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Flight Patterns 

Aircraft primarily depart heading into the wind. So whether an airplane departs to the north (north flow) or the south (south flow) depends on wind conditions. During clear weather in the Puget Sound region, winds tend to flow out of the north necessitating departures to the north. Cloudy or overcast days mean winds tend to flow out of the south necessitating departures to the south. Given our northwest climate, Sea-Tac Airport operates in south flow about 65% of the year.

north flow

South Flow

Both maps represent a typical 24-hour period of jet traffic at Sea-Tac Airport.


View local area flight tracking and noise information

Aircraft WebTrak enables the public to independently investigate flights on the web. Click the image to view flights and aircraft information. 
Download instructions for WebTrak (PDF).

Effects of Weather on Noise

Many atmospheric phenomena can vary the intensity of aircraft noise from day to day at a given location. Noise propagation, or the transmission of sound waves through the air, can be influenced by wind, temperature, cloud cover and fog. These conditions do not describe all weather phenomena and their effects on noise, but may help explain the day-to-day variations in the propagation of aircraft noise.