Continuous Descent Approach Research Articles

Obsolescence in Aviation Systems of Systems with Applications in ATM

Systems-of-Systems theory is enlarging the perspective that engineers have on the objects of their work. Previously, efforts were focused at the system level, and by managing system inputs and outputs, all interactions between systems were thought to be addressed. With age, a system-of-systems designed individually at different moments in time will degrade as an overall fitness to purpose, will grow to a certain degree of obsolescence. In aviation this is most evident since systems invented and put in place 60 years ago are still operating. The assumptions made originally when the system was created became obsolete, gradually or in quantum leaps. This paper uses examples from air navigation to illustrate that the fitness for purpose for an individual system does change over time and with the changes in the environment the system is working in. The first time a system is established as an industry standard, its first design, and its first architecture presumably best fit the requirements, the specifications. Although these specifications of the system do not change in time, the fitness to the purpose does change and usually decays. This is only obvious in a systems-of-systems analysis, done for the system now part of a system-of-systems. The paper studies the following cases of obsolescence with impact on Air Traffic Management: Radar Altimeters, ILS Glide Slope intercept from above, Continuous Descent Approach effects on turbine engines, and evolution of SSR transponder utility.

Modelling of aircraft trajectories for emergency landing using kinematoid chains

Most methods that compute trajectories for un- or low-powered flight operate under simplifying assumptions such as constant curve radii and wind conditions. Likewise, changes of air density with altitude that lead to significant differences between equivalent airspeed (EAS) und true airspeed (TAS) are often not considered. Some approaches are based on Dubins paths, which are introduced in Dubins LE (Am J Math 79: 497, 1957). They combine three sections to form a trajectory, which is the shortest from a given start to an end position (In the original work, the position extended by the heading, is referred to as configuration. Since configuration has a different connotation in our context, we use the term state, which can contain other parameters in addition to the position and the heading, e.g. orientation, configuration of landing flaps, landing gear, etc.). A maximum distant landing spot can be reached this way. Often, the targeted landing spot is closer to the aircraft. If it is approached using a Dubins Path, the excess height must be dealt with. Here, we present a method addressing the problem directly, namely finding a trajectory which reduces the excess height over its entire length. Furthermore, it takes spatial and temporal changes of wind and air density into account. Several conditions influence the final shape of the trajectory. For example, avoidance of obstacles and predefined areas is easily achieved. Our method is motivated by kinematic chains, which are used in robotics and computer animation. We extend and modify this principle by incrementally transferring start and end states of the trajectory, modelled as state vectors, into each other. The resulting intermediate states form ends of chain links. To connect initial and final states through the resulting chain, we solve the inverse kinematic problem known from robotics. We extend it by several conditions, which are derived from the flight mechanical characteristics of the modeled aircraft on the one hand and from the desired properties of the trajectory on the other. Using practical examples, we will show the performance of this method, which we have efficiently implemented on off-the-shelf hardware. The method is suitable for systems that assist in the event of engine failures as well as for modeling planned un- or low-powered flights like continuous descent approaches or return flights of space gliders.

Analytical Model for Enhancing the Adoptability of Continuous Descent Approach at Airports

Continuous Descent Approach (CDA) is the flight technique for aircraft to continuously descend from cruise altitude with an idle thrust setting and without level-offs, contrary to the staircase-like Step-down Descent Approach (SDA). Important for air transportation sustainability, using CDA reduces noise, fuel consumption, and pollution. Nevertheless, CDA has been limited to low traffic levels at airports, often at night, because it requires more separation distance between aircraft arrivals and, thus, could decrease throughput. Insufficient attention has been given to helping air traffic controllers decide when CDA may be used. In this paper, we calculate the probability that an aircraft arriving during a particular brief period of time (e.g., 15 min) will need to revert to SDA when the controller tentatively plans to permit CDA for all aircrafts arriving during that time period. If this probability is low enough, the controller may plan to permit CDA during that time period. We utilize an analytical approach and queueing theory framework that considers factors such traffic and weather conditions to estimate the probability. We also provide the number of aircrafts that can be accommodated within the airport’s stacking space using CDA. This number provides insight into whether a particular aircraft may use CDA.

