Haul Flights Research Articles

370: Ascent to Altitude in a Hypobaric Chamber Does Not Consistently Affect Serum D-Dimer Levels

Exposure to altitude may contribute to the hypercoaguable state observed during air travel. The objective of this study was to determine if ascent to altitude was associated with an increase in serum d-dimer (DD) levels over 8 hours, a time period chosen to simulate a “long haul flight.” We hypothesized that ascent to altitude would cause an increase in DDs.

Comparing the CO2 emissions and contrail formation from short and long haul air traffic routes from London Heathrow

Abstract This paper considers the relative climate impacts of long haul and short haul air travel. This is particularly important in the context of changing markets for air travel. New competing aircraft technologies will enhance competition between the hub and spoke model of aircraft operations and that of smaller aircraft operating direct routes for long haul trips. The substitution of shorter trips by high-speed rail could also free otherwise constrained airport capacity for additional long haul flights. Previous comparisons have focused on fuel consumption per passenger km so long haul trips, where a much higher proportion of the journey is in the relatively efficient cruise phase, are more efficient than shorter trips. This study considers the additional role of contrails, believed to be important for the net climate impact of aviation. Short aircraft trips tend not to reach the very high altitudes attained by long haul cruising aircraft and so encounter different atmospheric conditions and have different probabilities of contrail formation. By including consideration of the variability in contrail formation conditions throughout the year, estimates of the linear contrail produced along various aircraft trajectories are obtained. The potential to mitigate contrail impacts by altering the flight schedule is also discussed.

What's new in the other general journals

Randomised trials are rarely big enough, long enough, or powerful enough to give patients the information they want about rare but serious side effects. In an unusual move, researchers used...

Extended formulary nurse prescribing within contraceptive services

Jenny*, 23 years of age, attended a Young People's Open Access Clinic for a repeat prescription and supply of Microgynon 30, a combined oral contraceptive pill (COC). She had been using this method of contraception effectively since the age of 17 years and had not experienced any problems. On this occasion, Jenny was seeking advice regarding her recent pill taking. Additionally, Jenny informed me that she had just completed her training as an airhostess and would be working as a cabin-crew member on long haul flights to a variety of locations.

An analysis of European low-cost airlines and their networks

The growth of low-cost carriers (LCCs) is currently focused on the Western European market, where they represent the most determining factor in the evolution of airline networks. In this area, they stand for 18% of the total air transport supply according to seats. Limited to short and medium haul flights, networks are not too concentrated (no hubs). They are North–South, and compete with—when they have not replaced—some charter routes. The use of air freedoms beyond the fourth is still limited, but exclusive routes are a frequent phenomenon linked to the option for secondary (urban or regional) airports and/or niches. Finally, low-cost carriers give fresh impetus to point-to-point routes by drawing new networks complementing those of full service network carriers (FSNCs). If no hubs as such can be found in these new networks, significant concentrations characterize the major bases. The geography of low-cost networks is to a large extent the geography of EU air transport liberalization.

Effect of high altitude commercial air travel on oxygen saturation

Air travel has increased steadily over the last decade, and its effect on the health of passengers has been the subject of much debate. There is a paucity of evidence on the effects of air travel on oxygen saturation in general populations. The peripheral oxygen saturation and pulse rate of 84 passengers, aged 1-78 years, were measured by pulse oximetry at round level and altitude during air travel. There was a statistically significant reduction in oxygen saturation in all passengers travelling long haul and short haul flights (p < 0.05). The mean [range] (SD) SpO(2) for all flights at ground level was 97% [93-100] (1.33) and at cruising altitude 93% [85-98] (2.33). Fifty-four per cent of passengers had SpO(2) values of 94% or less at cruising altitude. This is a value which may prompt physicians to administer supplemental oxygen in hospital patients.

Identifying flight fatigue factors: An econometric modeling approach

The paper looks at responses of crewmembers of six Taiwan air carriers who were asked to report their levels of fatigue before takeoff and after landing. Ordinal probit models are employed to estimate three fatigue models for different flight operations and serve as vehicles to investigate flight fatigue factors and identify their relative significance. The top three factors for long haul flights are found to be sleep quality at home, sleep quality on aircraft and “nod-off “experiences; for regional flights, age, extra non-flying tasks on the ground, and experiences of fatigue during flight operations are important; and for domestic flights poor cockpit environment, age, and experiences of fatigue during flight operations are relevant.

