They are also (for those that don't know) the primary airport surrounded by Bravo airspace. Why do they have both?
History..it had D (or the D equivalent) long ago, pre bravo, and they just kinda kept it. But why?
Proximity..very close to 2 other converging class D airports (BFI and RNT). But wouldn't the B still take care of that?
Because it has a tower..and as a general rule, if you have a tower, you have D. I have been too lazy to get my other sectionals to see if other major airports in B airspace also have D, but I don't remember seeing any. I am sure there are others.
Any help in answering this would be wonderful. It has been bugging me for years.
[Edited 2005-06-16 04:15:36]