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    2010 Air Transportation Laboratory Research Symposium Announcement

    June 30th, 2010

    The 2010 Air Transportation Laboratory Research Symposium has been tentatively scheduled for Tuesday, 30 November and Wednesday, 01 December.

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    Clayton Tino

    June 29th, 2010

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    Adan Vela

    June 29th, 2010

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    2008 Air Transportation Laboratory Research Symposium

    April 22nd, 2010

    We are pleased to announce the tentative schedule for the first annual Air Transportation Laboratory Research Symposium. This year’s gathering will also mark the commissioning of the laboratory’s new Aircraft Simulation Facility.

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    En Route and Traffic Flow Management

    April 22nd, 2010

    En Route Speed Optimization to Implement Continuous Descent Arrivals

    Continuous Descent Arrival (CDA) is a procedure defined as a descent from a higher altitude continuously without extended level segments and with engine throttle setting at idle most of the time. While CDAs have been shown to save up to 1000 lbs. of fuel per flight, in turn reducing emissions, and reducing noise over portions of the descent profile, there are numerous issues to address before CDA can become a widespread procedure. Chief among these issues is making sure aircraft arrive at the metering point, the point at which aircraft begin to follow the same flight path to fly CDA, with the necessary time interval. The ATL uses its fast-time simulator to determine the time spacing required at the metering point. However, an aircraft’s flight plan does not often align with the calculated CDA separation. This shortcoming is the current motivation for CDA considerations in en route spacing. By issuing speed changes to the series of flights participating in the CDA procedure during the en route travel portion of the flight, small adjustments to an aircraft’s estimated time of arrival (ETA) at the metering point can be made.

    The above figure shows a screen shot of flights participating in a CDA flight test in April 2007. Although there are only 19 flights shown, one can imagine how difficult it would be to adjust the en route speeds of the flights involved, making sure each adjustment is relatively small yet optimal for fuel burn using manual methods. By incorporating speed changes into an optimization formulation, and also pursuing a more accurate Trajectory Predictor than what is currently available, the minimum amount of speed change necessary to arrange flights to fly a CDA can be found. This en route speed optimization research, in conjunction with the trajectory predictor that provides accurate Estimated Times of Arrival will be tested in the Atlanta airspace during the fall of 2008. Current work on this project will be presented at a conference sponsored by the American Institute of Aeronautics and Astronautics in August.

    En Route Conflict Resolution with Weather Inclusion

    Air traffic delays due to congestion in the National Airspace System (NAS) are a source of unnecessary cost to airlines, passengers, and air transportation dependent businesses. Congestion is estimated to cost the aviation industry, passengers, and shippers approximately $10 billion per year. This cost can be further segregated into a $6 billion impact upon direct airline operating costs and a $4 billion impact upon the value of collective passenger time.

    Delays also have an environmental cost. Because of congestion, aircraft are often forced to fly far from the cruise altitude and/or the cruise speed for which they are designed. Such sub-optimality results in unnecessary fuel burn and gaseous emission that give rise to environmental concerns both globally and locally at ground level. The significant magnitude of air traffic delays presently observed is an indication that the current air traffic control infrastructure is not capable of handing current traffic levels. Given the forecast growth in aviation over the next decade there is an urgent need for air traffic control decision-support or automation tools to address the problem of congestion in the NAS.

    This research develops mathematical models for conflict-free optimal trajectories over a volume of airspace. The Air Transportation Laboratory (ATL) has completed computational studies and demonstrated savings due to proposed algorithms using traffic through Cleveland Air Route Traffic Control Center (ARTCC), one of the most congested airspaces in the US. In addition, the ATL is developing weather models to be included in the simulations so that solutions for aircraft avoiding each other and inclement forecasted weather can be modeled in real time.

    The ATL has determined the environmental benefits in terms of the change in the amount of emissions that are produced by aircraft. The fuel burn is determined using data for aircraft performance and fuel burn that has been made available through an on going nondisclosure agreement with Boeing, and using Base of Aircraft Data (BADA) in the case of other aircraft where this data is not available.