The effect of high altitude commercial air travel on oxygen saturation

Air travel has increased steadily over the last decade, and its effect on the health of passengers has been the subject of much debate. There is a paucity of evidence on the effects of air travel on oxygen saturation in general populations. The peripheral oxygen saturation and pulse rate of 84 passengers, aged 1-78 years, were measured by pulse oximetry at round level and altitude during air travel. There was a statistically significant reduction in oxygen saturation in all passengers travelling long haul and short haul flights (p < 0.05). The mean [range] (SD) SpO(2) for all flights at ground level was 97% [93-100] (1.33) and at cruising altitude 93% [85-98] (2.33). Fifty-four per cent of passengers had SpO(2) values of 94% or less at cruising altitude. This is a value which may prompt physicians to administer supplemental oxygen in hospital patients.

Risk of venous thromboembolism greatest within two weeks of long-haul flight*1

After a long haul flight, when are people at greatest risk of developing deep vein thrombosis? Retrospective review and record linkage study. Of the 13,184 people admitted to a Western Australia hospital during 1981–1999 with a primary diagnosis of venous thromboembolism, 5408 (41%) had arrived on an international flight sometime during the same 18 year period. Of these, 153 Australian citizens and 438 non-Australian citizens were admitted within 100 days of flight arrival (see Table 1). Venous thromboembolism was significantly more likely within the first 14 days of flight arrival for both Australian and non-Australian citizens, compared with the number of events expected under the assumption of a uniform distribution across 100 days (P<0.001 for both comparisons). However, these results may have limited generalisability (see notes).Table 1 Observed and expected venous thromboembolism events by time (days) since flight arrival.CitizenshipDays since most recent flight arrival0–1415–3031–6061–100TotalAustralianObserved46233252153Expected*102.6113.2212.3283.0711.1Non-AustralianObserved200697891438Expected†105.3116.2217.9290.5729.9*Estimated from the total number of arrivals of Australian citizens in Western Australia (4.8 million) and the age- and sex-specific baseline rates for venous thromboembolism in the Western Australian population. There were consistently fewer observed venous thromboembolism events than expected events, suggesting a ‘healthy traveller effect’.†Also estimated from the baseline rates for venous thromboembolism in the Western Australian population. There appears to be an increased risk of venous thromboembolism for 2 weeks after arrival from a long-haul flight.

Risk of venous thromboembolism greatest within two weeks of long-haul flight

Question After a long haul flight, when are people at greatest risk of developing deep vein thrombosis? Study design Retrospective review and record linkage study. Main results Of the 13,184 people admitted to a Western Australia hospital during 1981–1999 with a primary diagnosis of venous thromboembolism, 5408 (41%) had arrived on an international flight sometime during the same 18 year period. Of these, 153 Australian citizens and 438 non-Australian citizens were admitted within 100 days of flight arrival (see Table 1). Venous thromboembolism was significantly more likely within the first 14 days of flight arrival for both Australian and non-Australian citizens, compared with the number of events expected under the assumption of a uniform distribution across 100 days ( P<0.001 for both comparisons). However, these results may have limited generalisability (see notes). Table 1 Observed and expected venous thromboembolism events by time (days) since flight arrival. Citizenship Days since most recent flight arrival 0–14 15–30 31–60 61–100 Total Australian Observed 46 23 32 52 153 Expected * 102.6 113.2 212.3 283.0 711.1 Non-Australian Observed 200 69 78 91 438 Expected † 105.3 116.2 217.9 290.5 729.9 *Estimated from the total number of arrivals of Australian citizens in Western Australia (4.8 million) and the age- and sex-specific baseline rates for venous thromboembolism in the Western Australian population. There were consistently fewer observed venous thromboembolism events than expected events, suggesting a ‘healthy traveller effect’. †Also estimated from the baseline rates for venous thromboembolism in the Western Australian population. Authors’ conclusions There appears to be an increased risk of venous thromboembolism for 2 weeks after arrival from a long-haul flight.

Coffee, Tea, or …?: A Markov Decision Process Model for Airline Meal Provisioning

This paper develops and analyzes a finite horizon Markov decision process model for the airline meal provisioning activity focusing explicitly on developing policies for determining and revising the number of meals to upload. Using one year of daily data from over 40 flights, the paper shows that the optimal policies can result in both improved customer service and significant dollar savings, especially in long haul flights. It also applies the model to derive an efficient frontier and investigate tradeoffs between having too few and too many meals on a flight.

