Air traffic sims
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Posted Date: 01/03/2008
Issue: Airside International March 2008
Publication: Airside International
Heavy congestion in the air and on the ground are the main blockages to US traffic flows. The US Government has announced a new policy which has the US carriers’ lobby, the Air Transport Association of America (ATA), up in arms. This would raise the fees on airlines using major runways during peak hours. The ATA has called the policy “nothing more than congestion pricing disguised as an airport fee”. Chief Executive Officer James May added: ”Unfortunately, that does nothing to fix the primary cause of delays – our nation’s increasingly antiquated air traffic control (ATC) system.” Another controversial proposal – to cap flights at New York’s JFK – has achieved a similar reaction. And so the stand off continues. Airlines feel they are being punished for providing commercial service, while airports are often caught in the middle.
This stalemate – both in the industry and in air traffic – is a conundrum which baffles many of the industry’s leading experts, but which a new technology seeks to mitigate. Surprisingly, only a handful of the country’s leading airport operators, and indeed none outside, have taken advantage of the dramatic benefits that this technology brings to bear on the nation’s taxing congestion problems. Despite the ambiguity in its title, FutureFlight Central (FFC) offers aviation leaders a very real and clear benefit. Operated by government agency, NASA, in a dedicated centre called NASA Ames, the technology provides a comprehensive simulation environment that puts to the test airfield layout configurations, before they have been built. It is more than a normal modelling tool, such as those run in fast time by a private consultant. FFC is a full-scale reproduction of an airfield, replete with human pilots and controllers operating in a fully visual 3D air traffic environment. The two-storey facility at NASA Ames Research Center in California, offers a 360º degree full-scale real-time simulation of an airport, where controllers, pilots and airport personnel participate to optimise expansion plans, operating procedures, and evaluate new technologies.
“Airfield planning is probably what it’s been used for more than anything. Also it’s considered a research facility you can investigate future technologies and how they would impact the operation of an airport,” explains Nancy Dorighi, Manager of NASA FFC.
“A lot of human factors research is done here, looking at air traffic controller workload and interface design. As we look to the future of air transportation, NASA is working with other agencies on the next generation air transportation system, looking at greater use of computer automation to provide information to allow controllers to handle more traffic and more closely space aircraft. So FFC simulator is a way to research those concepts and investigate and develop them.”
Under the Space Act Agreement, enacted by the US Congress, NASA is allowed to work for the private sector on initiatives that have mutual benefit for NASA. Such work is on a reimbursable basis; that is, customers reimburse NASA for expenses associated with their project. But despite the costs being kept to a minimum, projects, especially those involving large operation such as major airports, are usually labour-intensive, occasionally involving large numbers in simulation exercises, and usually necessitating much upfront preparation and analysis.
The science
FFC air traffic scenarios encompass the terminal air space and surface of the airfield. The Research Center provides a detailed and highly realistic 3D airport database model displayed on 12 projection screens to provide a 360º out-the-window view of the airport. The 3D airport database is built up from the Digital Terrain Elevation Data, Airport AutoCAD files, high-resolution aerial survey photography and close-up digital photography. The database supports views of the airport from any location, allowing the simulation and playback recordings to show the views from the ATC tower, ramp tower, pilot and ground vehicle operator. Interactive displays support all air and ground positions controlling traffic within a terminal air space. Up to 12 controller positions, eight ramp tower positions and 13 pseudo-pilot positions are networked in real-time. Adacel provides the simulation software. The simulator's aircraft model database contains over 100 3D aircraft models and ground vehicle models. The library collection includes detailed liveries of airlines represented at the airport under study.
FFC continuously updates this collection based on customer needs. During a simulation run, FFC can collect measurements of surface performance for ground vehicles and aircraft, controller/pilot communication, and audio/video observational data. The type of data captured includes not only the entire simulation run, but also statistics such as taxi time, departure rate, runway occupancy time, and non-movement area time. Other data collected may include digital audio recordings of pilot/controller radio transmissions for voice communication analysis, audio recordings of non-transmitted controller-to-controller coordination within the tower cab and video recordings of controller movements using cameras installed throughout the tower cab.