Community Noise Assessment of Hybrid-Electric Aircraft Using Windmilling Drag on Approach

The modeling and assessment of the community noise impacts of a representative hybrid-electric aircraft implementing windmilling motors as drag generators on approach is presented. An increasing desire to reduce emissions caused by aviation has motivated the development of hybrid-electric aircraft that have some degree of their traditional gas-turbine propulsion replaced with electric propulsion. Turboelectric propulsion offers flexibility in the engine architecture that allows hybrid-electric aircraft to be capable of certain advanced operational noise abatement flight procedures. Steep and delayed-configuration approaches are example flight procedures that enable significant noise reductions on approach but require the aircraft to have enough drag for the approach to be stable. Windmilling is an alternative mechanism to create drag during descent and is possible in architectures where the fan is powered by an electric motor. Results examining the potential benefits of representative turboelectric aircraft implementing this controlled drag concept on both delayed deceleration and steeper approaches are presented. The results indicate that windmilling fans are quieter than standard drag-producing devices and can be used to yield significant community noise reductions compared to aircraft performing standard 3 deg continuous descent approaches.

Analysis Of Aircraft Control Input To Produce 3D Continuous Descent Approach (CDA) Trajectory With PY-FME

One of proposed solutions to decrease the fuel consumption of a flight is by optimizing descent trajectory using Continuous Descent Approach (CDA). The focus of this research is to analyze the aircraft inputs used in CDA with several types of trajectories (straight and turning) in 3D (Three Dimensional). The CDA concept used is based on Time and Energy Managed Operation concept where the use of idle thrust is the key point. The research will also analyze the fuel consumption of aircraft in CDA trajectory and compare it with conventional descent trajectory. The methodology on this research is simulation using a Python programming module called Py-FME with Cessna-172 aircraft data. The result concluded that thrust and elevator input have significant effect on aircraft controls to achieved CDA. The research also found that CDA could reduce the fuel consumption by 67.6%.

PBN-Based Time-Optimal Terminal Air Traffic Control Using Cellular Automata

Over the last decade, there has been an increase in air transportation, which has raised awareness to provide necessary procedures to respond to air transportation demands and reduce delay costs. One such procedure, “performance-based navigation (PBN),” currently studied, is expected to increase the airspace capacity based on aircraft's individual performances. This research describes an efficient and expandable model for allocating standard terminal arrival route during continuous descent approach (CDA) that effectively uses PBN requirements. As a case study, we have considered the “Atlanta International Airport” and verified the model's accuracy using real-time traffic data. The model is then used to study mixed traffic behavior concerning each aircraft's navigation capability. We show that our technique helps decrease time separation minima, reducing traffic delays by up to 50% during busy periods. Furthermore, we show that our approach could enhance target traffic flow by as much as 25% while maintaining proper separation minima. Finally, we show that near-optimal control advisory could also be obtained to minimize the target traffic flow's total delay.

DESCENT TRAJECTORY MODELLING FOR THE LANDING SYSTEM PROTOTYPE

This paper gives another view on a method used for aircraft approach and landing phase of flight that enables replacement of standard glideslope. Proposed Landing System is based on Terrain Reference Navigation (TRN) using own created terrain elevation database, based on Radar Altimeter (RA) measurements compared to the overflown terrain. Simulations were performed on a chosen airport (KSC – Košice Airport) and aircraft (Boeing 737-800), where descend procedures was designed based on real airline data in compliance with Initial 4D Trajectory (i4D). Descend trajectory was modelled with EUROCONTROL Base of Aircraft DAta (BADA) performance model as a Continuous Descent Approach (CDA) from proposed merging point to the KSC RunWaY (RWY) threshold. This method was proposed to enhance pilot situational awareness in situations when standard Instrument Landing System (ILS) information could be lost or misleading and without the need of any ground station for successful navigation and guidance to the RWY threshold. Landing System prototype flight test were performed on full mission flight simulator.

