Southwest Airlines Flight 658 pushes back from the gate and shows up as a blip on a radar screen in the tower at Dulles International Airport just before 7:30 a.m. Wednesday.

For the next 90 minutes, the plane will move as a blip across one radar screen after another, as a system introduced in the 1950s tracked and guided its progress to Chicago.

The safety of the Boeing 737 and 118 passengers will fall to at least 10 air traffic controllers and their radar displays — at Dulles, and in Warrenton, Leesburg, Indianapolis, Aurora and Elgin, Ill., and at Midway Airport.

The limitations of that radar, which sweeps like the beam of a lighthouse, will require Flight 658 to fly miles out of its way and burn about 67 additional gallons of jet fuel. Because a jet plane can fly more than a mile and a half in the time it takes for that radar beam to come around again, the plane must be kept three to five miles from the nearest aircraft.

The pilot probably has a more sophisticated guidance system in his car than in his plane.

Now the Obama administration has embarked on the single most ambitious and expensive
national transportation project since completion of the interstate highway system: a program called the Next Generation Air Transportation System (NextGen).

The NextGen concept sounds simple: Replace an air traffic system based on 60-year-old radar with a satellite-based Global Positioning System (GPS) network that would be far more versatile and efficient. In reality, it is an extraordinarily complex undertaking, threatened with delay by airline fears that the government will not deliver the system in time to justify their expenditures.

NextGen demands the largest investment ever made in civil aviation: between $29 billion and $42 billion for equipment, software and training by 2025. The cost would be shared by a federal government struggling with budget constraints and an airline industry that has been drained by years of recession and high fuel prices. Those tensions over funding threaten to slow the launch of NextGen, despite near-universal support for the program, and delays could prove costly.

NextGen is touted as the antidote to gridlock in the air travel system, forecast to be serving 1 billion passengers a year by 2021, up from 713 million last year.

With GPS precision, planes would be able to travel packed skies in safety at much closer distances. They would be able to fly direct routes, unlike in the current system, which relies heavily on flying to waypoints before turning to a final destination.

Direct routing would save airlines billions in fuel costs and minimize pollution. It would permit far more precise choreography of planes at airports, reducing the amount of fuel wasted waiting for takeoff or burned because planes waiting to land are ordered into holding patterns.

For passengers, NextGen would cut flight delays, eliminate time spent on the runway waiting to take off, shorten the flight time once airborne and bring fuel savings that promise to keep ticket prices lower.

“It’s going to be like pulling out of your garage and all the traffic lights are green,” said Marion C. Blakey, president of the Aerospace Industries Association and former administrator of the Federal Aviation Administration. “It would be great if we could get the traveling public to understand it now, because it’s going to be too late to scream about it when the airports are packed.”

Advocates say the United States will lose its competitive edge in the global transportation economy unless the government pumps $11.5 billion into the program in the next seven years and airlines pony up an additional $7 billion to $10 billion. The cost of delaying the system even by less than five years has been calculated at $20 billion.

Precise choreography

The very business of getting aloft — the time that passengers know as the minutes between the “buckle your seat belts” order and “you are free to move about the cabin” — is an intricate choreography between controllers and the cockpit.

“Two seventy on the heading, Southwest 658 going to departure,” the pilot says just after liftoff from Dulles, repeating the compass direction given by the Dulles tower.

Then he tells a controller based in Warrenton that he’s climbing.

“Potomac departure, Southwest 658, passing [1,800 feet] for 3,000, heading 270,” he radios.

The new controller tells him to keep climbing to 5,000 feet and maintain that altitude. That keeps him 1,000 feet below flights heading to land at Dulles. When the plane reaches a waypoint known as “Blues,” a new controller takes over and orders Flight 658 to 12,000 feet.

When Flight 658 reaches another waypoint, over Linden, Va., the pilot is told to head for 17,000 feet. Then he is handed over to a new controller, on a different radio frequency, who takes the flight to 27,000 feet before handing over to yet another controller who ultimately guides the plane to its 40,000-foot cruising altitude.

Now, “you are free to move about the cabin.”

If all that sounds complicated and open to human error, one goal of NextGen is to replace almost all of it with new technology, much of it in the cockpit.

Can the FAA deliver?

NextGen has virtually no credible enemies — not in the administration, not on Capitol Hill and not in the airline industry.

But the seemingly simple concept is layered like an onion with complexities. In addition to demanding an enormous investment, there is a confluence of history and technology that creates a hurdle to progress.

Airlines fear that the FAA will not meet its timetable for creation of the network of ground-based stations and satellite links that will make it all work.

“The FAA’s track record on deployment hasn’t been good,” said Russ Chew, a former airline executive and former FAA chief operating officer. “The FAA could be perfect in meeting NextGen deadlines, but [private investors] are looking at past history.”

