Eastbound Flights Research Articles

Profitability of supersonic travel

Since the retirement of the Concorde in 2003 no commercial supersonic flights were operated. In 2014 the aircraft manufacturing start-up Boom announced the development of a supersonic aircraft by 2029 and has since gathered 130 orders. This paper analyzes the profitability of this aircraft by calculating the net present value of an investment decision and comparing this to a subsonic aircraft. It is determined that supersonic travel has 50% higher cash operating costs per seat. This implies that, for example, a return flight LHR-JFK merely breaks even at a WACC of 6%. The central question of this paper is whether this cost premium can be covered by a price premium paid for the time saved on a supersonic flight. A schedule analysis shows that this price premium is justified on westbound but not on eastbound flights. Thus, a westward rotation of the supersonic fleet is proposed. To avoid seat imbalances this network can be supplemented by an eastward rotating subsonic narrowbody fleet in an all-business configuration. Whereas a supersonic rotation A - B - A only breaks even with a net present value close to zero, a westward supersonic rotation A - B - C - A complemented by a subsonic rotation A - C - B - A achieves a significant profit reflected in a net present value of over $ 40 mill. per aircraft. It follows that this network structure is the only profitable one.As a by-product it is reconstructed that the Concorde was marginally cash-positive, explaining why operations was kept up for 27 years but no aircraft were ordered after the initial batch.

Prevention and control of jet lag symptoms and temporary impairment of cognitive function with Pycnogenol® in healthy individuals and in hypertensives.

The aim of this registry study was to evaluate the efficacy of Pycnogenol® in controlling signs/symptoms and temporary impairment of cognitive function (COFU) associated with jet lag. Previous flight studies have shown a decrease in the level of jet lag symptoms with Pycnogenol®. The control of jet lag signs/symptoms appeared to be correlated with flight-related microangiopathy and peripheral edema. Pycnogenol® - a standardized extract from the bark of French maritime pine - has significant antiedema, anti-inflammatory and antioxidant properties. A group of subjects flying east in economy class for 10-12 hours used Pycnogenol® 150 mg/day and a similar group without supplementation served as controls. A subgroup of mild hypertensive subjects using a single ACE inhibitor was also included. One hundred twenty-seven subjects completed the study. Of the participants, 48 were aviation professionals like pilots, flight attendants or air company staff - 24 of them took Pycnogenol® and 24 served as controls. Forty-seven study participants were frequent flyers and non-staff professionals, 25 of which took Pycnogenol® and 22 served as controls. In addition, a group of 32 subjects with mild hypertension was included, 16 took Pycnogenol® and 16 served as controls. No side effects and a good tolerability were observed. The registry groups were comparable for baseline characteristics. Eastbound flights' duration was 11.22±0.4 hours in supplemented subjects and 11.14±0.32 in controls. Dropouts were due to logistical problems. Post flight Visual Analogue Scale (VAS) scores were significantly lower in all Pycnogenol® groups, including hypertensives for all signs and symptoms of jet lag compared to controls, showing prevention and improvement of jet lag symptoms. The duration of any sign/symptom of jet lag with Pycnogenol® intake was significantly shorter (P<0.05) post-flight compared to controls (P<0.05). The number of nights of altered/disturbed sleep was also lower in the Pycnogenol® groups compared to controls. Leg edema was present in almost all subjects with different degrees especially in the hypertensive group. The increase in ankle circumference before and after flight was significantly lower with Pycnogenol® compared to controls (P<0.05). After the flight, average scores of the single COFU tasks were significantly higher in the Pycnogenol® groups compared to controls, showing preserved cognitive function. In conclusion, in this registry study Pycnogenol® was effective in preventing jet lag-related symptoms and preserving cognitive functions without tolerability problems. These observations should be tested in a larger group of subjects including complex individuals prone to edema (i.e. diabetics, hypertensive or older patients).

