AUBURN, Wash. (AP) -- Two couples flew in this spring for a concert at the White River Amphitheater. One woman chartered a plane from Santa Barbara, Calif., to gamble at the Muckleshoot Casino. A businessman from Salem, Ore., arrived by air every weekday morning for a consulting job in Kent. And a woman from Eugene chartered a flight to get cancer treatment at Auburn's hospital.
Customers like these are helping make Auburn Municipal Airport soar as the fourth-busiest in the Puget Sound region.
Now city leaders are planning aggressively to expand the centrally located airfield in the next few years, which could lure more business from other airports in Pierce and King counties.
''I really think it's a diamond in the rough,'' said Jamelle Garcia, who manages the 88-acre, city-owned airport. ''I want it to reach its potential.''
In light of Southwest Airlines' plans to move and build a $130 million terminal at Boeing Field in Seattle, Auburn officials already are talking with King County and with pilots about shifting some small aircraft parts suppliers and corporate planes from the county airport.
The city also is talking with King County Metro Transit about buying the Park&Ride lot on 15th Street Northeast to lengthen the runway to handle more small turbine jets. And there are plans to construct a three-story building with offices, shops and a restaurant at the south end of the field. The structure - about half the size of a Fred Meyer store - would create a new airport gateway.
Garcia says many people are surprised to learn Auburn even has an airport - let alone the busiest behind Sea-Tac Airport, Boeing Field and Paine Field in Everett.
''We're kind of the best-kept secret,'' Garcia said.
Not to pilots, however.
Auburn Municipal Airport - also called Dick Scobee Field in honor of the fallen Challenger astronaut from Auburn - has 450 takeoffs and landings a day. Garcia said it could add up to another 78 a day and grow by up to nearly 20 percent.
Besides being home to 277 planes, the airport also has a flight school and a maintenance shop.
About 170 hangar bays - many of them condominiums selling for $50,000 and up - are almost all sold or leased. There's room to grow on 3 acres to the south and 23 acres on the west side of the airport.
The main draw is the central location, say pilots and rival airport managers. It's close to Seattle and Tacoma but away from the worst traffic bottlenecks, and it's convenient for the growing populations in South King and Pierce counties.
On a sunny summer day, a steady buzz comes from small planes descending over fast-food restaurants and the Park&Ride lot to touch down on the 3,450-foot-long runway.
Pilots flying propeller-driven planes for recreation and business already create steady traffic. Nearly two-thirds of Auburn's business comes from planes not based at the airport, Garcia said.
The facility is self-supporting, generating about $500,000 a year.
How quickly it expands depends on how soon companies invest, said Auburn Mayor Pete Lewis. Grants from the Federal Aviation Administration could help.
Lewis said the airport, which opened in 1969, is a community asset.
''They have to have a better product to survive,'' Lewis said. ''If we do these improvements, it allows better access to a business community we would like to have in Auburn.''
Other airport managers have heard about Auburn's plans but say they aren't worried.
Mike Esher, administrator for Pierce County Airport-Thun Field in South Hill, said Auburn's expansion wouldn't significantly hurt his growing business.
''It wouldn't concern me at all,'' Esher said. ''We have a waiting list to sell hangars.''
Overall, the aviation industry is still rebounding from the Sept. 11 terrorist attacks. Flying a plane has become more affordable, Esher said. A used Cessna propeller-driven plane costs as little as $50,000.
''Recreational flying now is probably not much more expensive than owning a 35-foot-long sailboat,'' Esher said.