Calculating and communicating ensemble-based volcanic ash dosage and concentration risk for aviation

During volcanic eruptions, aviation stakeholders require an assessment of the volcanic ash hazard. Operators and regulators are required to make fast decisions based on deterministic forecasts, which are subject to various sources of uncertainty. For a robust decision to be made, a measure of the uncertainty of the hazard should be considered but this can lead to added complexity preventing fast decision making. Here a proof-of-concept risk matrix approach is presented that combines uncertainty estimation and volcanic ash hazard forecasting into a simple warning system for aviation. To demonstrate the methodology, an ensemble of 600 dispersion model simulations is used to characterise uncertainty (due to eruption source parameters, meteorology and internal model parameters) in ash dosages and concentrations for a hypothetical Icelandic eruption. To simulate aircraft encounters with volcanic ash, trans-Atlantic air routes between New York (JFK) and London (LHR) are generated using time-optimal routing software. This approach has been developed in collaboration with operators, regulators and engine manufacturers; it demonstrates how an assessment of ash dosage and concentration risk can be used to make fast and robust flight-planning decisions even 23 when the model uncertainty spans several orders of magnitude. The results highlight the benefit of using an ensemble over a deterministic forecast and a new method for visualising dosage risk along flight paths. The risk matrix approach is applicable to other aviation hazards such as SO2 dosages, desert dust, aircraft icing and clear-air turbulence and is expected to aid flight-planning decisions by improving the communication of ensemble-based forecasts to aviation

Civil aviation, air pollution and human health

Air pollutant emissions from aircraft have been subjected to less rigorous control than road traffic emissions, and the rapid growth of global aviation is a matter of concern in relation to human exposures to pollutants, and consequent effects upon health. Yim et al (2015 Environ. Res. Lett. 3 034001) estimate exposures globally arising from aircraft engine emissions of primary particulate matter, and from secondary sulphates and ozone, and use concentration-response functions to calculate the impact upon mortality, which is monetised using the value of statistical life. This study makes a valuable contribution to estimating the magnitude of public health impact at various scales, ranging from local, near airport, regional and global. The results highlight the need to implement future mitigation actions to limit impacts of aviation upon air quality and public health. The approach adopted in Yim et al only accounts for the air pollutants emitted by aircraft engine exhausts. Whilst aircraft emissions are often considered as dominant near runways, there are a number of other sources and processes related to aviation that still need to be accounted for. This includes impacts of nitrate aerosol formed from NOx emissions, but probably more important, are the other airport-related emissions from ground service equipment and road traffic. By inclusion of these, and consideration of non-fatal impacts, future research will generate comprehensive estimates of impact related to aviation and airports

Towards dissociation of passengers and baggage

Dissociation of passenger travel and baggage delivery is being considered as one of the radical innovations in future air transport. This paper elaborates on this idea to identify potential benefits as well as implementation challenges. It is argued that complete end-to-end dissociation involving also the air segment is critically dependent on dissociation provided first in the ground segment. The end-to-end dissociation is likely to lead to full outsourcing of baggage services outside airports to the 3rd party providers while treating baggage as cargo at airports. Even though large scale dissociation may be challenging or less beneficial, the situation appears very different at smaller scales. In order to obtain initial assessment of baggage volumes expected in the ground segment in a large metropolitan area, arrival and departure flight data from 4 major London airports were used to infer the baggage flows between these airports and the Greater London area. Our analysis estimates that the required baggage transport and processing capacity is as large as 100’s of bags per hour per a baggage distribution center in the city. This capacity can be reduced by at least 30% provided that the baggage flow variations are suppressed by exploiting temporary storage facilities

Towards operational use of aircraft‐derived observations: a case study at London Heathrow airport