Impact of climate variabilities on trans-oceanic flight times and emissions during strong NAO and ENSO phases

This study investigates the impact of the North Atlantic Oscillation (NAO) and El Niño Southern Oscillation (ENSO) on trans-oceanic round-trip flight times and consequent CO2 emissions over the north Atlantic and eastern Pacific regions. For three strongest winter periods of both polarity during 1979–2016, daily mean wind data are used to compute the wind-optimal flight trajectories at cruising altitudes. Results show that intensified upper-level jet streams during the +NAO winters provide stronger headwinds for westbound flights between the eastern US and the western Europe. This causes 4.24 ∼ 9.35 min increase in an averaged total round-trip journey time during the +NAO compared to −NAO winters. In the eastern Pacific region, the jet stream is extended eastward towards the southwestern US during the +ENSO period, which lengthens the travel time for westbound flights between Hawaii and the west coast of the US. The increase in travel time of westbound flights is greater than the corresponding decrease in travel time for eastbound flights, resulting in a 5.92 ∼ 8.73 min increase of the averaged total round-trip time during the +ENSO compared to the −ENSO periods. Extrapolating these results to overall trans-oceanic air traffic suggests that aircraft will take a total of 1908 ∼ 4207 (888 ∼ 1309) extra hours during the +NAO (+ENSO) than the −NAO (–ENSO) winters over the North Atlantic (Eastern Pacific) regions, requiring 6.9 ∼ 15 (3.2 ∼ 4.7) million US gallons of extra fuel burned at a cost of 21 ∼ 45 (9.6 ∼ 14) million US dollars and 66 ∼ 144 (31 ∼ 45) million kg of extra CO2 emissions to all trans-oceanic traffic. In +ENSO and +NAO winters, the chances of a given flight having a slower round-trip flight time with more fuel burn and CO2 emissions are 2–10 times higher than in a −ENSO or −NAO winter. These results have significant implications for the planning of long-term flight routes with climate variability.

A decentralized approach to formation flight routing of long-haul commercial flights

This paper describes the development of an optimization-based cooperative planning system for the efficient routing and scheduling of extended flight formations. This study considers the use of formation flight as a means to reduce the overall fuel consumption in long-haul airline operations. It elaborates on the operational implementation of formation flight, particularly focusing on the formation flight routing. A completely decentralized approach is presented, in the sense that formation flight is not planned pre-flight and is not subjected to any predefined routing restrictions. A greedy communication scheme is defined through which all participating aircraft are allowed to communicate with neighboring aircraft in order to establish flight formations in flight. A constraint on the formation-flight-induced additional flight time is introduced in order to suppress the occurrence of large detours in the assembly of flight formations. A transatlantic case study is presented that considers 347 eastbound flights. Assuming a 10% fuel flow reduction for any trailing aircraft in a formation, the overall network-wide fuel savings were estimated at 4.3% at the expense of an additional flight time of 10.3 min per flight on average. In this transatlantic long-haul scenario, a formation flight usage rate of 73% was realized.

The effect of flight distance on fuel mileage and CO2 per passenger kilometer

ABSTRACTIn this study, the effect of distance on fuel mileage (fuel burn per nautical mile) and CO2 intensity, based on a large amount of actual flight data, is discussed for narrow-body commercial aircraft performing domestic flights for flight distances of between ∼200 and ∼800 NM, in Turkey. For twenty-nine domestic routes, the average CO2 intensity is calculated to be 88 gr/pa-km, with an 80% load factor, ranging from between 112 gr/pa-km (207 gr/pa-NM) for the shortest route and 78 gr/pa-km (145 gr/pa-NM) for the longest route. An overall runway-to-runway analysis reveals that the average flight fuel consumption increases by 5.1 kg for each additional nautical mile. The discussion is extended to cover wind effect, through westbound and eastbound flights, on fuel consumption. The average fuel mileage of the eastbound flights, above 30 kft, is found to be 11.2% lower than those for the westbound flights. A sensitivity analysis is also carried out to reveal the effects of three main flight performance parameters, namely, cruise altitude, cruise speed and aircraft mass on the cruise CO2 intensity.

