Friday, September 13, 2013

Weather patterns behind complaints over flight traffic

BAINBRIDGE ISLAND — Jet engines provide the soundtrack to Jane McCotter’s summer.

Commercial airliners roar over her house seemingly non stop on some days, the Winslow resident says. A few fly so close she can make out the logos on their tails. The noise is deafening.

“It’s become a real nuisance, and a mental health issue,” McCotter said.

According to McCotter and her Lovell Avenue neighbors, airplanes began cruising over their neighborhood in much greater frequency a few months ago. As the issue persisted, they got in touch with City Council members and contacted state Sen. Christine Rolfes. U.S. Rep. Derek Kilmer’s office was also enlisted in the search for answers. SeaTac Airport is now preparing a report on Bainbridge air traffic for Kilmer.

Sea-Tac officials believe the surge in flights reported by island residents is due to a seasonal shift in flight patterns. There are two general patterns airplanes use to approach and depart SeaTac, depending on which direction the wind is blowing over Puget Sound.

On overcast days — about 65 percent of the year — the wind tends to blow from the south. Pilots prefer to land and take off into the wind, so on those days planes land and depart the airport from north to south (called south flow).

On clear, sunny days the wind tends to blow from the north and the pattern reverses. Planes approach and depart the airport from south to north (north flow).

The direction the planes arrive and depart the airport dramatically alters the routes they follow over the Puget Sound region. Neighborhoods that see few planes on a cloudy day could see an upsurge in air traffic on clear days. That happens to be the case for Bainbridge Island.

SeaTac provided the Kitsap Sun with charts showing flight tracks for two 24 hour periods in September. On one day, Sept. 1, planes were flowing to the south. On the other day, Sept. 9, planes were flowing to the north.

On the south flow day, there were only scattered flights over the island. On the north flow day, a steady stream of arriving planes followed a diagonal route across the north end of the island, from Suquamish to Wing Point. A similarly intense stream of planes departed Sea-Tac and flew west over the island, crossing over Eagle Harbor and Illahee, or veering southwest over Fort Ward and Manchester.

Stan Shepherd, manager of Airport Noise Programs at Sea-Tac, said the long, hot summer has created more north flow days, leading to increased flights over Bainbridge Island. Plus people are spending more time outside, where they can hear — and be annoyed by — airplane noise.

Shepherd said it’s common to receive a spurt of noise complaints from specific neighborhoods when wind directions change in the summer. Sea-Tac officials reviewed flight track records over the island and didn’t find any long-term shift in flight patterns.

The seasonal explanation wasn’t satisfying to McCotter. She has lived on Lovell Avenue for five years and said air traffic wasn’t nearly as intense in previous summers. She believes something must have changed in the last year to route more flights over her neighborhood.

Now she feels like her yard is at the end of a runway.

“If I wanted this, I would have bought a house by Sea-Tac and lived there,” McCotter said.

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