Evaluating Fuel Consumption for Continuous Descent Approach Based on QAR Data

Fuel savings are a significant aspect for evaluating the current and future technologies of civil aviation. Continuous-Descent Approach (CDA), as a representative of new concepts, requires a method for evaluating its fuel benefits. However, because of unavailability of the practical operational data, it is difficult to validate whether the previous fuel consumption mechanisms are suitable. This paper presents a unique method for quantifying potential fuel benefits. This permits an easy evaluation for the new procedures without modelling before implementing field tests. The proposed method is detailed in this paper. It derives from the inherent mechanical characteristic of aircraft engine, and utilizes historical flight data, rather than modelling, to predict fuel flow rates by matching flight conditions from Quick Access Recorder (QAR) data. The result has been shown to predict fuel consumption for conventional descent with the deviation of ±0.73%. To validate such method, a case study for our designed CDA procedure is presented. Fuel consumptions in baseline scenarios are estimated to analyse the variable impacts on fuel consumption. The estimated fuel benefits are consistent with the results in the previous field tests. This analysis helps support Air Traffic Management decisions on eventual field test by reducing the validation time and cost.

Framework for Analyzing Aircraft Community Noise Impacts of Advanced Operational Flight Procedures

A framework for analyzing the aircraft community noise impacts of advanced operational approach and departure procedures was developed. In this framework, the altitude, position, velocity, thrust, and configuration profiles of procedures to be assessed are specified by aircraft performance. These profiles are input to the NASA Aircraft NOise Prediction Program, which requires aerodynamic performance and engine state parameters, as well as generates airframe and engine noise throughout each procedure. Generated single-event surface noise grids are combined with population census data to estimate population noise exposure. The framework’s noise estimates agree to within effective perceived noise level of available certification noise data from six aircraft types. Use of the framework was demonstrated on example departure and approach cases to show how it can be used to assess the performance and noise impacts of varying the altitude, velocity, thrust, and configuration for various aircraft. One example shows the evaluation of the noise impacts of an increased thrust departure, in which the thrust and associated altitude were increased on departure. The second example analyzed the noise impacts of altered vertical path and configuration management approaches. These included altering conventional step-down approaches to continuous descent approaches at glide slopes of 3.0–3.2 deg, as well as delayed gear approaches.

Effects of Descent Flight-Path Angle on Fuel Consumption of Commercial Aircraft

In this study, the effects of the flight-path angle (FPA) ranging between 1.0 and 4.5 deg during a continuous descent approach, on certain fuel-related parameters such as fuel flow, fuel burn per 1000 ft of altitude, and specific range, are investigated. The dataset, obtained from Turkish Airlines, includes 4384 eligible flight data records of narrow-bodied commercial aircraft performing 9351 domestic flights between 30 city pairs, across Turkey. The results indicate that the fuel flow is a strong linear function of FPA up to 2.5–3.0 deg for all of the aircraft types, whereas the effect diminishes above 3.0 deg. There is a monotonic decrease of the fuel burn per 1000 ft of altitude with an increase in the FPA, with the trend being stronger than that for fuel flow. Even though the fuel consumption of the descent flight significantly decreases with steeper FPAs, the effect of the FPA on the total fuel consumption of the flight seems not as straightforward as it does when considering only the descent phase. A case study based on this model indicates a U-shaped pattern for total fuel burn with an increase in the FPA, in which the highest fuel saving relative to 1.0 deg of the FPA is calculated to be 14.0% (191 kg) at 2.5 deg of the FPA.

Optimization of terminal airspace operation with environmental considerations

The rapid growth in air traffic has resulted in increased emission and noise levels in terminal areas, which brings negative environmental impact to surrounding areas. This study aims to optimize terminal area operations by taking into account environmental constraints pertaining to emission and noise. A multi-objective terminal area resource allocation problem is formulated by employing the arrival fix allocation (AFA) problem, while minimizing aircraft holding time, emission, and noise. The NSGA-II algorithm is employed to find the optimal assignment of terminal fixes with given demand input and environmental considerations, by incorporating the continuous descent approach (CDA). A case study of the Shanghai terminal area yields the following results: (1) Compared with existing arrival fix locations and the first-come-first-serve (FCFS) strategy, the AFA reduces emissions by 19.6%, and the areas impacted by noise by 16.4%. AFA and CDA combined reduce the emissions by 28% and noise by 38.1%; (2) Flight delays caused by the imbalance of demand and supply can be reduced by 72% (AFA) and 81% (AFA and CDA) respectively, compared with the FCFS strategy. The study demonstrates the feasibility of the proposed optimization framework to reduce the environmental impact in terminal areas while improving the operational efficiency, as well as its potential to underpin sustainable air traffic management.

