Posted: 31 March 2009 | Steve Bradford, Chief Scientist for Architecture and NextGen Development, FAA | No comments yet

Airports play a critical role in the transformation of the nation’s airspace system to the Next Generation Air Transportations System (NextGen). As we move toward NextGen, airports are serving as partners to the FAA in terms of rolling out new technologies and procedures, but they are also a focus for operational change.

Airports play a critical role in the transformation of the nation’s airspace system to the Next Generation Air Transportations System (NextGen). As we move toward NextGen, airports are serving as partners to the FAA in terms of rolling out new technologies and procedures, but they are also a focus for operational change.

In their partnership role, airports provide obvious value in supplying the gates, runways and taxiways that form the bulwark of the nation’s aviation infrastructure. This in turn allows us to better meet the demands for increased capacity, particularly at the most congested airports. But airports are also important in the types of operational changes that focus on aircraft systems and improved air traffic management, which is essential to NextGen’s goal of increasing capacity and efficiency in ways that do not harm the environment.

The NextGen Implementation Plan recognises the essential role of airports by making them, along with aircraft and air traffic management, one of the three major components in the plan. In addition, as NextGen is developing, the FAA and the airport community are moving away from targeting the top 35 airports and moving toward a more holistic approach that considers 15 major metropolitan areas, and all of the airports that are within their regions. This shift in emphasis recognises that these areas have capacity needs that need to be maximised by focusing on specific airports.

The FAA has always recognised that increasing capacity in the nation’s airspace system involves much more than simply pouring new concrete. Building new runways involves an integrated set of commitments. These commitments include airspace design, new procedures, training and navigation aids – thus, runway commissioning becomes the commissioning of new capacity. The NextGen implementation plan has incorporated this spirit in an integrated approach to improving all aspects of future air transportation.

This type of approach is important, because the delivery of new runways and taxiways alone will not be sufficient to meet our NextGen goals. How we maximise the use of each runway is an important question for NextGen. The aircraft and air traffic management initiatives have a focused emphasis on airports, especially maximising the use of runway capacity.

To achieve this goal, as with many other NextGen initiatives, there are two fundamental shifts involved. The first shift is to better integrate aircraft capabilities into air traffic operations, in order to become more aircraft centric. This shift will allow aircraft to execute air traffic management objectives with a minimum of intermediate coordinating and communication.

A key early step in this shift to aircraft centricity can be seen in performance based navigation. Performance based navigation efforts include the addition of area navigation routes to several terminal areas, to improve the flow of traffic into and out of the airports. However, area navigation by itself might not be enough. By adding required navigation performance criteria to the new performance based navigation procedures, increased access and capacity can be achieved. If natural terrain or man-made obstacles limit access to a runway end in circumstances involving lower visibility, such as clouds or rain, the use of required navigation and area navigation routings can provide access to properly equipped aircraft. This type of capability is available to airports of any size.

Efficiency in major metropolitan areas is often limited by the need to manage the flow of aircraft into single streams as they approach multiple airports and runways. This type of approach was necessitated by limitations in the navigation capability of certain aircraft. Under NextGen, modern navigational technology, combined with improved procedures such as area navigation and required navigation performance, will allow these single flows to be split into numerous, ‘de-conflicted’ streams. This will increase capacity in the airspace approaching major metropolitan areas, thus increasing throughput to individual airports and runways. This is of vital importance in airspace between large metropolitan areas such as New York and Chicago.

The use of performance based navigation, however, is not limited to new required navigation routes in terms of access and capacity. The benefits of performance based navigation also include increasing fuel efficiency for aircraft using those procedures, thus reducing the environmental impact of operations. Continuous descent approaches that also involve more direct approaches to the runway surface are also being tested, improved and used more in the U.S. By using continuous descent approaches, aircraft fly a route that has a low fuel, low noise profile from the enroute airspace down to the runway. This in turn lowers the noise level for people on the ground and fuel costs for aircraft operators. At present time, continuous descent approach procedures require increased airspace buffers around each aircraft. Because of that, the use of continuous descent approaches is limited during periods of moderate and heavy demand. Efforts are now underway to develop ‘optimal profile descents’, coupled with air traffic management decision support tools that will allow us to reach our goal of maximising capacity while improving fuel efficiency and lessening harm to the environment. Optimal profile descents are required navigation procedures that are tailored to a wide range of conditions.

One example of the marriage between air traffic management decision support and aircraft procedures is at Louisville, the site of ongoing demonstrations involving the FAA and United Parcel Service (UPS). The FAA and UPS are developing tools and onboard capabilities that sequence aircraft and adjust their routes, to allow them to approach the airport with the correct spacing between them to allow for continuous descent approaches.