Michael P. Huerta, the FAA deputy administrator who was given charge of NextGen after an internal shake-up this year, said he is well aware of that. “How can they be sure that FAA will deliver on its commitments? That’s a fair question,” Huerta said.

As for evidence of the rapid pace of technological advancement, one need look no further than GPS. The technology is advancing so quickly that some car buyers opt against the factory-installed unit for fear that it will be outdated in a year or two.

Airlines have the same issue.

“If I go first, I’ll have to bear the cost of updating the software, and when [NextGen is] turned on, I’ll have the oldest, most obsolete systems out there,” Chew said.

In addition, the FAA must clear through a jungle of procedures and retrain 15,475 air traffic controllers to deal with a system that will entirely replace the old one.

“A lot of the tough stuff is new procedures, is human-machine interface and human factors, moving from an air traffic control mind frame to an air traffic management mind frame” that puts greater responsibility in the hands of pilots, said Bobby Sturgell, former acting FAA administrator.

Congress has tossed more uncertainty into the mix by extending the current FAA funding plan 20 times rather than approving a comprehensive long-term spending plan that imposes strict NextGen deadlines on the agency.

“NextGen is threatened,” Chew said. “Everyone knows it. The FAA budget is under pressure. Even they will say that NextGen is on track, but it’s not.”

JetBlue, with $4.2 million in federal funding help, and Southwest Airlines, with federal incentives, have installed some of the technology, but other airlines are reluctant to move ahead.

“Absolutely I’m concerned about the schedule,” said Gary Kelly, chief executive of Southwest, which has spent $94 million on NextGen. “I’m concerned that we don’t have metrics in place to measure the progress. Any investment, any project, has to be evaluated based upon the risk of the return, and I’m not going to argue with you, this is a very high risk-return, because we’re not in control of the benefits.”

Radar’s limitations

Although bells and whistles have been added over the years to the system that now manages 13 million flights a year, air travel relies on radar developed during World War II and a corps of air traffic controllers who monitor radar screens and relay instructions to pilots.

Radar comes with limitations. It doesn’t cover oceans or swaths of the country where mountains get in the way. Planes have to be kept three to five miles apart because they become a blip on the radar screen only every 11 seconds.

To keep planes safely separated at cruising altitudes, the nation is crisscrossed with a network of defined routes that look just like that map in the plane’s seat-pocket magazine that shows where the airline flies.

There are hubs in the sky — picture a traffic circle at 37,000 feet — and when airplanes reach them, they receive instructions to change course to another hub or their destination. If all the NextGen components were in place, pilots and air traffic controllers would receive precise position reports once every second. Pilots also would know the location, speed and direction of every plane around them, something they now get less complete information on by radio from controllers.

Precision and the superior coverage of GPS, including for transoceanic flights, would allow direct flights. Overall, the FAA estimates the system would cut delays by 35 percent, save about 1.4 billion gallons of jet fuel and cut carbon dioxide emissions by 14 million tons in the next seven years.

With Europe and Asian economic competitors developing more efficient flight management, and with a huge export market to be exploited by U.S. firms if they can dominate the field, the cost of doing nothing or delaying implementation has been calculated in the billions.

“What’s it going to cost us not do do this?” FAA Administrator Randy Babbitt asked rhetorically at a recent conference. “Can we afford not to do this?”

Babbitt says the program is on track and under budget to meet key midterm program deadlines in 2018.

“We have a number of key programs that are progressing,” he said. “Sure, we’ve had setbacks, but we’re making our [deadlines].”

Confidence in the FAA’s ability to deliver on time was shaken in December when the Transportation Department’s inspector general said that software problems had put the FAA behind schedule and $65 million over budget in deploying a $2.1 billion computer system intended to become the backbone of the system for controlling planes at altitude.

The En Route Automation Modernization system is intended to plug into some of the NextGen components, and the inspector general, in a report to Congress, warned that “problems with ERAM will have a cascading effect on FAA’s NextGen efforts.”

Stumbling over installation of that computer system — relatively simple compared with NextGen — at 20 FAA centers raised concerns about how effectively the agency can manage the transition to an entire new aviation management system.

“I think we have a couple of important deadlines to hit over the summer, and I’m confident we’ll be able to achieve the rollout we’ve set over the next couple of years,” Huerta said.

Direct-flight fuel savings

Humming along into the Midwest, Flight 658 is headed for Chicago, but not exactly. The pilot flies west to the middle of the West Virginia panhandle and turns west-northwest to a point in western Ohio. There he turns the plane northwest, and later west, before turning northwest again in a stair-step fashion toward Chicago.

What’s going on?

Two things: He’s flying from one ground navigation station to the next, to Rosewood, Ohio; Fort Wayne, Ind.; Goshen, Ind.; and Chicago Heights, Ill. At the same time, radar control of the flight is being handed from one air traffic center to the next — Washington, Indianapolis, Chicago — while at cruising altitude, and then to the Chicago approach control facility and, finally, the Midway tower.