Deep vein thrombosis and air travel: record linkage study

Objective To investigate the time relations between long haul air travel and venous thromboembolism.Design Record linkage study using the case crossover approach.Setting Western Australia.Participants 5408 patients admitted to hospital with...

Air transport cruise altitude restrictions to minimize contrail formation

While quantification of the effects of NO x and water vapor is still at an early stage there is evidence that contrail formation could make a significant contribution to global warming. This paper builds on previous research that analyzed a policy of restricting air transport cruise altitudes to eliminate contrail formation. Our previous work [Transport. Res. D 7(6) (2002) 451], examined altitude restrictions in European airspace and concluded that this could be a beneficial policy for reducing climate change impacts from aviation. Since most of the flights in European airspace are short-haul flights, this paper evaluates the trade-offs between altitude restrictions, fuel burn and journey times for longer haul flights of up to 6000 nm. Our focus is on the North Atlantic and US airspace and we examine potential contrail fraction to determine optimal cruise altitudes for reducing contrail formation. Changes in fuel burn and travel times associated with flight levels of 18,000 and 31,000 ft for different aircraft types are analyzed. We find that, in most cases, CO 2 emission increases would be unlikely to entirely counteract the benefit of possible reductions in contrail formation. For some aircraft types, the percentage increase in emitted CO 2 was found to be strongly dependent on journey length. In general, journey times appear not to be a major issue except for some aircraft types. Our results suggest that reducing aircraft cruise altitudes could be a beneficial policy for mitigating climate change impacts from the aviation sector. This is clearly dependent on aircraft type and the distances traveled, but more importantly on ambient atmospheric conditions which can vary significantly between regions and due to daily variation. This suggests that real time flight planning to minimize contrail formation should be investigated as a possible climate mitigation policy.

Air transport cruise altitude restrictions to minimize contrail formation

While quantification of the effects of NO x and water vapor is still at an early stage there is evidence that contrail formation could make a significant contribution to global warming. This paper builds on previous research that analyzed a policy of restricting air transport cruise altitudes to eliminate contrail formation. Our previous work [Transport. Res. D 7(6) (2002) 451], examined altitude restrictions in European airspace and concluded that this could be a beneficial policy for reducing climate change impacts from aviation. Since most of the flights in European airspace are short-haul flights, this paper evaluates the trade-offs between altitude restrictions, fuel burn and journey times for longer haul flights of up to 6000 nm. Our focus is on the North Atlantic and US airspace and we examine potential contrail fraction to determine optimal cruise altitudes for reducing contrail formation. Changes in fuel burn and travel times associated with flight levels of 18,000 and 31,000 ft for different aircraft types are analyzed. We find that, in most cases, CO2 emission increases would be unlikely to entirely counteract the benefit of possible reductions in contrail formation. For some aircraft types, the percentage increase in emitted CO2 was found to be strongly dependent on journey length. In general, journey times appear not to be a major issue except for some aircraft types. Our results suggest that reducing aircraft cruise altitudes could be a beneficial policy for mitigating climate change impacts from the aviation sector. This is clearly dependent on aircraft type and the distances traveled, but more importantly on ambient atmospheric conditions which can vary significantly between regions and due to daily variation. This suggests that real time flight planning to minimize contrail formation should be investigated as a possible climate mitigation policy.

The effects of air transport on the behaviour and heart rate of horses

Although many horses ( Equus caballus) travel by air, there is little information on the effect of this type of transport on their physiology and behaviour. This study monitored the behaviour and heart rate of horses during air transport to identify events that might be stressful, and to compare these measures across long and short haul air journeys. Body temperatures prior to and after transport were also measured. Heart rate was recorded before road transport to the airport to obtain resting levels, and recordings continued throughout subsequent road and air journeys. A range of social activities, together with body postures associated with balancing and resting, were recorded over a series of 30 min observation periods during the air journey. The air temperature and relative humidity (RH) in the aircraft were also recorded. During short haul flights (3–4 h), 16 horses were sampled. Heart rates were significantly higher ( P<0.05) during transitional events (i.e. while loading and unloading the truck and aircraft, and during ascent and descent) than when horses were resting or when the aircraft was in flight. In level flight, horses’ heart rates were close to resting levels and they would regularly doze and rest. In comparison, during ascent and descent, social behaviour, including aggression and submission, increased, and horses were seen to regularly change body postures to maintain balance. During long haul flights (10–15 h), 19 horses were sampled. The difference in journey length did not change how horses responded to transport events. Air temperature and humidity were highest when the plane was stationary (e.g. during loading, unloading, refuelling and delays). Although some sharp increases in heart rate and activities suggested agitation during transitional stages of air transport, these events did not appear to be frequent or long enough to be a significant welfare concern. Horses appear to adapt well to air travel under the conditions studied.

