"An agreement in principle is very, very close," says former Tempe city councilmember Barbara Sherman, a long-standing opponent to the project.
Sherman says the runway would increase noise and jeopardize the safety of residents living beneath the flight path. The result, she says, would be a decrease in property values as lenders red-line areas subjected to high aircraft traffic.
"People can't get their money out of their homes and they can't get money to improve them," she says.
While confirming an agreement is near, Tempe and Phoenix officials won't say it's a done deal. "We're closer than we have been in the past, but we still don't have an agreement," says Randy Gross, Tempe's assistant city manager.
Phoenix, which operates Sky Harbor, wants to build the $70 million runway parallel and to the south of its existing runways.
Tempe officials have said they would sue unless Phoenix agrees to restrict air traffic to the existing flight path, which roughly follows the Salt River, and institutes a system under which airlines straying from the path would automatically be fined.
Sherman doubts Tempe's resolve, dismissing talk of a lawsuit as "bluster." Tempe officials say they are worried that once the runway is built, Phoenix and the Federal Aviation Administration will alter future flight paths from the new runway and direct air traffic over downtown Tempe and to the south.
Such a configuration is "the only way to achieve a significant capacity increase at Sky Harbor; it's the only way left," says Tempe's attorney on the case, Elliot Cutler of Washington, D.C.
Cutler predicts Sky Harbor would face air-traffic snarls within three to seven years after completion of the third runway and would be forced to abandon the promise to keep traffic over the Salt River. Fearing such circumstances, Tempe insists on a system that automatically levies fines against aircraft flying outside the existing flight path.
Phoenix deputy city manager Jack Tevlin says the city is prepared to promise that aircraft using the proposed runway would fly within the current flight path. But Phoenix will not agree to a Tempe stipulation that Phoenix automatically assess fines against stray airlines.
"That's been one of the sticking points in the negotiations between the two cities," Tevlin says, adding that the FAA, not the city, has the power to fine errant airlines.
"If the FAA would allow for some kind of sanction system to be put in place, the City of Phoenix would go along with that," Tevlin says.
The FAA has remained outside negotiations, although the agency has granted approval to keeping the flight path over the Salt River. The agency appears to be reluctant to grant Phoenix the power to fine airlines.
"We will entertain recommendations from any community in regard to flight paths," FAA spokesman Fred O'Donnell says. "But our responsibility is to manage flight paths in a manner that is conducive to safety . . . and if safety becomes the issue versus noise, we will err on the side of safety.