SURFACE TRAFFIC MANAGEMENT

In cooperation with the FAA, the National Aeronautics and Space Administration (NASA) is studying automation for aiding surface traffic management at major airport facilities. The surface management system is an enhanced decision support tool that will help controllers and airlines manage aircraft surface traffic at busy airports, thus improving safety, efficiency, and flexibility. The surface management system provides tower controllers and air carriers with accurate predictions of the future departure demand and how the situation on the airport surface, such as takeoff queues and delays at each runway, will evolve in response to that demand. To make these predictions, the surface management system will use real-time surface surveillance, air carrier predictions of when each flight will want to push back, and computer software that accurately predicts how aircraft will be directed to their departure runways.

In addition to predictions, the surface management system also provides advisories to help manage surface movements and departure operations. For example, the surface management system advises a departure sequence to the ground and local controllers that efficiently satisfies various departure restrictions such as miles-in-trail and expected departure clearance times (EDCTs). Information from the surface management system is displayed in ATC towers and airline ramp towers, using either dedicated surface management system displays or by adding information to the displays of other systems.

Parts of the system were tested in 2003 and 2004, and are now ready for deployment. Other capabilities are accepted in concept, but are still under development. Depending on the outcome of the research, the surface management system might also provide information to the terminal radar approach control (TRACON) and center traffic management units (TMUs), airline operations centers (AOCs), and ATC system command centers (ATCSCCs). In the future, additional developments may enable the surface management system to work with arrival and departure traffic management decision support tools.

The surface movement advisor (SMA) is another program now being tested in some locations. This project facilitates the sharing of information with airlines to augment decision-making regarding the surface movement of aircraft, but is concerned with arrivals rather than departures. The airlines are given automated radar terminal system (ARTS) data to help them predict an aircraft’s estimated touchdown time. This enhances airline gate and ramp operations, resulting in more efficient movement of aircraft while they are on the ground. Airline customers reported reduced gate delays and diversions at the six locations where SMA is in use.

TERMINAL AIRSPACE REDESIGN

The FAA is implementing several changes to improve efficiency within terminal airspace. While some methods increase capacity without changing existing routes and procedures, others involve redesigning portions of the airspace system. One way of increasing capacity without major procedural changes is to fill the gaps in arrival and departure streams. Traffic management advisor (TMA) is ATC software that helps controllers by automatically sequencing arriving traffic. Based on flight plans, radar data, and other information, the software computes very accurate aircraft trajectories as much as an hour before the aircraft arrives at the TRACON. It can potentially increase operational capacity by up to ten percent, and has improved capacity by 3 to 5 percent for traffic into the Dallas/Ft. Worth, Los Angeles, Minneapolis, Denver, and Atlanta airports.

One limitation of TMA is that it uses information on incoming flights from a single Air Route Traffic Control Center (ARTCC). Another version is under development that will integrate information from more than one ARTCC. It is called multi-center traffic management advisor (McTMA). This system is being tested in the busy Northeastern area, and the results are promising.

Another software-based solution is the passive final approach spacing tool (pFAST). This software analyzes the arriving traffic at a TRACON and suggests appropriate runway assignment and landing sequence numbers to the controller. Controllers can accept or reject the advisories using their keyboards. The early version carries the “passive” designation because it provides only runway and sequence number advisories. A more advanced version, called active FAST (aFAST), is currently under development at NASA Ames Research Center. In addition to the information provided by pFAST, aFAST will display heading and speed, and it is expected to improve capacity by an additional 10 percent over pFAST.

Airlines can help ease congestion on shorter routes by filing for lower altitudes. Although the airplane uses more fuel at a lower cruising altitude, the flight may prove faster and more economical if weather or high traffic volume is delaying flights at higher levels. The tactical altitude assignment program consists of published routes from hubs to airports 200 to 400 NM away. Based on results of evaluation, it is not expected to be implemented nationally, although it may remain available in local areas.

Beyond using existing facilities and procedures more effectively, capacity can often be increased by making relatively minor changes in air traffic procedures. For example, in some instances, departure and arrival patterns have remained unchanged from when there was very little air traffic, and congestion results when today’s traffic tries to use them. Likewise, arrival and departure procedures may overlap, either because they were based on lower volumes and staffing or because they are based on ground-based navigation. The interdependence of arrival and departure routes tends to limit throughput in both directions.

Separating departures from incoming traffic can simplify the work of controllers, reduce vectoring, and make more efficient use of terminal airspace. In the four corner post configuration, four NAVAIDs form the four corners of the TRACON area, roughly 60 NM from the primary airport. All arrivals to the area fly over one of these “corner posts” (also called arrival meters or feeder fixes). The outbound departure streams are spaced between the arrival streams. [Figure 6-6]

As more and more aircraft are equipped for RNAV, new arrival and departure routes are being created that do not depend on very high frequency omni-directional range (VOR) airways or ground-based NAVAIDs. Shifting traffic to new RNAV routes eases congestion on existing airways. There are already several new RNAV routes in use and many more are being developed.