How Sea-Tac Airport preps for winter

Story No. 4 in a series
   Just as you winterize your home, Northwest landmarks get prepped for winter, too.
   That includes Seattle-Tacoma International Airport, ranked No. 15 in the U.S. for number of passengers carried.
   Sea-Tac began civilian flights in 1946 and opened a modern terminal in 1949. Concourses were added over the years (shown here in 1961) as jet travel boomed until, in 1973, major expansion and upgrades quadrupled the terminal’s size.
   The airport uses three alert levels to classify winter weather – snow watch, when National Weather Service forecasts call for snow below 1,000 feet; modified snow alert, when forecasts predict 3 inches of snow or less; and snow alert, once it’s clear that accumulations will reach more than 3 inches, or when freezing rain is imminent.
   The Port of Seattle oversees Sea-Tac, which is responsible for clearing snow and ice from its own runways, taxiways, and loading areas, as well as parking areas and roads.
   You might wonder, who de-ices the planes? That responsibility falls on the airlines themselves, not the airport, as shown in this photo of a United jet.
   Sea-Tac uses biodegradable liquid anti-icer on its runways and goes through 36,000 gallons in an average year. Workers apply it at 33-34 degrees. When temperatures plummet far below freezing, solid sodium acetate also is applied.
   The fleet and equipment used to clear snow includes:

  • 4 plow and broom trucks
  • 7 high-speed snowplows
  • 5 snow blowers
  • 10 high-speed brooms
  • 3 sander/plows
  • 4 de-icing trucks
  • …plus 350 tons of runway sand.

   And here’s something a little unique: Sea-Tac has two friction-testers – cars (Saabs, specifically) used to measure stopping distance on runways. A driver steers the car down the runway and lowers a computer-monitored tire, which measures how slick the tarmac is.
   Sea-Tac Airport sits at 433 feet above sea level, and in an average year it gets 12 inches of snowfall. The winter of 2008-2009 was more severe, with 23 inches falling, requiring crews to spread 120,000 gallons of anti-icing fluid!
   Which made me wonder, how often does Sea-Tac shut down flights entirely because of snow or ice?
   “Very, very rarely. In fact, almost never,” said Perry Cooper, Sea-Tac’s manager of public affairs. “It happened last in the big snow of 2008 due to unexpected ice fall. The runways were closed in the morning for a short time until crews could get out de-icer for the runway.”
   And out of curiosity, how long is Sea-Tac’s longest runway? 1 mile? 1.5 miles? 2 miles?
   Answer: its longest runway is 11,901 feet, or 2.25 miles. That’s a lot of surface to plow.

by  Jon Osterberg

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