Effect of radii of exemption on ground delay programs with operating cost based cruise speed reduction

When a ground delay program (GDP) is defined, a radius of exemption is typically set to exclude from having to realize ground delay aircraft departing from greater distances than the selected radius distance. A trade-off exists when defining this radius: big radii distribute the required delay among more aircraft and reduce the airborne holding delay close to the destination airport, while the probability to realize unnecessary delay increases if the program is canceled before planned. In order to overcome part of this drawback, a cost based cruise speed reduction strategy aiming at realizing airborne delay was suggested by the authors in previous publications. By flying slower, at a specific speed, aircraft that are airborne can recover part of their initially assigned delay without incurring extra cost if the GDP is canceled before planned. In this paper, the effect of the exemption radius is assessed when applying this strategy and a case study is presented by analyzing all the GDPs that took place at Chicago O'Hare International Airport during one year. Results show that by the introduction of this technique, more delay can be saved. Thus, it is possible to define larger radii of exemption, reducing partially the drawbacks associated with smaller radii.Peer ReviewedPostprint (published version

An optimisation framework for aircraft operators dealing with capacity-demand imbalances in SESAR

This paper presents a framework for the negotiation phase that is foreseen in the new operational concept proposed in the Single European Sky Research (SESAR) program. In particular, this paper describes a possible strategy for the airspace users in order to deal with the Collaborative Decision Making (CDM) process that is expected in this future scenario. In the SESAR scenario, airspace users will become owners of their trajectories and they will be responsible to solve possible mismatches between capacity and demand in a particular airspace sector. The aim of this strategy is to improve the efficiency in the CDM process by computing the different operational costs associated to different solutions that may solve a particular demand-capacity imbalance in the airspace. This will allow them to optimise their operating costs while reducing fuel consumption and therefore being more environmentally friendly. Some suggestions have already been done for the CDM mechanism, for instance the use of auctions. However, the different options that aircraft operators might use have not yet been sufficiently investigated. In this paper, the authors propose an optimisation framework for aircraft operators aimed at computing 4D trajectories with time constraints to deal, in this way, with possible airspace regulations. Once a nominal flight plan and a potential regulation is known, it is suggested to compute several possible alternative flight plans (including rerouting, but also altitude and speed profiles) that may solve the capacity-demand problem. If more than one regulation is applied to the flight, a tree of options is subsequently computed. The cost of each optimised the option is also calculated in order to allow the airspace users to initiate the negotiation process with other airlines. Finally, a preliminary example is given at the end of this paper in order to better illustrate the proposed methodology.Postprint (published version

Fuel consumption assessment for speed variation concepts during the cruise phase

Postprint (published version

An Assessment for UAS Traffic Awareness Operations

Technology evolution in the field of Unmanned Aircraft Systems (UAS) will affect the Air Traffic Management (ATM) performance regarding to new military and civil applications. UAS, as new airspace users, will represent new challenges and opportunities to design the ATM system of the future. The goal of this future ATM network is to keep intact (or improve) the network in terms of security, safety, capacity and efficiency level. On the other hand, most UAS are, at present, designed for military purposes and very few civil applications have been developed mainly because the lack of a regulation basis concerning their certification, airworthiness and operations. Therefore, UAS operations have always been solutions highly dependent on the mission to be accomplished and on the scenario of flight. The generalized development of UAS applications is still limited by the absence of systems that support the development of the actual operations. Moreover, the systematic development of UAS missions leads to many other operational risks that need to be addressed. All this elements may delay, increase the risk and cost in the implementation of a new UAS application.Peer ReviewedPostprint (published version

Fibrosis glútea: ¿esencial o secundaria?

Constatamos la rara frecuencia de esta afección presentando 5 observaciones de Fibrosis Glútea recogidas en tres casos clínicos estudiados. Dos son bilaterales y uno afecta a un solo glúteo. Habiéndose invocado, por los autores consultados, etiologías diversas, actualmente sigue siendo desconocida. Creemos de interés resaltar que los casos presentados se trataron en las etapas finales de crecimiento, mientras que los referidos en la literatura consultada todos han recibido tratamiento quirúrgico en edad temprana. El tratamiento es de resultado satisfactorio, independientemente de la edad y de la técnica quirúrgica empleada.Three patients affected with gluteal fibrosis are colected by the authors. Two cases had bilateral presentation and one patient was unilateral. According to the literature, the aetiology continue to be unknow. All patients were treated at the end of growthing period, while all cases collected in the literature were treated early. The results have been satisfactory without relation to age or the surgical procedure employed