Study of Point Merge technique for efficient Continuous Descent Operations in TMA

This paper provides a study addressing a methodology for the automatic generation of efficient Curved and Continuous Descent Approach (CCDA) trajectories, supported by arrival flows merging techniques, in a typical TMA, to reduce fuel consumption as well as environmental emissions. The proposed methodology has been applied, through numerical simulations, to an Italian airport, resulting in a considerable fuel saving (up to 30%) with respect to conventional standard arrival routes.

Noise annoyance caused by continuous descent approaches compared to regular descent procedures

During Continuous Descent Approaches (CDAs) aircraft glide towards the runway resulting in reduced noise and fuel usage. Here, we investigated whether such landings cause less noise annoyance than a regular stepwise approach. Both landing types were compared in a controlled laboratory setting with a Virtual Community Noise Simulator (VCNS), using four audio samples: an overflight during a regular approach (2000ft altitude) and three aircraft performing CDAs at respectively 3000, 4000 and 5000ft. The samples at 2000ft and 4000ft were recorded at a countryside road, a 360° photo of which was used for the virtual visuals. The other two CDA samples were derived from the recording at 4000ft. Participants were asked to rate all flyover samples twice while being immersed in the virtual environment. The CDA at 3000ft was rated as most annoying, likely due to a longer overflight duration, followed by the regular descent and then the CDAs at 4000 and 5000ft. As CDAs follow a fairly steady trajectory, it was estimated that they will increase annoyance within an area of approximately 2.5km2, as compared to regular landings. Outside of this area, CDAs may instead result in less annoyance than regular landings.

Potential changes in aircraft noise sound quality due to continuous descent approaches

This paper presents an analysis of how flying Continuous Descent Approaches (CDAs) can affect the quality of sounds that aircraft produce in airport vicinities. It is well known that CDAs present potential benefits in terms of community noise impact with reductions in excess of 5 dBA in peak noise levels. It is however unclear if these reductions in A-weighted level, which is a poor predictor of perceived annoyance, also correspond to an improvement in the quality of the aircraft sounds that reach the residents on the ground. A real comparison can only be made by comparing the sounds an aircraft produces while flying a CDA with a standard approach procedure. A short-range and a long-range aircraft are simulated to fly a standard approach procedure and a CDA with 3, 4, and 5 degree glideslope angle. The noise produced over both approach procedures is then auralized at representative ground locations, and the sounds are analyzed for changes in sound quality. Quantifying the changes in the aircraft sounds in terms of sound quality metrics provides much clearer information regarding how the sound the residents hear has changed, and if the CDAs actually result in an improved sound quality and hence lower annoyance.

Evaluation of Aircraft Descent Profile

Point Merge System (PMS) is a new method for merging and sequencing arrival traffic flows. It consists of sequencing legs, merge point. PMS allows Continuous Descent Approaches (CDAs) which reduces environmental impacts according to aircraft noise, fuel burn and emissions during approach. Aircraft could descend continuously from an optimal position in a low drag with minimum engine thrust. In this study, PMS arrival procedure model will be designed and vertical descent profiles of aircraft will be assessed both in terms of vectoring and PMS. The results show that PMS model achieves more standard vertical descent profiles over vectoring.

How do Continuous Climb Operations affect the capacity of a Terminal Manoeuvre Area

Continuous climb operations are the following step to optimise departure trajectories with the goals of minimizing fuel consumption and pollutants and noise emissions in the airports neighbourhood, although due to intrinsic nature of these procedures, the integration of these procedures need to develop a new framework for airline operators and air traffic control. Based on the BADA model developed by EUROCONTROL, three activities have been carried out: simulation of several continuous climbs for three aircraft types (Light, Medium and Heavy), analysation of different applied separations throughout the climb from the runway up to cruise level and, as third activity, definition of new separation minima to ensure that the minimum separations are not violated with this new procedures along the climb. In this work are presented the results of modelling three continuous climb type (constant true airspeed, constant climb angle and constant vertical speed) and new time-based separations for most used models in Palma TMA, which will be the case-study scenario. Finally, this theoretical analysis has been applied to a real scenario in Palma de Mallorca TMA in order to compare how the capacity deals with the introduction of this new procedure to standard departures, standard departures are understood as a departure with a level-off at a determined altitude and with the possibility to be affected by any ATC action. First outcomes are promising because capacity, theoretically, would not be grossly diminished, which could initially be expected based on previous studies on continuous descent approaches, although these results should be considered cautiously due to the fact that the model lacks several factors of associated uncertainty for a real climb. DOI: http://dx.doi.org/10.4995/CIT2016.2016.3525

