FAA navigation map for the the Seattle area.
AIRPLANE TRAFFIC AND NOISE IN THE PUGET SOUND REGION
The continued growth of the Puget Sound region has led to the rise of Sea-Tac airport as a major player in global airplane travel. In 2017 Sea-Tac was the 9th busiest airport in the U.S. and the 31st busiest in the world with almost 47 million passengers served. The airport logged a total of 416,124 airplane arrivals and departures at its six runways, with about 96% of these being passenger flights. Of this passenger traffic, 89% is domestic and 11% is international, with 91 direct domestic routes and 28 direct international routes.
For this feature, we want to highlight interesting stats regarding airplane traffic, flight paths, airplane noise and flight elevation data for Sea-Tac airport. We analyzed data from the Port of Seattle: Aircraft Noise Monitoring System, Port of Seattle Public Disclosure site and the Washington Department of Ecology: Air Monitoring Stations.
Annual Flight Operations and Passenger Traffic
Let's begin with how the number of passengers and flight numbers have changed over the years. Over the 20-year period between 1997 and 2017 the number of passengers served by Sea-Tac has almost doubled. Interestingly, over this same time-frame, the total number of flight operations has fluctuated between around 310,000 to 440,000 flights: there were actually more flights in 2000 than 2017. This appears consistent with the industry: airline companies are packing more people onto planes, through a combination of reducing pitch (distance between a point on one seat to the same point on the seat ahead) and by increasing the number of rows. Further analysis is needed on how much of this increased capacity is being met by using larger airplanes.
For this feature, we want to highlight interesting stats regarding airplane traffic, flight paths, airplane noise and flight elevation data for Sea-Tac airport. We analyzed data from the Port of Seattle: Aircraft Noise Monitoring System, Port of Seattle Public Disclosure site and the Washington Department of Ecology: Air Monitoring Stations.
Annual Flight Operations and Passenger Traffic
Let's begin with how the number of passengers and flight numbers have changed over the years. Over the 20-year period between 1997 and 2017 the number of passengers served by Sea-Tac has almost doubled. Interestingly, over this same time-frame, the total number of flight operations has fluctuated between around 310,000 to 440,000 flights: there were actually more flights in 2000 than 2017. This appears consistent with the industry: airline companies are packing more people onto planes, through a combination of reducing pitch (distance between a point on one seat to the same point on the seat ahead) and by increasing the number of rows. Further analysis is needed on how much of this increased capacity is being met by using larger airplanes.
|
Airplane Models and Flight Types
In 2017, three airplane airliners made up 67% of all airplane traffic in and out of Sea-Tac:
|
A rendering of the Boeing 737 used by Alaska Airlines. In 2017 the airline had 48.5% of the market share for passenger travel at Sea-Tac and the Boeing 737 was the most commonly used airplane. (Rendering copyright www.norebbo.com)
|
The majority of airplane traffic in and out of Sea-Tac is passenger traffic, making up around 96% of total flights. Cargo is the second largest category with around 3%. What is all this cargo that is being flown out of Sea-Tac? In 2017, 28% of it were cherries, with a total of 24,537 metric tons leaving the State. General aviation, air taxi, test flight, charter, medical and other all make up a very small percentage of the remaining flight types.
Flight Paths
Sea-Tac has six runways, all are oriented in a north-south fashion. This orientation drives the flight paths that airplanes take for takeoff and landing as planes need to align themselves with the runway orientation. For safety reasons, planes take off or land into the predominant wind direction. Given the north-south orientation of the runways, it is difficult to significantly change flight paths. For a full discussion of flight patterns at Sea-Tac, see the Port of Seattle site.
Flight Paths
Sea-Tac has six runways, all are oriented in a north-south fashion. This orientation drives the flight paths that airplanes take for takeoff and landing as planes need to align themselves with the runway orientation. For safety reasons, planes take off or land into the predominant wind direction. Given the north-south orientation of the runways, it is difficult to significantly change flight paths. For a full discussion of flight patterns at Sea-Tac, see the Port of Seattle site.
Cruising over Beacon Hill at at an elevation of ~2,200 feet, a Boeing 787 plane makes its way to Sea-Tac airport
Noise Monitoring Stations and Arrival/Departure Data
The Port of Seattle operates 24 noise monitoring stations within the greater Sea-Tac airport area. Typically, if a flight produces a sound exposure level (SEL) of 72 decibels or more, then the flight gets logged by a noise monitoring station. We analyzed data for all 24 stations for 2017. Our first main finding shown below details the number of flights being picked up by each station, and whether they were arrivals or departures. Of the 416,124 flights that went in and out of Sea-Tac, there was quite a range in how many of them get logged by each station. SEA09, located at the top of Beacon Hill, picked up the most flights, with almost 50% of total flights logged. SEA04B, located in Magnolia, logged the least with less than 0.5% of total flights. As would be expected, parts of the region closer to the airport log more flights, but not all neighborhoods are affected equally: though West Seattle and Beacon Hill are a similar distance to Sea-Tac, the flight paths to Sea-Tac result in West Seattle noise monitoring station only logging <1% of total flights whereas Beacon Hill logs 50%. Note that (SEA-TAC) is not a noise monitoring station, but was added as a reference point, with an assumed 50% arrival/50% departure split.
