the long-range air traffic flow management using two approaches. First, we applied a mixed-integer optimization of time shifts of normal distributed flight times. Here, the regulation of long-range flights by time shifts (e.g., achieved by speed advisories) shows a significant relief from periods of over-demand at the airport approach sector. Second, we implement a reference and a test case scenario in an agent-based simulation environment including the local arrival management procedures. Here, the number of holdings and the associated holding time could be reduced by at least 26%.

Mapping causalities of airline dynamics in long-haul air transport markets

The introduction of low-cost air transport services to short-haul routes has significantly shaped the structure of this market segment. Recent research investigates and discusses the transferability of the low-cost carrier business model to long-haul routes and identifies respective challenges such as lower cost advantages over the competing full-service network business model. Our paper complements the existing research with a review of airline dynamics in long-haul air transport markets and the subsequent development of a causal loop diagram of the transatlantic air transport market using systems thinking. The objective of this paper is to provide an overview of specific characteristics regarding airline operations in the transatlantic air transport market to investigate the market potential of long-haul low-cost carriers competing with full-service network carriers in this market. We implement these characteristics in a causal loop diagram which comprises the most important elements of and causalities within the long-haul air transport market that affect the development of these elements. These include the generation of transatlantic air transport demand, passenger choice, and airline ticket price and fleet development. The causal loop diagram serves as a framework for qualitative investigation of the market potential of long-haul low-cost services. The paper proves systems thinking to be a feasible approach to map causalities based on knowledge from scientific literature.

Stopover destination attractiveness: A quasi-experimental approach

This study contributes to the emerging field of stopover destination attractiveness. There has been a paucity of published research around the phenomenon of stopovers, including stopover destination image, during long-haul international air travel. This is surprising given long-haul commercial flights date back to the 1930s, and that destination image has been the most popular topic in the tourism marketing literature since the 1970s. A quasi-experimental research design with samples of consumers in the UK and Australia was used to test aspects of a proposed model of stopover destination attractiveness. The results highlight the influence of perceived airport ambience and positive user-generated content on social media on enhancing attitudinal destination loyalty for Dubai as a stopover destination. The study also highlights the positive influence of previous visitation on attitudinal destination loyalty for a destination located in the Middle East, a region with a history of negative media publicity around conflicts. It is proposed these findings have practical implications for emerging stopover destinations, and for other destinations in conflict-ridden regions such as the Middle East. • A rare investigation into the phenomenon of stopovers during long haul international air travel. • A quasi-experimental research design to test a hypothesised model of stopover destination attractiveness for Dubai. • The results highlight the importance of the influence of perceived ambience and positive user-generated content on social media on enhancing attitudinal loyalty for Dubai as a stopover destination. • The study also highlights the positive influence of previous visitation on attitudinal destination loyalty for a destination located in the Middle East, a region with a history of negative media publicity around conflicts.

Sleep Hygiene and Light Exposure Can Improve Performance Following Long-Haul Air Travel.

To assess the efficacy of a combined light exposure and sleep hygiene intervention to improve team-sport performance following eastward long-haul transmeridian travel. Twenty physically trained males underwent testing at 09:00 and 17:00hours local time on 4 consecutive days at home (baseline) and the first 4 days following 21hours of air travel east across 8 time zones. In a randomized, matched-pairs design, participants traveled with (INT; n = 10) or without (CON; n = 10) a light exposure and sleep hygiene intervention. Performance was assessed via countermovement jump, 20-m sprint, T test, and Yo-Yo Intermittent Recovery Level 1 tests, together with perceptual measures of jet lag, fatigue, mood, and motivation. Sleep was measured using wrist activity monitors in conjunction with self-report diaries. Magnitude-based inference and standardized effect-size analysis indicated there was a very likely improvement in the mean change in countermovement jump peak power (effect size 1.10, ±0.55), and likely improvement in 5-m (0.54, ±0.67) and 20-m (0.74, ±0.71) sprint time in INT compared with CON across the 4 days posttravel. Sleep duration was most likely greater in INT both during travel (1.61, ±0.82) and across the 4 nights following travel (1.28, ±0.58) compared with CON. Finally, perceived mood and motivation were likely worse (0.73, ±0.88 and 0.63, ±0.87) across the 4 days posttravel in CON compared with INT. Combined light exposure and sleep hygiene improved speed and power but not intermittent-sprint performance up to 96hours following long-haul transmeridian travel. The reduction of sleep disruption during and following travel is a likely contributor to improved performance.