Mode-Selective Enhanced Surveillance (Mode-S EHS) aircraft reports can be collected at a low-cost, and are readily available around busy airports. The new work presented here demonstrates that observations derived from Mode-S EHS reports can be used to study the evolution of temperature inversions since the data have a high spatial and temporal frequency. This is illustrated by a case study centred around London Heathrow airport for the period 4 to 5 January 2015. Using Mode-S EHS reports from multiple aircraft and after applying quality control criteria, vertical temperature profiles are constructed by aggregating these reports at discrete intervals between the surface and 3000m. To improve these derived temperatures, four smoothing methods using low-pass filters are evaluated. The effect of smoothing reduces the variance in the aircraft derived temperature by approximately half. After smoothing, the temperature variance between the altitudes 3000m and 1000m is 1K to 2K; and below 1000m it is 2K to 4K. While the differences between the four smoothing methods are small, exponential smoothing is favoured because it uses all available Mode-S EHS reports. The resulting vertical profiles may be useful in operational meteorology for identifying elevated temperature inversions above 1000m. However, below 1000m they are less useful because of the reduced precision of the reported Mach number. A better source of in situ temperature observations would be for aircraft to use the meteorological reporting function of their automatic dependent surveillance (ADS) system

The Rebound Effect in the Aviation Sector

The rebound effect, i.e., the (partial) offset of the energy efficiency improvement potential due to a reduction in marginal usage costs and the associated increase in consumer demand, has been extensively studied for residential energy demand and automobile travel. This study presents a quantitative estimate of the rebound effect for an air traffic network including the 22 busiest airports, which serve 14 of the highest O-D cities within the domestic U.S. aviation sector. To satisfy this objective, passenger flows, aircraft operations, flight delays and the resulting energy use are simulated. Our model results indicate that the average rebound effect in this network is about 19%, for the range of aircraft fuel burn reductions considered. This is the net impact of an increase in air transportation supply to satisfy the rising passenger demand, airline operational effects that further increase supply, and the mitigating effects of an increase in flight delays. Although the magnitude of the rebound effect is small, it can be significant for a sector that has comparatively few options for reducing greenhouse gas emissions

A framework for the classification and prioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas

© 2015 American Institute of Aeronautics and Astronautics Inc, AIAA. All right reserved.Typically major cities (London, New York, Tokyo) are served by several airports effectively creating a Multi-Airport System or Metroplex. The operations of the Metroplex airports are highly dependent on one another, which renders their efficient management difficult. This paper proposes a framework for the prioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas. The framework consists of three components. The first component presents a new procedure for clustering arrival and departure flights into dynamic routes based on their temporal and spatial distributions through the identification of the important traffic flow patterns throughout the day of operations. The second component is a novel Analytic Hierarchy Process model for the prioritization of the dynamic routes, accounting for a set of quantitative and qualitative characteristics important for Multi-Airport Systems operations. The third component is a priority-based model for the facility location of the optimal terminal waypoints (fixes), which accounts for the derived priorities of each dynamic route, while meeting the required separation distances. The proposed Analytic Hierarchy Process model characteristics are validated by subject matter experts. The developed framework is applied to the London Metroplex case study

Comparison of aircraft-derived observations with in situ research aircraft measurements

Mode Selective Enhanced Surveillance (Mode-S EHS) reports are aircraft-based observations that have value in numerical weather prediction (NWP). These reports contain the aircraft's state vector in terms of its speed, direction, altitude and Mach number. Using the state vector, meteorological observations of temperature and horizontal wind can be derived. However, Mode-S EHS processing reduces the precision of the state vector from 16-bit to 10-bit binary representation. We use full precision data from research grade instruments, on-board the United Kingdom's Facility for Atmospheric Airborne Measurements, to emulate Mode-S EHS reports and to compare with derived observations. We aim to understand the observation errors due to the reduced precision of Mode-S EHS reports. We derive error models to estimate these observation errors. The temperature error increases from 1.25 K to 2.5 K between an altitude of 10 km and the surface due to its dependency on Mach number and also Mode-S EHS precision. For the cases studied, the zonal wind error is around 0.50 ms− 1 and the meridional wind error is 0.25 ms− 1. The wind is also subject to systematic errors that are directionally dependent. We conclude that Mode-S EHS derived horizontal winds are suitable for data assimilation in high-resolution NWP. Temperature reports may be usable when aggregated from multiple aircraft. While these reduced precision, high frequency data provide useful, albeit noisy, observations; direct reports of the higher precision data would be preferable

