Why is there class D around SeaTac's class B?

birdus

birdus

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Jay Williams
Why is there class D airspace around SeaTac's inner class B airspace? This seems uncommon to me.
 
birdus said:
Why is there class D airspace around SeaTac's inner class B airspace? This seems uncommon to me.
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Because there was probably some reason to keep the ‘core’ B surface area small. But maintaining ‘Surface Area’ beyond that to ensure folk ain’t flying around with 1 mile Visibility and Clear of Clouds not talking to any ATC, instead of 1000/500/3 and talking to ATC. Seattle isn’t the only one. Los Angeles is another.
 
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Yeah I was about to type “something to do with seaplanes” but you beat me to it...
 
I asked this question of a CFI years ago while planning a flight to KRNT for a X-country. He looked at me like I had a 3rd eyeball and said there was no such thing and then proceeded to quiz me on chart symbols and airspace. I never did get an answer...
 
Brad Z said:
I edited my post to include an image from foreflight. You’d see the same on the sectional chart legend.
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I see that. That’s in contradiction to the info in the margin of the Sectional where it lists SeaTac Tower as ‘continuous’ and the AF/D where KSEA is listed as CLASS D with no hours listed.
 
It is an Class D extension of the SEA Class B (sort of like a Class E extension of a Class D). I suppose it is was established to provide some degree of control over the airspace without the restrictions of a Class B. Nothing saying by NOTAM.
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There is a fairly large area southeast of BFI where the tower airspace of SEA. BFI, and RTN overlap. It is a practical impossibility to talk to three controllers at the same time. I attended the meetings when the dimensions of the original KSEA Class B airspace were being determined and I do not recall Class D entering into those discussions (it has been several decades). I'm sure that there is a Letter of Agreement between the three towers that explains it all in excruciating detail,but such LOAs are hard to find by Joe Sixpack. IMHO kkoran's post tells us all that we can know.

Bob
 
bobmrg said:
There is a fairly large area southeast of BFI where the tower airspace of SEA. BFI, and RTN overlap. It is a practical impossibility to talk to three controllers at the same time. I attended the meetings when the dimensions of the original KSEA Class B airspace were being determined and I do not recall Class D entering into those discussions (it has been several decades). I'm sure that there is a Letter of Agreement between the three towers that explains it all in excruciating detail,but such LOAs are hard to find by Joe Sixpack. IMHO kkoran's post tells us all that we can know.

Bob
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The Class D’s tell you who you need to be talking to. BFI’s is a really convoluted one. Does the normal circle thing from the West, clockwise to North and then takes a turn South and creates a wedge in between SEA’s and RNT’s. It goes as far South as the South end of SEA’s runways. Do you remember if Seattle’s original Class B had a Surface Area that followed the shoreline to the West like it does today?
 
luvflyin said:
The Class D’s tell you who you need to be talking to. BFI’s is a really convoluted one. Does the normal circle thing from the West, clockwise to North and then takes a turn South and creates a wedge in between SEA’s and RNT’s. It goes as far South as the South end of SEA’s runways. Do you remember if Seattle’s original Class B had a Surface Area that followed the shoreline to the West like it does today?
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Don't believe that it did. SEA was one of the early CBAs and they had a lot to learn. Before you accept this answer, consider that I am almost 92.

Bob
 
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