The direct Dulles-to-Midway route is about 576 miles; the route required by using radar and ground stations is 622 miles. Wind and weather affect how much fuel a plane burns, but based on the rate at which Flight 658 burned fuel Wednesday, those additional 46 miles would suck down 85 gallons of fuel. Multiply that by 365 days, and the direct-flight fuel savings for Southwest 658 adds up to more than 31,000 gallons a year.

A host of obstacles

There are many issues that make airline executives hesitant.

Developing a vast network of new airplane routes to take advantage of NextGen is like building thousands of new superhighways: They all will go over a lot of back yards, and some of those homeowners will fight back.

“Noise is a phenomenal issue,” said Blakey, the former FAA admini strator who recalled how her office phones lighted up when neighborhoods got agitated over proposed new routes.

When the FAA began to create new routes in airspace over New York City, New Jersey and Philadelphia, a full environmental impact study and ensuing lawsuits took eight years and cost $17 million to resolve, according to the Air Transport Action Group , an environmentally focused aviation organization. Most reviews require far less time and expense, but the need to do thousands of them will take time.

Many of those new fuel-and-time-saving routes may have to be negotiated with the military, which restricts air traffic in about 11 percent of U.S. airspace.

The ability to handle a vast increase of planes in the air must be met with new airport capacity, and a Government Accountability Office report last year warned that “building additional runways can take as long as a decade or more.”

The heart of NextGen is a GPS-dependent device commonly known as ADS-B (Automatic Dependent Surveillance Broadcast). Installing it in cockpits is estimated to cost airlines between $2.5 billion and $6.2 billion.

Until an estimated 80 percent of planes are equipped with ADS-B, the system won’t work as intended. The FAA has mandated that airliners be equipped with ADS-B transmitters by 2020. Sturgell, the former FAA official, recalls the last FAA mandate: that airlines install a cockpit collision warning system commonly referred to as TCAS (Traffic Collision Avoidance System).

“They didn’t equip until the end on TCAS either,” said Sturgell, now an executive with Rockwell Collins. “It’s not reasonable for us to expect all airlines to invest today when the program is just starting to get rolled out. So the FAA needs to get it in place, needs to change some of these procedures so that it is a benefit to airlines.”

Incentives for airlines

Making the business case that will persuade airlines to take the financial plunge is at the core of the debate.

“If we can figure out how to get the incentives out there to get people to equip their fleet, we can speed the process,” said Rep. Thomas E. Petri (R-Wis.), chairman of the House Transportation and Infrastructure subcommittee on aviation.

The single biggest incentive to airlines would be persuasive evidence of an immediate return on their investment in fuel savings and fewer delays. One suggestion has been to allow NextGen-equipped planes to land and take off first. Given that a jetliner can burn through $1,000 in fuel in less than half an hour, circling the airport in a holding pattern becomes an expensive proposition.

With most U.S. airlines operating in the red, Chew, the former FAA official and airline executive, said few will take the investment leap unless the government has more “skin in the game” than promises and deadlines. He is leading an investment group that proposes to lend the airlines money to equip their planes, with a repayment plan that is deferred until the FAA delivers the system. The key is that the federal government must agree to make loan payments if the FAA misses its deadlines.

“If the government okays loan guarantees for equipage, it would jump-start the process,” Chew said. “The airlines are not going to want to make any kind of payments until the FAA is ready to deliver. If they don’t deliver by 2018, then the airlines are off the hook for these payments.”

Chew says the FAA and Congress have been receptive to that form of loan guarantee, but without committing to it. With Congress in a cost-cutting mood, loan guarantees may provide a viable alternative to slashing a program that virtually everyone supports. Blakey, in a speech to the Aero Club of Washington on Thursday, urged Congress to approve the Obama administration’s request for $1.24 billion to fund NextGen in fiscal 2012.

“You start doing what some in Congress are suggesting, cut it by 15 percent,” Blakey said in an earlier interview, “and you push it out to 2022. You are really costing the economy in a very calculable way, $20 billion. This is a real cost, not some speculative benefit.

Gliding to benefits

Almost an hour after Flight 658’s takeoff from Dulles, an air traffic controller has found a way for it to nip 10 miles off its planned route. Descending to 28,000 feet for about three minutes, the pilot is then ordered into a continuous glide to 10,000 feet and a second continuous glide to the runway.

The glide saves fuel, and Southwest can do it at Midway because of a deal it struck with the FAA. In return for installing elements of NextGen in all its planes, the FAA equipped 11 airports that are key destinations for Southwest with the technology to use it.

Ninety minutes after takeoff, Flight 658 touches down at Midway and rolls to Gate B14.