Preliminary noise assessment of aircraft with distributed electric propulsion

Electric and hybrid-electric propulsion technologies in aviation are becoming more attractive for aviation stakeholders not only due to the resulting reduction or elimination of the dependency on oil, whose availability and price are uncertain, but also because they are more reliable and efficient than traditional internal combustion engines. Moreover, combined with distributed electric propulsion (DEP), these technologies have shown potential in significantly reducing civil aircraft community noise impact and contribute towards delivering the strict mid-to-long-term environmental goals set by organisations worldwide, such as ACARE and NASA. This paper examines the noise impact of a concept tube and wing aircraft that falls in the A320 category and features various DEP systems using different power supply units (turboshaft engines or batteries) and number of electric propulsors. Meanwhile, considerations required for the transition from conventional to electric propulsion are discussed. Estimated Noise-Power-Distance (NPD) curves and noise exposure contour maps are also presented. It is concluded that indeed, the propulsors’ number is a key parameter for optimising the environmental performance of DEP aircraft and hence maximising the noise benefits. Also, it is shown that based on the entry into service year (2035) technology, totally electric aircraft tend to have a larger noise footprint than aircraft using hybrid electric propulsion systems

A framework for managing airport grasslands and birds amidst conflicting priorities

Management of modern airports is a task beset by conflicting priorities. Airports are vital to the global market economy, but impose costly environmental disturbances including habitat loss, noise, reduced air quality, erosion, introduction of invasive organisms, and polluted storm-water runoff (Blackwell et al. 2009). Airport environments also attract some wildlife hazardous to aviation safety, namely species involved in wildlife-aircraft collisions or ‘strikes’ (ICAO 2001, Blackwell et al. 2009, DeVault et al. 2011). Since 1912 at least 276 human lives have been lost due to bird strikes (Thorpe 2010), and from 1990 to 2010, more than 106 000 bird strikes involving civil aircraft were reported to the US Federal Aviation Administration (FAA; http://wildlife-mitigation. tc.faa.gov/wildlife/). Dolbeer (2006) reported that for strikes resulting in substantial aircraft damage (ICAO 1989), 66% occurred below 152 m altitude and within 1.5 km of a runway for airports servicing piston-powered aircraft only, and within 3 km of a runway for airports servicing turbine-powered aircraft (FAA 2009). Consequently, aviation authorities prioritize human safety over wildlife conservation in management of airport habitats (ICAO 2001, FAA 2009). Despite these problems, airports have been proposed as candidates for biodiversity conservation (Kelly & Allan 2006, Blackwell et al. 2009). For example, Kutschbach- Brohl et al. (2010) report that airport grasslands can provide habitat for a range of arthropod communities (e.g. Lepidoptera), and suggest the possibility of conserving these communities while minimizing provision of prey resources to birds recognized as hazardous to aviation. Moreover, declines in grassland bird populations in Europe and North America due to agricultural intensification and development have focused attention on enhancing quality and quantity of remnant grasslands (Herkert 1994, Vickery et al. 2004), including airport grasslands. In North America, airport properties have been identified as key areas of remnant grasslands important to obligate grassland bird species; species that both nest and forage in grasslands (Vickery et al. 1994, Askins et al. 2007). Airport properties in the contiguous USA include \u3e 330 000 ha of grassland, mostly annually mown areas, constituting 39–50% of airport property (DeVault et al. 2012). However, there is little research specific to airport environments that considers food resources for birds (Bernhardt et al. 2010, Kutschbach-Brohl et al. 2010), how birds perceive and react to predation risk (Baker & Brooks 1981) or disturbance (Kershner & Bollinger 1996), and no adequate assessment of how grassland management might affect strike risk (Blackwell et al. 2009, Martin et al. 2011). In this context, we contend that promoting conservation of obligate grassland birds and managing to reduce bird hazards to aviation safety combines two potentially conflicting objectives in a single management framework. Ecologically based guidance to solve this potential conflict is limited, if not oversimplified. Here, we question the potential use of airports to conserve grassland birds, and assess the challenges in managing airport grasslands in light of current ecological and behavioral frameworks. We consider conditions for conservation of obligate grassland birds on airports, and evidence on the use of airports by frequently struck, grassland birds (both obligate and facultative). We also provide a framework to manage grassland birds at airports, given current information and uncertainty. Because of the availability of strike data via the FAA, our focus is on North America. However, problems associated with bird use of airport grasslands are international (ICAO 2001). Therefore, our ultimate purpose is better to inform current management, but also identify research gaps and establish specific predictions that will guide future studies on the ecological basis of use of airport grasslands by birds