An assessment for UAS depart and approach operations

Unmanned Aerial Systems (UAS) have great potential to be used in a wide variety of civil applications such as environmental applications, emergency situations, surveillance tasks and more. The development of Flight Control Systems (FCS) coupled with the availability of other Commercial Off-The Shelf (COTS) components is enabling the introduction of UAS into the civil market. The sophistication of existing FCS is also making these systems accessible to end users with little aeronautics expertise. However, much work remains to be done to deliver systems that can be properly integrated in standard aeronautical procedures used by manned aviation. In previous research advances have been proposed in the flight plan capabilities by offering semantically much richer constructs than those present in most current UAS autopilots. The introduced flight plan is organized as a set of stages, each one corresponding to a different flight phase. Each stage contains a structured collection of legs inspired by current practices in Area Navigation (RNAV). However, the most critical parts of any flight, the depart and approach operations in an integrated airspace remain mostly unexplored. This paper introduces an assessment of both operations for UAS operating in VFR and IFR modes. Problems and potential solutions are proposed, as well as an automating strategy that should greatly reduce pilot workload. Although the Document type: Conference objec

Agent-based simulation framework for airport collaborative decision making

Airport C ollaborative Decision Making (A - CDM) is based on information sharing. A better use of resources can be attained w hen the different stakeholders at airport operations share their more accurate and updated information . One of the main difficulties when dealing with this information sharing concept is the number of stakeholders involved and their different interest and behaviour : aircraft operators , gro und handling companies, airport authority, air traffic control and the Central Flow Management Unit . It is paramount to quantify the benefit of an airport collaborative decision making strategy in order to involve all these different organisations. Simulat ions are required to analyse the overall system and its emerging behaviour . This paper presents the development and initial t est ing of a n agent - based framework , which allows this behavioural analysis to be done . The simulator explicitly represents the diff erent stakeholders involved in the A - CDM and the interactions between them during the 16 milestones defined by EUROCONTROL o n its A - CDM implementation manual . T his framework allows independent gradual development of local behaviours and optimisation, and a gradual increase on complexity and fidelity on the simulationsPeer ReviewedPostprint (published version

In-flight cost index optimisation upon weather forecast updates

This paper presents an optimisation framework to compute the altitude and speed profiles of a trajectory in the execution phase of the flight, such that the expected total cost (ETC) of the operation is minimised (i.e. modelling the expected cost of delay and fuel – including arrival uncertainties – at the arrival gate). This is achieved with a two-stage optimisation strategy: a trajectory optimiser that minimises a generalised direct operating cost function, for a given cost index; and an upper-level optimiser, which obtains the best cost index that minimises the ETC. Several case studies are presented for different departure delays, while considering the impact of two different weather forecast updates too: a region with relative high head-winds appearing half way across teh flight; and a cold atmosphere scenario, with a tropopause altitude lower than standard conditions. ETC savings with respect to following the operational flight plan increase with departure delay, as expected. Due to the non-linearity of the cost function, however, the benefits of considering the weather update depend on the actual value of the departure delay, showing the convenience of integrating the proposed approach into a crew decision support tool in order to avoid sub-optimal decisions.This work has been performed as part of Pilot3 innovation action which has received funding from the Clean Sky 2Joint Undertaking (JU) under grant agreements No 863802. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Clean Sky 2 JU members other than the Union.Peer ReviewedPostprint (author's final draft

Enhanced Demand and Capacity Balancing based on alternative trajectory options and traffic volume hotspot detection

Nowadays, regulations in Europe are applied at traffic volume (TV) level consisting in a reference location, i.e. a sector or an airport, and in some traffic flows, which act as directional traffic filters. This paper presents an enhanced demand and capacity balance (EDCB) formulation based on constrained capacities at traffic volume level. In addition, this approach considers alternative trajectories in order to capture the user driven preferences under the trajectory based operations scope. In fact, these alternative trajectories are assumed to be generated by the airspace users for those flights that cross regulated traffic volumes, where the demand is above the capacity. For every regulated trajectory the network manager requests two additional alternative trajectories to the airspace users, one for avoiding the regulated traffic volumes laterally and another for avoiding it vertically. This paper considers that the network manager allows more flexibility for the new alternative trajectories by removing restrictions in the Route Availability Document (RAD). All the regulated trajectories (and their alternatives) are considered together by the EDCB model in order to perform a centralised optimisation minimising the the cost deviation with respect to the initial traffic situation, considering fuel consumption, route charges and cost of delay. The EDCB model, based on Mixed-Integer Linear Programming (MILP), manages to balance the network applying ground delay, using alternative trajectories or both. A full day scenario over the ECAC area is simulated. The regulated traffic volumes are identified using historical data (based on 28th July of 2016) and the results show that the EDCB could reduce the minutes of delay by 70%. The cost of the regulations is reduced by 11.7%, due to the reduction of the delay, but also because of the savings in terms of fuel and route charges derived from alternative trajectories.Peer ReviewedPostprint (published version