Transatlantic flight times and climate change

Aircraft do not fly through a vacuum, but through an atmosphere whose meteorological characteristics are changing because of global warming. The impacts of aviation on climate change have long been recognised, but the impacts of climate change on aviation have only recently begun to emerge. These impacts include intensified turbulence and increased take-off weight restrictions. Here we investigate the influence of climate change on flight routes and journey times. We feed synthetic atmospheric wind fields generated from climate model simulations into a routing algorithm of the type used operationally by flight planners. We focus on transatlantic flights between London and New York, and how they change when the atmospheric concentration of carbon dioxide is doubled. We find that a strengthening of the prevailing jet-stream winds causes eastbound flights to significantly shorten and westbound flights to significantly lengthen in all seasons. Eastbound and westbound crossings in winter become approximately twice as likely to take under 5 h 20 min and over 7 h 00 min, respectively. For reasons that are explained using a conceptual model, the eastbound shortening and westbound lengthening do not cancel out, causing round-trip journey times to increase. Even assuming no future growth in aviation, the extrapolation of our results to all transatlantic traffic suggests that aircraft will collectively be airborne for an extra 2000 h each year, burning an extra 7.2 million gallons of jet fuel at a cost of US$ 22 million, and emitting an extra 70 million kg of carbon dioxide, which is equivalent to the annual emissions of 7100 average British homes. Our results provide further evidence of the two-way interaction between aviation and climate change.

Reduction of the air traffic's contribution to climate change: A REACT4C case study

Air traffic alters the atmospheric composition and thereby contributes to climate change. Here we investigate the trans-Atlantic air traffic for one specific winter day and analyse, which routing changes were required to achieve a reduction in the air traffic's contribution to climate change. We have applied an atmosphere-chemistry model to calculate so-called five dimensional climate cost functions (CCF), which describe the climate effect of a locally confined emission. The five dimensions result from the emission location (3D), time (1D) and the type of emission (1D; carbon dioxide, water vapour, nitrogen oxides). In other words, carbon dioxide (CO2), water vapour (H2O) and nitrogen oxides (NOx) are emitted in amounts typical for aviation at many confined locations and times and their impacts on climate calculated with the atmosphere-chemistry model. The impact on climate results from direct effects, such as the changes in the concentration of the greenhouse gases CO2 and H2O and indirect effects such as contrail cirrus formation and chemical changes of ozone and methane by emissions of NOx. These climate cost functions are used by a flight planning tool to optimise flight routes with respect to their climate impact and economic costs of these routes. The results for this specific winter day show that large reductions in the air traffic’s contribution to climate warming (up to 60%) can be achieved for westbound flights and smaller reductions for eastbound flights (around 25%). Eastbound flights take advantage of the tail winds from the jet stream and hence routings with lower climate impacts have a large fuel penalty, whenever they leave the jet stream. Maximum reduction in climate impact increases the economic costs by 10–15%, due to higher fuel consumption, caused by a longer flight distance and lower flight levels. However, with only small changes to the air traffic routings and flight altitudes, climate reductions up to 25% can be achieved by only small changes in economic costs (less than 0.5%).

Sildenafil accelerates reentrainment of circadian rhythms after advancing light schedules

Mammalian circadian rhythms are generated by a master clock located in the suprachiasmatic nuclei and entrained by light-activated signaling pathways. In hamsters, the mechanism responsible for light-induced phase advances involves the activation of guanylyl cyclase, cGMP and its related kinase (PKG). It is not completely known whether interference with this pathway affects entrainment of the clock, including adaptation to changing light schedules. Here we report that cGMP-specific phosphodiesterase 5 is present in the hamster suprachiasmatic nuclei, and administration of the inhibitor sildenafil (3.5 mg/kg, i.p.) enhances circadian responses to light and decreases the amount of time necessary for reentrainment after phase advances of the light-dark cycle. These results suggest that sildenafil may be useful for treatment of circadian adaptation to environmental changes, including transmeridian eastbound flight schedules.

