Phoenix is changing the rules that govern how tall downtown buildings can be in an effort to better protect flights into and out of Sky Harbor International Airport.
The proposed changes, which are still under discussion, could actually allow taller high-rises in some areas of the city's core while reducing height in others. But it's likely that in most areas, the height of structures will be capped at 40 stories, roughly the height of Bank One Center, downtown's tallest building.
"That really is our controlling factor," Aviation Director David Krietor said. "We don't want to build anything that would make it worse."
The situation poses a unique problem for Phoenix because it marks the first time that two of the city's top priorities have collided.
Sky Harbor, a massive economic development engine, has always enjoyed a privileged position in which its desires came first. But in recent months, Mayor Phil Gordon and the City Council have put billions of public dollars into downtown redevelopment projects in hopes of revitalizing the city's core with hundreds, if not thousands, of full-time residents.
In many ways the effort appears to be working, and that's the problem. Interest in downtown living has skyrocketed, with many developers proposing residential condominiums up to 50 stories high.
All the talk is making the airport nervous.
"All around Sky Harbor is of concern to the Federal Aviation Administration and should be of concern to the city of Phoenix," said Jane Morris, special projects administrator for the Aviation Department.
"Our role at the airport is to look at all of the factors that affect us."
Most of downtown is not in Sky Harbor's flight path. Instead, the concern stems from the fact that some of the proposed developments, if built, could force the FAA and the airlines to change emergency takeoff and landing procedures.
Those procedures are a complicated set of rules and technical guidelines, but the basics are this: On the rare occasion that one of an airplane's engines would fail, there are mandatory actions a pilot must take to land the aircraft safely.
The actions could involve deviating from standard flight paths and are further complicated by such factors as ground and air temperature, aircraft weight and rate of ascent.
An increase in the number of tall buildings around the airport would make it more difficult to get airplanes to the ground safely in emergencies.
The FAA, which works with the airlines to set the procedures, cannot control whether a high-rise is built, but it will make a ruling on whether the building poses a potential hazard.
Such was the situation several years ago when a plan to build the Arizona Cardinals football stadium in Tempe was scuttled because of its height and proximity to the airport.
In most cases, when the FAA rules that a proposed structure poses a risk, cities don't build it. But if a city opts to move forward, the FAA moves in and changes the flight procedures.
"We have to do what is right for the traveling public," said Donn Walker, the FAA's regional spokesman.
That can result in mandates that planes carry less weight in the form of fuel, passengers and cargo, which, in turn, reduces the capacity of the airport.
And that's the one thing Sky Harbor, which is among the nation's busiest airports, doesn't want.
"If there were, theoretically, a lot of high obstacles nearby, we would have to reduce the weight of our airplanes in hot weather," said Carlo Bertolini, a spokesman for America West Airlines. "We'd reduce fuel (and) cargo first, and try to do passengers last. But it would affect our operations."
The current height rules have been in place since 1971 and are severely outdated, officials said.
They allow buildings to range from 250 to 500 feet in the downtown area, with taller structures allowed along Central Avenue, if first accepted by the airport, city Planning Director David Richert said.
And although aviation officials have not worked out exactly what the new regulations will be, they do say that they don't anticipate allowing structures in Copper Square to be taller than about 500 feet, the approximate height of the Bank One Center. The building is the state's tallest.
In some areas of the core, like the Warehouse District, buildings will not be allowed higher than about 22 stories, the approximate height of the Bank One Ballpark and the yet-to-be built Summit at Copper Square condominium project.
That area, ironically, also has a special zoning overlay that is more restrictive than the airport's proposed rules. Those rules state that any building within the district, generally defined as the area south of Madison Street, from Seventh Street to Seventh Avenue, cannot exceed 56 feet, or 80 feet with a use permit. To build a taller structure, a developer needs special variance approval from the Board of Adjustment.
Gordon and others at City Hall are convinced that the proposed changes won't affect the momentum they are trying to create in downtown, even though the regulations appear to have helped scuttle at least one development plan in the downtown area: a proposed 50-story condominium tower on the site of the old Ramada Inn-Downtown.
"They can and they will co-exist," Gordon said. "There's this theory that says, to be a great city, you have to have great downtown skylines. And while I agree that downtown should have the highest buildings in the city, not every building will be, or needs to be, a skyscraper."