Other efforts include the use of what are called ‘tailored’ arrivals to major airports along the East and West Coast, including Miami, San Francisco and Los Angeles. Aircraft flying tailored arrival approaches to these airports over the Atlantic and Pacific have more direct, fuel efficient route paths uplinked to the cockpit as they approach domestic airspace. Thus, their descent lowers fuel burn and is more environmentally friendly.

In order to further optimise the use of these procedures and tools, the FAA is working to break down operational and infrastructure barriers that sometimes occur between high altitude, en route operations and the lower level terminal operations around airports. The purpose is to create a more integrated operation for flights flying through these two types of airspace. The integrated airspace, known affectionately as ‘Big Airspace,’ blend operations between the en route environment and the terminal environment more effectively and efficiently. This will allow aircraft to fly from the top of their descent to the runway surface more directly, with accommodations made more easily during severe weather. This type of blended operation is made possible by advancements in both aircraft and ground technology.

The FAA continues to support the development of a Ground Based Augmentation System (GBAS), which can provide a low cost alternative to Instrument Landing Systems for Category II and Category III operations. We are also looking at how this capability might support a variety of operations, including low visibility taxiing and low visibility landings. This would help aircraft avoid wake turbulence on closely spaced or converging runways.

NextGen will also involve a major shift in the sharing of information by different users in the nation’s aircraft system. Information sharing is not a new goal for the FAA. Through collaborative decision making, for example, the FAA and various users, including the airlines, corporate jets and general aviation, have been able to collectively determine the best way to handle constraints in the system.

Under NextGen, the FAA is advancing to another level of information sharing by rolling out its System Wide Information Management programme (SWIM), which will make information sharing not only easier, but a core part of its business.

System Wide Information Management involves moving the agency’s legacy information application from a point-to-point interface regime, into a service-oriented architecture paradigm that is central to the modern information network. By moving to this new interface structure, the information is not only more easily accessed by existing and new FAA applications, it is also readily available to the community.

Through this new ‘net-centric’ world, supported by SWIM, airport operations can be improved from both the landside and airside perspective. An example of this changing perspective is the ability to share Integrated Terminal Weather System data with the community, in a digital format, that can be integrated directly into their tools and displays. This enhances the weather situational awareness of airlines and airport operators for each location covered by the Integrated Terminal Weather System.

Under NextGen, the FAA also plans to leverage existing technologies to provide additional benefits. One example of this is the Airport Surface Detection System – Model X (ASDE-X), which provides controllers with a display showing the location and movement of aircraft and vehicles on the airport surface.

ASDE-X is an improvement over radar-based surface detection technologies, which sometimes present false targets during periods of fog and rain. ASDE-X, which is being installed at the top 35 airports in the U.S., takes its data from multiple sources and automatically uses the most accurate information.

ASDE-X is now being leveraged to bring benefits not only to controllers but to airline traffic flow personnel. By extending coverage to the ramp areas, airline traffic flow managers using this technology can view screens showing where their aircraft are at all times. This will allow them to more effectively plan operations and coordinate the movement of aircraft from the gate areas to the runways. This will also improve the coordination and scheduling of aircraft in different cities. This capability becomes even more important during periods of severe weather, when operations are disrupted or halted.

Information sharing is just the first step. With the availability of this type of information sharing, true surface traffic management support can be provided. A management system for surface traffic will use the information on active aircraft leaving the gate, or arriving to the airport, to assign runways, runway sequence and taxi clearances. This will in turn, optimise the throughput of aircraft on runways, reducing taxi-out times and delays caused by long lines. The development of programmes such as assigned taxi clearances also aid controllers, by adding another layer of situational awareness beyond the trajectory modelling that is inherent in ASDE-X.

As these tools evolve, there will be more opportunities to better align gate pushback times. This will reduce departure queues and result in savings in terms of time and fuel emissions as aircraft proceed from gate to takeoff.

SWIM supports this type of improved operations by increasing the ease in which information is shared between arrival, surface and departure tools. This is particularly important with respect to departure operations. While arrival management is and can be focused on large airports, departure management involves many more airports. Waiting for a clearance to depart into congested airspace, and/or to a nearby congested airport, affects aircraft at large and small airports.

By using SWIM, air traffic management personnel will be able to better maintain and evaluate the departure queues, by assigning and managing departure slots with greater efficiency. Through the use of integrated tools and displays, they will be able to send departure clearances to appropriate airport and aircraft without the time-consuming and cumbersome verbal coordination often used today.

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