The Port of Seattle operates 24 noise monitoring stations within the greater Sea-Tac airport area. Typically, if a flight produces a sound exposure level (SEL) of 72 decibels or more, then the flight gets logged by a noise monitoring station. We analyzed data for all 24 stations for 2017. Our first main finding shown below details the number of flights being picked up by each station, and whether they were arrivals or departures. Of the 416,124 flights that went in and out of Sea-Tac, there was quite a range in how many of them get logged by each station. SEA09, located at the top of Beacon Hill, picked up the most flights, with almost 50% of total flights logged. SEA04B, located in Magnolia, logged the least with less than 0.5% of total flights. As would be expected, parts of the region closer to the airport log more flights, but not all neighborhoods are affected equally: though West Seattle and Beacon Hill are a similar distance to Sea-Tac, the flight paths to Sea-Tac result in West Seattle noise monitoring station only logging <1% of total flights whereas Beacon Hill logs 50%. Note that (SEA-TAC) is not a noise monitoring station, but was added as a reference point, with an assumed 50% arrival/50% departure split.
Let's look at Beacon Hill (the station with the most airplane traffic logged) in more detail. On an annual basis, the flights logged by Beacon Hill are roughly split as 77% arrival and 23% departure. If we break the data down to a weekly level, we can see that the arrival/departure split changes throughout the year: there are proportionally significantly more departures logged over the summer months than in winter. This is consistent with wind patterns: in summer, winds typically come in from the north, so departures takeoff north into the wind.
Aircraft Noise
Noise from airplanes is complex. Clouds, wind, temperature, airplane type, altitude flown and whether it's an arrival or departure all affect the noise from a flight. The larger the airplane, the louder it is; planes are louder during takeoff than landing; new airplanes are typically quieter than older ones; when planes deploy their landing gear the noise level goes up. That said, we can can still summarize the noise from airplanes at each of the 24 noise monitoring stations by analyzing noise data. The LEQ Aircraft Noise (Equivalent Noise Level) metric averages aircraft noise over one day at each station. Plotted below are over 8,000 data points for 2017, with the overall average for all the stations. Select a noise monitoring station(s) to see daily LEQ values for it, and how noise at that station(s) compares to the overall average.
Noise from airplanes is complex. Clouds, wind, temperature, airplane type, altitude flown and whether it's an arrival or departure all affect the noise from a flight. The larger the airplane, the louder it is; planes are louder during takeoff than landing; new airplanes are typically quieter than older ones; when planes deploy their landing gear the noise level goes up. That said, we can can still summarize the noise from airplanes at each of the 24 noise monitoring stations by analyzing noise data. The LEQ Aircraft Noise (Equivalent Noise Level) metric averages aircraft noise over one day at each station. Plotted below are over 8,000 data points for 2017, with the overall average for all the stations. Select a noise monitoring station(s) to see daily LEQ values for it, and how noise at that station(s) compares to the overall average.
Noise Monitoring Station Decibel Readings
We logged sound volume readings from the Beacon Hill noise monitoring station to show the recorded instantaneous decibel readings in five second increments. The period spans a two-hour window, with recorded values typically fluctuating between 55 and 75 decibels. During this time frame, sixty planes were logged by the noise monitoring station.
We logged sound volume readings from the Beacon Hill noise monitoring station to show the recorded instantaneous decibel readings in five second increments. The period spans a two-hour window, with recorded values typically fluctuating between 55 and 75 decibels. During this time frame, sixty planes were logged by the noise monitoring station.
Flight Altitude
We looked at the altitude that airplanes are flying at. The interactive graph below shows a 30-mile long profile starting in North Seattle and extending to Des Moines that encompasses 19 noise monitoring stations (5 of the noise monitoring stations are not shown to improve readability of the graph). Select any individual day in September of 2018 to see the elevation of flights for that day, whether they were arrivals or departures, elevation of flight, flight type, and the runway it landed it. Notice how airplanes are typically flying at a lower elevation when arriving than departing: arriving aircraft tend to approach at a fixed angle of 3-degrees, while the angle for departing aircraft varies typically between 5 and 10-degrees and is driven by aircraft type, weight, air temperature and wind speed. For the month of September at Beacon Hill (SEA09), this translates to an average arrival altitude of 2,400 feet and an average departure altitude of 4,400 feet.
We looked at the altitude that airplanes are flying at. The interactive graph below shows a 30-mile long profile starting in North Seattle and extending to Des Moines that encompasses 19 noise monitoring stations (5 of the noise monitoring stations are not shown to improve readability of the graph). Select any individual day in September of 2018 to see the elevation of flights for that day, whether they were arrivals or departures, elevation of flight, flight type, and the runway it landed it. Notice how airplanes are typically flying at a lower elevation when arriving than departing: arriving aircraft tend to approach at a fixed angle of 3-degrees, while the angle for departing aircraft varies typically between 5 and 10-degrees and is driven by aircraft type, weight, air temperature and wind speed. For the month of September at Beacon Hill (SEA09), this translates to an average arrival altitude of 2,400 feet and an average departure altitude of 4,400 feet.
References/Notes:
1) Port of Seattle: Aircraft Noise Monitoring System.
2) Port of Seattle Public Disclosure site.
3) Washington Department of Ecology: Air Monitoring Stations.
4) SEA-TAC International Airport Economic Impacts. Port of Seattle. January 2018.
1) Port of Seattle: Aircraft Noise Monitoring System.
2) Port of Seattle Public Disclosure site.
3) Washington Department of Ecology: Air Monitoring Stations.
4) SEA-TAC International Airport Economic Impacts. Port of Seattle. January 2018.