Flying about 220 feet above ground in Sonoma County’s northwest corner, a PG&E-chartered helicopter gave a loud buzz cut to towering trees that threaten to drop branches on 46 miles of rural power transmission lines.

Moving slowly above the redwoods and Douglas firs of the coastal mountains, the helicopter guided a 30-foot vertical saw — with eight whirling steel blades — over rugged terrain where tree limbs pose a threat to high-voltage power lines from Fort Ross to Fort Bragg.

Trimming 3 miles a day, the Heli-Saw is making its Sonoma County debut as PG&E’s ultimate vegetation management tool.

“We can do in one day what would take a crew of climbers three to four weeks,” said Brian Mulhollen, division manager/safety officer with Heli-Dunn, the Medford, Oregon-based company that works for PG&E throughout its 70,000-square-mile territory.

Approaching a clearing along Tin Barn Road in the Annapolis area Tuesday, the Astar 350 helicopter blasted observers with roaring engine noise and rotor wash as the clattering saw severed protruding tree limbs.

In the cockpit, pilot Casey Blacker peered through a large bubble in his side window to watch the tops of the trees ahead and keep the saw suspended on a pole below in his peripheral vision.

The biggest challenge, Blacker said during a refueling stop in a nearby field, is trimming trees through a canyon when the helicopter descends as the power lines ahead begin rising.

“It’s no fun,” said Blacker, who has thousands of hours of Heli-Saw flight time. “Things like that make more of a mental barrier. You get tense.”

At times the saw stops when it encounters a tree growing within another tree, sending a shudder up the pole and into the helicopter.

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