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SunBreak | Will new flight paths bring quieter Seattle skies?

Back in June 2012, the FAA launched a study called “Greener Skies Over Seattle,” as part of its larger NextGen initiative to upgrade air traffic control nationwide. (If you follow the news of such things, you may already have heard about previous tests without passengers, in the summer of 2010.)

Now, if you live below a flight path on the north and south SeaTac approaches, you might be noticing a change in the skies above you. In theory, this is all for the better, as the traffic control upgrade is supposed to reduce jet noise, save fuel, and in the future allow a greater volume of arrivals and departures, even in limited-visibility conditions.

For the next six months, the FAA will be analyzing real-world flight data from Greener Skies, in part to continue to optimize, and in part for an environmental assessment process. To provide feedback, make plans to drop in at a public meeting:

  • September 5, 2012, from 6:00 to 7:30 PM: Federal Way Library, 34200 1st Way South, Federal Way, WA 98003
  • September 6, 2012, from 6:00 to 7:30 PM: Ballard Branch Library, 5614 22nd Ave. NW, Seattle, WA 98107

You can also email by September 14, 2012. The final assessment should be published by the end of the year. (Further study will be conducted in 2014, 2018, and 2023.)

The airline leader in this is Alaska Airlines, which thanks to more challenging Alaskan conditions, has been leveraging technology to fly in and out of airports with satellite-guided precision since the mid-1990s. Together with its subsidiary airlines, Horizon, Alaska carries about half the air passengers at SeaTac (the airport served some 35 million passengers in 2011), and its aircraft are already equipped to implement the alphabet-soup advances the FAA plans: RNAV, RNP, and ODP.

That said, any airline flying more recent Boeing 737s, 757s, and 767-300s or the Airbus A-319, -320, and -321 will likely be able to use the new instrumentation procedures (Canadair’s CRJ-700 and -900 regional jets make the grade, too)–93 percent of SeaTac jets should fall in this category. Traffic from the north, south, and west is most affected:Cranky Flier notes that, “For Alaska, that means 75 percent of its traffic (and around 60 percent of Horizon’s traffic) can take advantage” of the new flight paths.

The tricky part is to integrate satellite-guided approaches with controller-handled approaches. At SeaTac, that means that jets will be cleared for an autopilot approach from as far as 40 miles out (northwest approach) and 140 miles out (southwest), giving controllers time to slot in other planes that need their guidance.

Planes using the optimized descent profile (ODP) will make a single, long “gliding” descent, all at flight idle, which is where the fuel savings come in. Overall, the impact is not huge–it’s expected to provide a one-percent reduction in fuel usage. But airlines would prefer not to spend the extra money if they can help it, and it does reduce fuel usage (and its concomitant pollution) specifically over Seattle.

They also begin that glide at altitude, so they can remain higher up (with less noise making it down to rooftop level) for a longer portion of their approach. Residents close in to SeaTac won’t likely notice much difference in noise-per-jet, but outlying areas might. The new paths are expected to cut 14 to 26 miles of currently dog-legged southern approaches, but will add to others.

A new, shorter western approach that takes southern arrivals over Elliott Bay, rather than over north Seattle, will have an obvious impact for north Seattle residents. But the FAA’s draft assessment (full documentation here) also says:

The new procedure is expected to increase slightly the number of flight miles flown for some aircraft, taking them farther north than at present. Instead of overflying northern portions of Kitsap County as now, more of that traffic would approach the runways from over Hansville and Puget Sound south of Island County.

The ramifications of the changes are a little mind-boggling, if you want to know what precisely the effects will be. Really, only time will tell. Consider that so much depends on which way the wind blows:

Because aircraft operate most effectively into the wind, and winds are always reported in the direction from which they are blowing, September is the most likely month to experience the use of northerly-oriented runways 34L, 34C, and 34R. Other months, the winds would tend to favor use of southerly oriented runways 16L, 16C, and 16R.

The SunBreak is an online magazine of news & culture. A conversation about the things on Seattle’s mind.

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11 thoughts on “SunBreak | Will new flight paths bring quieter Seattle skies?

  1. I don’t see one difference between the current and proposed maps for both the Northbound and Southbound paths. If this were a Spot the Differences game in the newspaper, I would think that the game was cheating me. I’m pretty sure they’re identical.

  2. i’m proud of CHS for covering this extremely boring story. i’m also unconvinced that the “new” and “proposed” maps are any different in any way. it would be nice, though, if our friends in the south sound who are affected most of all had a bit of relief from aircraft noise.

  3. The maps posted are confusing but I understand the concepts being tested.

    As an example, I’m flying from LAX to SEA the plane shouldn’t have to swing around the University of WA to make its landing. It should simply fly directly into SEA without making drastic turns. I never got why this is done as it tacks on extra time. I fly often and it’s common for planes to circle around airports, kinda frustrating.

    I know there are a number of safety factors that come into play and planes need to be spaced out but there has to be a better, more efficient way. Hopefully the models prove out.

    As for the noise factor, I can hear a plane as I type this and realize its the price I pay to live in city and have an in city airport. A lil noise which I can tune out is better than the alternatives.

  4. The differences are easier to see in slideshow format — however I’m wrestling with Flickr code to make titles/captions show in slideshow format. Sorry for the issues.

  5. Yeah, just fly on up and straight into the runway. Why even have air traffic controls. Just let planes land whenever they get there.

    Damn the maneuvers, head straight at ’em.


  6. Olive on Nrth Beacon hHill and have been having a harder time sleeping at night during the midnight landing push at the airport. I figured the noise just seemed extra loud because the windows were open. Now, I know I’m not crazy for noticing more noise.

  7. Oh no. You are correct. There s a lot more noise. There are several people attending these meetings that want to stop the unfair flight allocation over South Seatle. I suggest you join us at the meetings to share your experiences.

  8. As the author points out, it depends on the wind, hence the reason you can’t just drop on down since you are flying northbound anyway.

  9. When the wind is blowing from the south (ie almost all the time), the noise over Cap Hill is out of control. Between about 7pm and 8pm and again between 10pm and 11pm it seems like there’s a plane roaring overhead every 2-3 minutes, straight over the top of the most densely populated neighborhoods in the city. Good luck trying to relax outside, or inside with the windows open. Here’s hoping the new system reduces traffic overhead.

  10. I read this article and didn’t understand a lot of it. The diagrams on Flickr were so small I could not sense of it. I do, however, live just under the flight path that has very heavy from 5:30 to 7:00 pm. Last night I recorded planes going over my house beginning at 5:28 pm. Until 7:00 there was a plane about every 2 to 5 minutes. It was a lovely evening and we were trying to eat out doors but the planes made conversation next to impossible.
    We also are subjected to flights as early as 4:30 am.
    It may be apparent that I live on Capitol Hill. Why can’t the flight pattern be moved toward the freeway or Elliott Bay.
    As I am writing this, I hear the planes continue their nightly routine and I can’t again enjoy the outdoors. It seems to be just in the last 6 months that the planes have become such as noise problem.
    What is going to be done to correct this problem?

  11. Planes come and go in a matter of seconds. Perhaps it’s because I’ve lived under flight paths my whole life, but it never seems to be a problem. Reminds me of post-9/11 when it was so exciting to hear planes in the sky again. I question whether it actually impacts the already noisy lives of city-dwelling folk. Either I’m not paying attention, or some people are super-sensitive.