Trees to fall, mandates FAA
Posted: October 14, 2012 – 9:44pm | Updated: October 14, 2012 – 9:53pm
By Dan Schwartz
The City of Kenai and the Federal Aviation Administration will cut more than 2,000 trees obstructing Kenai Municipal Airport flight paths this December.
This phase of the Kenai Municipal Airport Obstruction Tree Removal Project targets 1,213 trees for selective cutting and removal, and 779 trees for partial cutting on city and airport property, Airport Manager Mary Bondurant said. This phase will also clear cut and seed 7.5 acres in the airport's fencing, she said.
FAA's deadline for the project is Sept. 15 of next year.
This phase of the project does not include any private property, City Manager Rick Koch said, but he said a phase a few years in the future will.
"If you're going to have particular kinds of service there are different requirements," Koch said about the Kenai airport.
The most stringent requirement for an airport, he said, are departure requirements. Under those requirements, he said, FAA mandates that nothing can protrude into an airport's flight path.
To determine flight paths, he said the FAA and other regulatory agencies measure 200 feet out from the end of the runway. They then project an "imaginary line" over the land, he said.
"Then based on the kind of service and the kind of navigation aids that are available (to an airport)," he said, "it dictates what the slope is from that point."
For airports that serve Cessna 185 or Super Cub planes, for example, he said FAA requires that the "imaginary line" — or departure surface — rise one foot for every 20 horizontal feet.
FAA requires the Kenai airport maintain a 40-to-one departure surface, according to Kenai airport documents.
"It doesn't matter where you're supposed to land or take off," he said. "If the plane's in trouble it's going to use all of the runway until there's nothing left."
The trees penetrating the departure surface at the Kenai airport will be trimmed by five or 10 feet, Koch said. The majority of some trees penetrate so far into the departure surface that they will be completely removed, he said.
Koch said the city will replace the trees it cuts out completely with trees that do not grow as high.
The city will also "shape" the tops of the trees it trims to improve their aesthetics, he said, acknowledging many residents become upset when trees are cut.
"Many people make decisions or make up their mind based on, 'Well, what's it going to look like right this second,' verses, 'Well, what's it going to look like in a couple of years,'" he said.
In the long-term picture, he said, the branches on the trees the city will cut sections from will grow vertically, partially disguising the old cut.
"It is what it is," he said. "There's an imaginary line going through the air, and we got to try and comply with it."
Dan Schwartz can be reached at daniel.schwartz@peninsulaclarion.com.