The challenge of trying to keep the nation's air traffic on time is a complex problem, one that is easy to oversimplify.

Two weeks ago, I may have done that when I analyzed the David-vs.-Goliath fight between Delaware County and the city over Philadelphia International Airport's dream of building a new runway to try to improve its on-time performance.

As you may recall, Tinicum Township and Delaware County sued the city last month in the county Court of Common Pleas, contending that Philadelphia was required by state law to negotiate with its neighbors over expansion plans.

Two-thirds of the airport is in Tinicum, and the suit asks the court to force the city to get consent from Tinicum and the county before buying any land to put a new runway along the Delaware River and make other changes to the airport layout.

More than anything, suburban leaders say, they are looking for more respect and consultation from the city. If I heard noise daily from airplanes taking off from the airport, as many county residents do, I might feel the same way.

But in recounting some reasons that Philadelphia and the Federal Aviation Administration favor expanding the runways, I didn't outline the potential magnitude of the air-traffic congestion problem and the multifaceted approach that experts say it will take to deal with the matter in the years ahead.

Roger Moog, the aviation planning manager for the Delaware Valley Regional Planning Commission, reminded me in an e-mail and an hour-long conversation what we're up against. So did another longtime source of knowledge for me about the airport and the FAA, consultant Richard Golaszweski of GRA Inc. in Jenkintown.

These gentlemen noted that no matter how much some may wish it otherwise, air traffic in this country and worldwide is expected to grow over the next 15 years. Passenger counts have roughly tripled since the airline industry was deregulated in 1979.

The FAA can be criticized for many things, but its projections of traffic growth have been fairly accurate.

Certainly, since mid-2008 the recession has slowed the long-term growth of air traffic, just as previous recessions have. Our economic problems and the airlines' subsequent cuts in flights mean that the number of passengers will be down about 8 percent this year from 2008, the FAA said in its 2009-2025 forecast, issued earlier this year.

But the FAA, basing projections on the best guesses about future economic growth, says to expect U.S. airline traffic to grow at an annual rate of 3.4 percent, reaching more than a billion passengers by 2025, compared with an estimated 700 million this year.

Because of the recession, the 2025 forecast was reduced from a projection two years ago of 1.2 billion passengers by 2020.

Dealing with a billion air travelers a year will require numerous applications of new technology, including using satellites and GPS-equipped planes to replace the World War II-era radar system now used for air-traffic control.

This so-called Next Generation control system will take decades and billions of dollars to build, and when it will really be helping to alleviate the problem is anyone's guess.

Another good idea for reducing air congestion, greater use of high-speed trains to replace planes on shorter routes, also would take decades and billions of dollars.

So other than pouring more concrete for runways, what else could be done in this region to alleviate congestion and try to change Philadelphia's reputation as one of the nation's most delay-prone airports?

Moog is disappointed that there isn't greater use of the other airports in the region, in the Lehigh Valley, Atlantic City, and elsewhere, to take pressure off Philadelphia and make better use of the public's investment in those facilities.

But under a deregulated airline system, the FAA has little power to make the airlines use smaller airports. In tough economic times, airlines retrench, and the first places to suffer are the smaller spokes from hub airports.

"We can't force change from the airlines' current business model, which is to pack them into the hubs," including Philadelphia, he said.

Golaszweski reminded me of another problem. Unless cities and regions formed regional authorities years ago to manage transportation, as the Port Authority of New York and New Jersey does, the cities that own major airports are loath to give up control of them.

So Philadelphia isn't the only city that has resisted forming a regional authority that might be able to provide incentives to airlines to spread out their traffic to more than one airport.

Even if we had a regional agency running things, it might do as the New York authority did last year, joining with the airlines to stop the federal government from limiting traffic with slot controls at the most congested airports.

So we have quite a puzzle on our hands, don't we?

We shouldn't expect major progress in relieving air-traffic congestion for years to come, unless Congress and the president were to shock us all and decide that regulation of where and when airlines can fly is an idea whose time has come again.

Contact Tom Belden
at 215-854-2454 or tbelden@phillynews.com.