Travel-induced thrombosis: an update

Travel-related disorders are a well known problem. In the last years many cases of deep venous thrombosis (DVT) and pulmonary thromboembolism (VTE) were published after several hours lasting journeys by airplane, but also by car, bus and railway. This condition was termed "travel-thrombosis" or "economy class syndrome" for long haul flights. At present the precise incidence for travel-thrombosis is not known. Accepted contributing factors for the development of travel-thrombosis are sitting in a cramped position for several hours, low humidity due to climatisation with the risk for dehydration and increased blood viscosity, reduced fluid intake as well as travellers related risk factors. Whether the special situation in the cabin of an airplane, e.g. mild hypoxia, is an essential contributing factor for DVT and VTE, is controversially discussed. This review will present very recent guidelines of an expert meeting concerning the risk groups for travel-thrombosis (low, moderate and high risk). In addition recommendations for prophylaxis of travel-thrombosis adapted to the different risk groups (leg exercise, adequate fluid intake, compression stockings, low molecular weight heparins) are given.

Deep vein thrombosis following calf strain: a case study

Deep vein thrombosis (DVT) has been the subject of considerable media attention after a number of deaths and scares in apparently low risk individuals following long haul flights. While many contributory factors have been put forward for the development of DVT, few cases have been reported following muscle strain. The recent publicity surrounding the calf strain sustained by Steve Waugh, the Australian cricket captain, during the Ashes series was initially unremarkable. The case was however, subsequently complicated by the development of DVT following his return (long haul) flight to Australia. Latest reports indicate that following anticoagulant treatment he has made a full recovery and returned to playing. This case could easily be dismissed as a ‘one off’ or an unusual set of circumstances. The following case report illustrates that DVT following calf strain is by no means unique. The ramifications of these cases may have serious implications for Physicians and manual therapists working in sports medicine.

Air travel--a disease risk?

Civil air traffic moves in an altitude that is dangerous for human beings without technical aids. Low temperature and humidity, reduced air pressure combined with oxygen pressure, seasonal depending high concentration of ozone and cosmic radiation may also be risk factors. Further risks on long haul flights may be jet lag, risk of economy class syndrome and contact with permethrin, because of disinsection before take-off out of tropical regions. The aim of an airline is to offer good cabin air quality, comfort and security for all passengers, may they be healthy, old, disabled or sick. Medical incidences on board arise and passengers expect modern equipment such as doctor's kit and defibrillators.

Deep Vein Thrombosis in Airline Passengers — The Incidence of Deep Vein Thrombosis and the Efficacy of Elastic Compression Stockings

A prospective study to determine the incidence of deep vein thrombosis in passengers on long haul flights, and to determine the efficacy of elastic compression stockings in reducing this incidence. Two hundred patients over the age of 50, with no past history of venous throm-boembolic disease. no co-existing medical problems. and no specific risk factors, undergoing flights of eight hours or more, have been accessed. All patients have undergone Duplex ultra-sound imaging two weeks prior to departure. Immediately prior to departure. a repeat Duplex ultrasound scan was carried out, and blood taken for D-dimer and thrombin antithrombin complex (TAT) as markers of a hypercoagulable state and soluble vascular cell adhesions mol-ecule (VCAM-1). All patients completed a pre-travel questionnaire. The patients were randomly allocated to receive or not receive elastic compression stockings. On return, each patient was again scanned, and a further blood sample taken for analysis. Those patients with high levels of D-dimer, TAT or VCAM-1, underwent a full thrombophilia screen. Those patients with a positive Duplex scan on visit one or two were excluded from the study. Those patients with a positive scan on return were considered to have developed thromboembolic disease, and underwent further investigations. The results are being analysed on an intention to treat basis. The stUdy will conclude when 100 patients have been recruited to each group.

Deep vein thrombosis in airline passengers — the incidence of deep vein thrombosis and the efficacy of elastic compression stockings

A prospective study to determine the incidence of deep vein thrombosis in passengers on long haul flights, and to determine the efficacy of elastic compression stockings in reducing this incidence....