Effects of Westbound Trans-meridian Travel on Countermovement Jump Performance in International-Level Rowers.

Everett, KLA, Chapman, DW, Mitchell, JA, and Ball, N. Effects of westbound trans-meridian travel on countermovement jump performance in international-level rowers. J Strength Cond Res 36(7): 1961-1965, 2022-International long-haul air travel is a necessity for many athletes as part of their training or competition schedules. However, long-haul travel is also associated with impaired neuromuscular function. An athlete's lower body neuromuscular status is frequently assessed and monitored using countermovement jump (CMJ). This study assessed the impact of westbound trans-meridian travel on changes in CMJ performance in highly trained aerobic athletes. Highly trained male rowers (n = 21, 23.7 ± 1.4 years, 1.91 ± 0.07 m, 86.9 ± 9.9 kg) undertook a westbound flight incurring 22 hours of flight time with 30 hours of total travel time across 9 time zones. Athletes completed a single set of 6 loaded CMJ repetitions before and after travel with performance measured using a digital optical encoder attached to a 20 kg barbell. Each CMJ repetition was assessed for mean concentric velocity, jump height (JH), eccentric displacement, JH:dip ratio, mean power, and mean eccentric velocity, with comparisons made between mean set changes before and after travel. Changes were compared using a one tail paired t-test and characterized using Cohen's d (95% confidence interval) effect sizes. Significance was accepted at p ≤ 0.05. Small-to-moderate changes were observed in all variables following westbound travel. These changes may be because of retention of high training loads before travel resulting in the athletes being in a fatigued state, whereas travel time worked as a forced recovery period. Reductions in CMJ performance are likely following westbound travel, however, may be affected by training fatigue before travel that may confound CMJ performance as a monitoring metric.

The long-haul low-cost airline business model: A disruptive innovation perspective

This paper analyzes the impact of the long-haul low-cost (LHLC) airline business model on the air transport industry from a disruptive innovation perspective. We argue that the LHLC business model is set to stay; it is bound to penetrate the mass market that has, to date, been occupied by incumbent network carriers. It will thus lead to significant strategic adaptations in the long-haul air travel market where incumbents are well advised to prepare their responses. We provide a set of strategic response options along the categories of avoiding, accepting and embracing the LHLC business model that can be used by incumbents to defend their competitive positioning in the long-haul air travel market. This paper provides guidelines for airline managers to (re)evaluate the strategies of their own organizations facing the emergence of a potentially disruptive innovation in their industry.

Been there, done that: quasi-experimental evidence about how, why, and for who, a previous visit might increase stopover destination loyalty

ABSTRACT Despite stopovers being a part of long-haul air travel since commercial flights commenced over 80 years ago, the first published research on the phenomenon did not appear until 2016. Also, even though destination image has been the most researched construct in the destination marketing literature, no studies had measured perceptions of a destination in the context of a stopover until 2018. This study makes a contribution to this emerging research field by reporting how a quasi-experimental design found previous visitation enhances destination image and destination loyalty in the context of a stopover during long haul international air travel. However, this effect was weakened for individuals high in prevention focus. Conceptually, the research design is underpinned by Regulatory Focus Theory, which has rarely been reported in the destination marketing literature. The results have practical implications, for Dubai as a stopover destination, and for other destination marketing organizations responsible for emerging destinations or destinations in regions that have experienced negative publicity.

Modelling performance an air transport network operated by subsonic and supersonic aircraft

ABSTRACTThis paper deals with modelling the performance of an air transport network operated by existing subsonic and the prospective supersonic commercial aircraft. Analytical models of indicators of the infrastructural, technical/technological, operational, economic, environmental, and social performance of the network relevant for the main actors/stakeholders involved are developed. The models are applied to the given long-haul air route network exclusively operated by subsonic and supersonic aircraft according to the specified “what-if” scenarios.The results from application of the models indicate that supersonic flights powered by LH2 (Liquid Hydrogen) could be more feasible than their subsonic counterparts powered by Jet A fuel, in terms of about three times higher technical productivity, 46% smaller size of the required fleet given the frequency of a single flight per day, 20% lower sum of the aircraft/airline operational, air passenger time, and considered external costs, up to two times higher overall social-economic feasibility, and 94% greater savings in contribution to global warming and climate change. These flights could be less feasible in terms of about 70-85% higher aircraft/airline operational costs, 70% and 19% higher fuel consumption and emissions of Green House Gases, respectively, and 6-13% higher noise compared to the specified acceptable levels.

