July 14, 2008
Air Control Looks to Make a Leap Aviation
By Jonathon R. Ramsey
Even not-so-frequent fliers can see that airline congestion is not getting any better. The Federal Aviation Administration recently declared that two of New York City's three airports - the busiest hub in the world - had reached operational capacity. At the same time, the FAA projected that commercial airline passenger traffic could double by 2025.For salvation, or at least respite, the FAA is looking to what is called the Next Generation Air Transportation System, or NextGen, which will help make the transition from the current Air Traffic Control system from radar-based navigation, to satellite-based navigation, much like the systems installed in many cars.
Said Paul Takemoto, a spokesman for the agency, "The current radar-based system dates back to the Second World War, and this is the next quantum leap in air traffic control, from bonfires to flags to radios to radars to satellites."
The radar signals used by air traffic controllers to track planes are refreshed at intervals of up to 12 seconds - meaning that a controller has only an approximate idea of where a plane is at any given time. Doug Church, head of the National Air Traffic Controllers' Association, said: "Much of air traffic control is about getting planes on the right courses and altitudes and making assumptions about where they're going to be in 12 seconds."
That leads to huge safety buffer zones between aircraft - from three to five miles, or five to eight kilometers, of clear air between planes in good weather, and 10 miles or more when conditions are bad.
The NextGen satellite positioning system, by contrast, will update a plane's precise location every second. By knowing exactly where a plane is, the FAA says it would be able to put planes closer together and so, more planes in the sky.
According to Takemoto: "We had about 769 million people board airplanes last year, and that's expected to jump to one billion by 2016. From a delay situation we are maxed out as far as capacity."
For the FAA, the backbone of the NextGen system is known as ADS- B: Automatic Dependent Surveillance-Broadcast. Planes equipped with ADS-B avionics would broadcast their positions to ground stations, which would relay them throughout the air traffic control system. Ultimately, not only would air traffic controllers know where the planes are, but each plane would know where every other plane is, in the air and on the ground.
The immediate benefit of that increased awareness is a huge gain in safety.
"We rolled it out in Alaska because the terrain caused big problems for coverage," Takemoto said. "We outfitted general aviation aircraft with ADS-B, and it cut the fatal accident rate for those kinds of aircraft 47 percent over the last four years."
Yet NextGen promises much more than that. Currently, because the position of an airplane is uncertain, airliners are forced to make stepped landings: they descend to a given altitude, level out and then descend again when instructed by the tower. With NextGen, "they can make continuous descent approaches so they don't have to throttle back, so they have big savings on fuel and carbon emissions," Takemoto said.
The cargo shipper UPS has been working with ADS-B since 1996, and has the avionics installed on five Boeing 757s at its Louisville hub. A spokesman said that continuous descent approaches saved 40 to 70 gallons, or 150 to 265 liters, of fuel per landing. "It might not sound like much, but project that out to 100 landings per night over 250 to 300 operating days per year. We've also seen a 30 percent reduction in noise pollution, and a 34 percent reduction in NO 2 emissions," he said. Nitrogen dioxide pollution aggravates respiratory illnesses, including asthma and bronchitis.
Also, the radar-based system means flight routes are a connect- the-dots affair - planes fly from radar station to radar station. With satellite navigation and continuous tracking, flight routes can be made more direct, helping to cut fuel use and emissions.
Still, while the benefits of NextGen are clear, in terms of safety, operating costs and environmental gains, installing the system will require huge investments, raising the question: Who should pay for what?
The ADS-B ground network is being paid for and implemented by the FAA, but commercial airlines and other flyers would have to buy new planes fitted with compatible avionics or retrofit old ones.
A vital component of the avionics is a data communications system that allows control towers to send text message instructions directly to planes instead of talking to the pilots. With this system "you don't have issues of frequencies or language differences," Takemoto said. "You have data transmitted from the cockpit to the airplane, sometimes going straight into the airplane computers. It's a much more efficient way of transmitting data than by voice."
The FAA estimates that it will spend $15 billion to $22 billion to install the ADS-B network through 2025, and that it would cost commercial airline companies and general aviation flyers $14 billion to $20 billion through 2020 to retrofit the necessary avionics or buy new planes. The FAA, commercial airlines, and the general aviation lobby, representing business jet and piston-engine flyers, are currently locked in a Congressional battle over how to get everyone to pay their fair share of this investment.
And, once it is all paid for, no one knows how much congestion relief NextGen will really provide. The FAA says it cannot predict how many more planes it may be able to get in the air because it does not know what the new airspace separation standards will be.
Church, the traffic controllers' representative, said the improved tracking system would not change the sheer physics of flying planes. "There are rules in the bible of air traffic control about how much space has to be put between planes, and laws of wake turbulence have nothing to do with using radar or GPS to track them."
Improving air traffic control, moreover, would do nothing to reduce airport congestion. "GPS, for all of its benefit, is not going to help when you have the same amount of runways and ground infrastructure," Church added. "You can put as many extra planes in the air that you want. They still have to line up a minute apart at a super-saturated airport that has a finite capacity to handle aircraft."
Many in the general aviation community agree.
"We really have no problem from an airspace point of view," Alan Klapmeier, chief executive of Cirrus Design, a maker of small private aircraft, said. "The only place we have congestion is around major airports, where it's not 'Do we have enough airspace?' but 'Do we have enough space on runways for airplanes to land?'"
Originally published by The New York Times Media Group.
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