Seattle Tacoma International Airport (SEA) doesn't allow Uber X to pickup in the airport, so you can't call an Uber X from airport. Last time I figured out a way to hack it by walk to the light rail station, I did the same today and then the driver told me an even better solution!
It's simple, just drop you location of requests to the place where UberX available when you are in the airport. In the below example I just use the same place near the light rail station you can walk.
Once you get a driver, immediately contact the driver and let them know you are actually request a terminal pickup. Isn't it simple?
In my case, the driver instantly called me to ask me if I need a pickup in terminal, he told me many uber x drivers already use this trick and they actually prefer to pick from the terminal instead of that light rail station!
Wish SEA will eventually open up the restriction, since they allow taxi or friends/family cars pickup why not allow uber?