Door-to-door travel in 2035 – A Delphi study

Intermodal, door-to-door (D2D) travel is gaining momentum for airlines, airports, and feeder traffic providers. At the same time, competition is increasing; having a better understanding of future travelers’ requirements regarding D2D mobility is crucial for the mobility sector, for planning long-term, adapting products and services accordingly, and improving the overall passenger experience. Little information is available on this matter and gathering data in the future may be challenging. This paper considers future projections of European air passengers, and their requirements, for the entirety of the D2D travel chain, including long-haul air travel and airport access and egress modes. The research is based on a two-round Delphi survey (time horizon 2035) with 38 experts, incorporating panelists from the transport industry, academia, and consultants. The Delphi survey is supplemented with findings from a preliminary study, combining expert interviews (N = 18), a literature review, and an expert workshop. Based on the results from a hierarchical cluster analysis, the paper presents three possible future scenarios: (1) personalized D2D travel, (2) integrated D2D travel, and (3) the game changer.

Consumer surplus analysis of selected long-haul air transport routes connecting Germany with California and China

Measuring the impact of air transport on economic welfare is relevant for many policy decisions but also subject to controversial discussions among researchers. We propose the use of price elasticity estimates together with empirical data on passenger volumes and fare levels to derive air travel demand functions. The demand functions then allow a measurement of consumer surplus of passengers as a key economic benefit of air transport. More specifically, by using segment-specific market data on passenger volumes, fare levels and aggregated own-price elasticities, we calculate revenues and consumer surplus associated with directional nonstop origin-destination traffic on selected long-haul routes from and to Germany's largest airport Frankfurt.

Case Report: Unprovoked venous thromboembolism in a young adult

A 24-year-old male was presented to us with sudden onset of chest pain and dyspnea for the past one hour. There was no history of calf pain, trauma, surgery, prolonged immobilization, long-haul air travel, bleeding diathesis or any other co-morbidity. The patient denied any addiction history. The Electrocardiogram showed tachycardia with S1Q3T3 pattern. The left arterio-venous Doppler study was suggestive of a thrombus in popliteal vein and sapheno-popliteal junction. The CT-Pulmonary Angiogram scan was suggestive of a massive pulmonary thromboembolism. The patient was thrombolysed with Intravenous Alteplase immediately and was put on tab Rivaroxaban for maintenance. He was later discharged after being stable. Unprovoked venous thromboembolism (VTE) is very rare and has the potential to lead to pulmonary embolism which could be disastrous, especially in young adults. We present such a case where unprovoked VTE was diagnosed and treated. This case suggests that high clinical suspicion is the key for the diagnosis of acute pulmonary embolism, especially in the absence of history suggestive of deep vein thrombosis.

Effects of Sports Compression Socks on Performance, Physiological, and Hematological Alterations After Long-Haul Air Travel in Elite Female Volleyballers.

Broatch, JR, Bishop, DJ, Zadow, EK, and Halson, S. Effects of sports compression socks on performance, physiological, and hematological alterations after long-haul air travel in elite female volleyballers. J Strength Cond Res 33(2): 492-501, 2019-The purpose of this investigation was to assess the merit of sports compression socks in minimizing travel-induced performance, physiological, and hematological alterations in elite female volleyball athletes. Twelve elite female volleyballers (age, 25 ± 2 years) traveled from Canberra (Australia) to Manila (Philippines), and were assigned to 1 of 2 conditions; compression socks (COMP, n = 6) worn during travel or a passive control (CON, n = 6). Dependent measures included countermovement jump (CMJ) performance, subjective ratings of well-being, cardiovascular function, calf girth, and markers of blood clotting, collected before (-24 hours, CMJ; -12 hours, all measures), during (+6.5 and +9 hours, subjective ratings and cardiovascular function), and after (+12 hours, all measures except CMJ; +24 hours and +48 hours, CMJ) travel. When compared with CON, small-to-large effects were observed for COMP to improve heart rate (+9 hours), oxygen saturation (+6.5 hours and +9 hours), alertness (+6.5 hours), fatigue (+6.5 hours), muscle soreness (+6.5 hours and +9 hours), and overall health (+6.5 hours) during travel. After travel, small-to-moderate effects were observed for COMP to improve systolic blood pressure (+12 hours), right calf girth (+12 hours), CMJ height (+24 hours), mean velocity (+24 hours), and relative power (+48 hours), compared with CON. COMP had no effect on the markers of blood clotting. This study suggests that compression socks are beneficial in combating the stressors imposed by long-haul travel in elite athletes, and may have merit for individuals frequenting long-haul travel or competing soon after flying.