Proven technology
In the case of Chicago O’Hare, which limits arrivals to 88 per hour (compared with the previous volume of 120 per hour prior to 2004 when the cap was introduced) to reduce delays, FFC was used to evaluate a different runway configuration as part of the airport modernisation plan. Dorighi says: “For O’Hare, we simulated two different flow directions depending on the winds and weather. We also ran a clear peak load under visual conditions, and a reduced visibility load where there’s more separation between arrivals, and sometimes different runway configurations depending on the weather.”
Another project was Los Angeles. Dorighi explains, ‘In the case of LA a few years ago, one of the things they were considering was moving a runway over far enough to make a centre taxiway between it and its parallel runway. So we started with the airport the way it is and then modified the visual scene to create that in computer graphics so that it looked like the future work had already been done and then we ran that operation to see how it would play out. Then this year we ran a simulation of an airport which hasn’t even been built yet, and compared two different ways to lay out the runways to see which would be more efficient and safe.” This is Ivanpah, which will be critical to the role of Las Vegas as a major air traffic centre. The main airport, McCarran International, is expected to reach its maximum capacity of 55 million passengers by 2015. Two alternative layout plans are being considered at Ivanpah as a way to alleviate congestion at McCarran and act as a supplemental facility 30 miles south of the city. Explains Dorighi. “The simulation is especially good at confirming or uncovering things that might have been overlooked. In the case of a future airport that’s really the ideal way to use our capability.”
FFC provided the critical evidence. “The airport authority was able to really feel they had some measurable data and evidence to support the plan they wanted and numbers to back it up. It gave them evidence to go forward and modify the design so it’s really best to use this tool before you get your design locked down,” Dorighi says.
FFC also helps in getting consensus and approval for a project to move ahead, such as a new taxiway, which at Dallas Fort Worth (DFW) had reached stalemate in getting approval. DFW wanted to build a new end around taxiway. Dorighi explains: “The airlines actually resisted it for many years. Their perception was it was going to be more taxiing, burn more fuel and cost them more money. What was showcased in the simulation was that, instead of holding between runways like they do now because there’s departures that have to get off, there really isn’t that much more time to get to the gate. Departures are able to take off continuously and not have to wait for any crossings. End-around gives you a way to go around. If you have enough property you can build a route that lets you exit the runway, taxi parallel down around the far end.”
During the FFC simulation, flight simulators were integrated with the tower simulation so the same exercise ran simultaneously from the perspective of a tower and cockpit. In tangible terms a pilot sat in the Ames’ flight simulator viewing the same airfield that was being seen from the tower using the same traffic and talking to the Ames’ controllers in the tower. Moreover, airline representatives from Dallas participated in the study which became a complete demonstration, and a revelation for some. “It was very important to get the airlines to support end around taxiways. They couldn’t have gone forward without the airlines agreeing because airlines end up paying for it indirectly and so the simulation impact was really fantastic during the DFW simulation,” she says. “The net result was that people really developed an appreciation for how much more efficient end around taxiways are going to be especially given the growth of traffic.”
Wider horizons
So why hasn’t FFC been more popular among the nation’s airports? “New technology is always slow to be adopted. If airports for years and years have done their development in traditional ways then it’s a little hard to break through and illustrate the benefit of doing a real time simulation.” Quicker methods using private consultants often results in fast time modelling. This type of modelling is a computer only based simulation of airspace or airfield movements without human interaction. This type of simulation runs faster than real-time to create predictions of taxi times and conflicts. Says Dorighi: “A lot of airports with multiple alternatives will have a consultant or contractor do fast time studies first to narrow their options. Then they’ll do their real time simulation when they’re down to just one or two serious alternatives just to confirm they haven’t overlooked anything or any human factors issues would play into the decision.”
But this is no substitute for real-time simulation involving human participants, believes Dorighi. “We are really the only facility that can set up a big airport of heavy traffic operation and simulate it,” she says. “I think it isn’t being exploited enough. But we’re slowly making inroads there especially for the larger more complex operations.”
Despite being a US government funded project, FFC is also available to overseas airports. “We haven’t done any work from outside the US, but that’s not because we wouldn’t – it’s only because we haven’t been asked to. I think if that work had some mutual benefit for NASA that we would do it. So I think we are open to doing work for any other country.”
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