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    Descent and Terminal Area

    April 22nd, 2010

    Continuous Descent Arrivals

    The development of Continuous Descent Arrivals (CDAs) was one of the first main projects of the Air Transportation Laboratory. With increasing fuel prices and a heightened awareness for environmental and noise concerns, airlines and air traffic control are looking at various methods to improve an aircraft’s performance during flight. One such opportunity presented itself during the descent phase of a flight. Currently, aircraft perform what may be termed a ‘step descent’ to the runway. That is, aircraft do not descend constantly during the approach to the runway; instead, they descend from one altitude to another, continue in level flight until a certain point, and then resume their descent to the runway or another altitude. This method is not fuel-efficient since an increase in thrust may be needed to maintain altitude during a level flight segment and by increasing thrust, more noise and pollutants are produced. Such a procedure is in place for many reasons, including airspace restrictions and traffic volume.

    CDAs were developed with the goal of minimizing these level segments and allowing aircraft to descend ‘continuously’ to the runway, without having to level out at a certain altitude. An analogy to such a procedure is driving down a hill in a car, with the foot off the accelerator and letting the car coast down the hill without driving over any flat regions of road. To design a CDA, a fast-time simulator has been created in Matlab and is used to simulate the trajectories that aircraft would take if they flew such a procedure. These trajectories are then provided to air traffic control, who then informs the ATL as to whether the designed procedure fits into current airspace restrictions. If so, the procedure is then flight tested in aircraft simulators, followed by a live demonstration before publication. If not, a redesign is conducted to ensure compliance with airspace restrictions.

    Currently, CDAs designed by the Air Transportation Lab are in use at two airports in the US: Louisville International Airport and Los Angeles International Airport. Results from Louisville have shown that up to 1000 lbs of fuel can be saved per flight along with a substantial decrease in noise over a flight path flown by a B767-300. At Los Angeles International Airport, most flights flying in from the East Coast of the US utilize the designed procedure and along with air traffic control, are very happy with the arrival. Airports currently involved in CDA development include Atlanta’s Hartsfield-Jackson International Airport and San Diego International Airport, with a CDA flight test conducted in Atlanta during spring of 2007 and upcoming tests beginning in August 2008. Delta Air Lines has been a key partner in the development of these procedures, participating in both the flight test portion, and allowing the ATL to use its flight simulators. The fuel saving potential at Hartsfield-Jackson International Airport is enormous due to the number of flights flown by the dominant carrier, Delta Air Lines.

    CDAs are an important part of the Next Generation Air Transportation System (NGATS) of air traffic control. The goal by 2020 is to implement as many CDAs as possible at airports around the US, possibly providing a substantial fuel savings to airlines, as well as alleviating environmental and noise concerns for communities around airports.

    Treating Clusters of Nearby Airports as a Single Entity (Metroplex) to Alleviate Congestion

    In an ideal situation, air traffic flows to and from a given airport would be independent of the traffic flows to and from other airports in close proximity, and the flight trajectories of aircraft would be optimized for economic and environmental efficiency based on factors such as aircraft performance, winds, direction the aircraft is arriving from or departing to, and distance to/from the airport runways. However, in the National Airspace Systems (NAS) of today, where significant airspace is required for a single aircraft path, the traffic flows to and from multiple airports in close proximity can and do interact. This interdependency of air traffic flows of closely-spaced airports defines what the Joint Planning and Development Office (JPDO) terms a metroplex. This research endeavors to agree upon the measurements and conditions that define a metroplex, and a possible example of such an area is the heavily trafficked Northeast Corridor with Newark, LaGuardia, and JFK airports all within close proximity. Once the definition of a metroplex area has been decided, this project will examine the factors that have the greatest impact on on-time performance and find ways to address these factors in the Next Generation Air Transportation System (NGATS), the overhaul of the current air traffic management system. In addition, specific NGATS concepts are being examined in the context of metroplexes, including 4-D trajectory-based operations, performance-based services, and increased environmental awareness using the advanced airport and terminal airspace demand projection, modeling, and simulation capabilities of the team. The results of these studies will be evaluated in terms of the classification scheme described in the previous objective so as to simplify the comparison of various possible NGATS scenarios.

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