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1. Why do we need a third runway?
The new runway is expected to help Sea-Tac Airport sharply reduce flight delays and give the airport the ability to operate efficiently in nearly all types of weather.
When there are low clouds, which occur about 44 percent of the time, Sea-Tac is permitted to use only one of its two existing runways for arrivals, because the runways are close together. The result is that all arriving air traffic is directed onto one runway, which slows things down and causes delays.
When incoming flights are delayed, airlines face added fuel and personnel costs. Travelers bear the cost of missed connections, including hotel stays, meals and incidental expenses while stranded. Those delays end up costing airlines and travelers millions of dollars each year.
A third runway will allow planes to land on two runways in all but the worst weather, reducing both delays and costs for passengers and airlines.
2. What kind of weather data justifies the need for the third runway?
Ten years of National Weather Service data, from both Boeing Field and Sea-Tac, was studied during the planning for the third runway. It showed that 44 percent of the time, Seattle has the kind of weather (clouds lower than 5,000 feet or visibility of five miles or less) that requires Sea-Tac to use one runway for arrivals.
3. If you need a third runway for poor weather arrivals, does that mean you won't use it during good weather?
In general, the third runway won't be needed as often in good weather. It will be needed mostly during peak periods. During good weather Sea-Tac can efficiently keep taxiing time to a minimum by using the other two runways, depending on the volume of planes and the discretion of pilots and air traffic controllers.
4. Will the third runway be used for takeoffs as well as landings?
The third runway will be most effective for arrivals, because of the extra time planes would take to taxi to the new runway for takeoffs. But the third runway could be used for departures for short periods when one of the other two runways is shut down for maintenance, or at the discretion of air traffic controllers and pilots.
5. If the only reason for a third runway is to provide a second all-weather runway, why not get rid of the existing second runway?
The existing second runway is closer to the airport terminal, so when weather allows, it will be preferable for both arrivals and departures in order to keep aircraft taxiing time to a minimum.
6. Why can't small aircraft use another airport?
In order to efficiently serve the current level of commuter passenger traffic, airlines fill their small planes flying to Sea-Tac with a mix of passengers destined for Seattle and those catching connecting flights. Airlines would not be economical or practical in splitting passengers between two airports.
7. Will there be a fourth runway?
There are no plans for a fourth runway at Sea-Tac Airport. The Puget Sound Regional Council (PSRC), our regional transportation planning organization, has recognized that it is not likely that Sea-Tac Airport will be able to indefinitely accommodate the region's long-term demand much beyond 2030. With this in mind, PSRC asked the state to undertake a comprehensive, long-range planning process for meeting long-range inter-regional and interstate passenger demands. We can also anticipate that advances in aviation technology may improve capacity at airports in the future.
8. How much will the third runway cost and when will it be finished?
The current projected budget $1.01 billion. The runway is set to open on Novermber 20, 2008.
See the Third Runway page for additional information.