Learning Mitigations for Pilot Issues When Landing Aircraft (via Multiobjective Optimization and Multiagent Simulations)

We advocate exploring complex models by combining data miners (to find a small set of most critical examples) and of multiobjective optimizers (that focus on those critical examples). An example of such a combination is the GALE optimizer that intelligently explores thousands of scenarios by examining just a few dozen of the most informative examples. GALE-style reasoning enables a very fast, very wide ranging exploration of behaviors, as well as the effects of those behaviors’ limitations. This paper applies GALE to the continuous descent approach (CDA) model within the Georgia Tech Work Models that Compute framework. CDA is a model of pilot interactions: with each other and also with the navigation systems critical to safe flight. We show that, using CDA+GALE, it is possible to identify and mitigate factors that make pilots unable to complete all their required tasks in the context of different 1) function allocation strategies, 2) pilot cognitive control strategies, and 3) operational contexts that impact and safe aircraft operation. We also show that other optimization methods can be so slow to run that, without GALE, it might be impractical to find those mitigations.

Análise dos benefícios da utilização de procedimentos baseados em desempenho e da utilização de aproximações de descida contínua na rota Galeão-Guarulhos

<p class="Textoderesumo">A introdução dos procedimentos PBN (Performance-Based Navigation) representa a busca pela otimização e melhor utilização do espaço aéreo e a sua implantação é considerada fundamental para os programas de modernização da navegação aérea em andamento em vários países, inclusive no Brasil. A implantação desse novo tipo de procedimento intro-duziu mudanças na operação das aeronaves, na inserção de novos procedimentos para controladores e pilotos e na introdução de sistemas de automação para suporte das operações aéreas e no solo. O objetivo desse artigo é analisar os benefícios da realização de Procedimentos de Navegação Baseados em Desempenho (PBN) e da utilização de Aproximações de Descida Contínua (CDA) na rota Galeão-Guarulhos. O estudo aplicou a simulação em tempo acelerado (fast-time) com o (Total Airspace and Airport Modeler) (TAAM) e considerou nove modelos diferentes de aeronaves. Utilizou como parâmetro de desempenho o combustível consumido. Os resultados do estudo mostraram que os benefícios da aplicação dessas técnicas variam conforme o modelo de aeronave.</p>

Environmental Aspects of Air Traffic Expansion

To expand, aviation must have a reliable, cost effective energy supply, and effectively deal with environmental issues related to energy production, noise, air quality, and climate change. This work describes the challenges arising from the environmental influences of air traffic and presents short-term projections of how the expansion of air traffic will affect global indicators of climate change. The development of air traffic, although it contributes to total greenhouse gases much less than other sources, nevertheless is helping to drive the strong increase in these gases in the atmosphere. This work presents technological solutions to the environmental problems caused by air traffic, primarily by reducing emissions of CO2 and NOx. Emphasis is placed on more efficient fuel consumption during operational segments before and during landing. This work describes collaboration between the Faculty of Traffic Sciences of the University of Zagreb and Croatia Airlines to measure the fuel-saving effects of using the continuous descent approach (CDA). The prospects of implementing CDA in Croatian airspace are discussed.

Optimum Arrival Routes for Flight Efficiency

With the development of aircraft equipment, conventional navigation is the shift from performance based navigation (PBN). As is known, conventional navigation is based on ground-based navigation aids; however, PBN is based on aircraft avionics and performance. In this paper, a new method called Point Merge System (PMS) considered as one of PBN procedures will be introduced. PMS has many benefits related to fuel savings and emission reductions by implementing Continuous Descent Approaches (CDAs). A new PMS standard arrival route (STAR) model will be designed in radar simulation and it will be suggested.