JET LAG IN ATHLETES AFTER EASTWARD AND WESTWARD TIME-ZONE TRANSITION

In healthy male top athletes several functions were measured after either a westbound flight over six time-zones (WEST: Frankfurt–Atlanta; n=13) or an eastbound flight over eight time-zones (EAST: Munich–Osaka; n=6). Under either condition the athletes performed two standardized exercise training units in the morning and in the afternoon within 24 h, investigations were done as controls in Germany and on day 1, 4, 6, and 11, after arrival. The primary aim of the study was to evaluate the effect of time-zone transitions on the 24h profiles of blood pressure (BP) and heart rate (HR) using an ambulatory BP device (SpaceLabs 90207), for up to 11 d after arrival at the destination. As additional parameters, we studied jet-lag symptoms, training performance, and training coordination by using visual analog scales. Finally, oral temperature and grip strength were measured, and saliva samples were analyzed for cortisol and melatonin. The study showed that all functions were disturbed on the first day after arrival at the destination, jet-lag symptoms remained until day 5–6 after WEST and day 7 after EAST, training performance was worst within the first 4 d after WEST. In accordance with earlier reports, cortisol, melatonin, body temperature, and grip strength were affected in their 24h profiles and additionally modified by the training units. Surprisingly, BP and HR were not only affected on the first day but also the time-zone transition led to an increase in BP after WEST and a decrease in BP after EAST. However, the training units seemed to influence the BP profile more than the time-zone transitions. HR rhythm was affected by both time-zone transitions and exercise. It is concluded that not only jet-lag symptoms but also alterations in physiological functions should be considered to occur in highly competitive athletes due to time-zone transition and, therefore, an appropriate time of reentrainment is recommended.

技術試験衛星V型(ETS-V)を用いた航空機データ通信実験

This paper describes the result of data communication experiment using a Boeing 747 cargo aircraft and Engineering Test Satellite V (ETS-V) conducted to develop and evaluate satellite data communication techniques for oceanic air traffic control. Circular patch antennas (peak gain: 7dBi) on board the B747 were used for transmission to and reception from the ETS-V. The B747 flew between Narita and Anchorage where the satellite elevation angle varied from 10°to 45°.Data transmission characteristics for three modulation schemes, BPSK, SS and PM, were measured and compared with theoretical ones. The result showed the followings. The degradation of data transmission characteristics were within the link margin for all modulation schemes. For BPSK (without FEC), transmission errors considerably increased in the eastbound flight due to signal level variation caused by the reflection on a wing. But, the increase of transmission errors was relatively small in the westbound flight for all modulation schemes.

Inter-relation of Temperature and Wind on the Route London—New York at 50 mb

The statistical relation between wind and temperature in the lower stratosphere is not only of theoretical interest but is of practical concern for the operation of supersonic aircraft since for example the incidence of abnormally high temperature together with strong head-winds could substantially increase the time of flight and reduce the pay-load. Temperature and tail-wind component have been correlated on the great-circle route between London and New York at 50 mb. The route was divided into six legs of approximately 500 nautical miles; at the mid-point of each leg, temperature and tail-wind component for an eastbound flight were obtained from daily charts for the period of the International Geophysical Year and its extension, July 1957 to June 1959 (U.S. Weather Bureau, 1960–63). Seasonal correlation coefficients were evaluated for each leg and for the route as a whole. The seasons in the lower stratosphere in middle latitudes differ from the conventional seasons except in summer (June–August). Although autumn has been taken as September–November, it appears that the transition to the winter type of circulation is usually completed by late October so that November should strictly be included in winter. However, the period December to March has been taken for winter; conditions in March are very variable from one year to another but on balance this month is probably more appropriate to winter than to spring.

EFFECT OF RAPID TRANSPOSITION AROUND THE EARTH ON DIURNAL VARIATION IN BODY TEMPERATURE.

SummaryThe diurnal pattern of body temperature was observed on 3 members of a family including a 6-year-old child for 2 weeks covering the period during and after an east-bound flight which resulted in an advance of daily routine as much as 10 hours. Adjustment of diurnal rhythm to a new local time was discussed with reference to the speed of transposition. With a rapid shift of local time zones the characteristics of the normal pattern were disturbed, but gradually approximated the new time pattern (approximately 40-50 minutes shift per day).