Blue sky sessions are the sessions where new ideas are formed, molded and cultivated. This is the one thing everyone wants to do. Think of it this way, you have a room of imagineers and one of the heads say, Walt Disney World wants a new e-ticket attractions....any ideas? Then the room is just flooded with ideas, sketches, story ideas, everything. It's the beginning of all attractions. Blue Sky is named so because "skies the limit" anything goes if you will. There are no bad ideas at this phase.
Blue sky sessions are lead in many different ways and many different heads of various departments attend said meetings. Sometimes guidelines have already been put into place i.e. Tokyo Disney Seas is wanting their own version of Tower of Terror. The Imagineers start at that point and everyone collaborates to come up with what we see today (a new storyline and look of the classic attraction). Once each piece of the attraction puzzle is on the same page they break....show writers begin working on show dialogue and soundtrack ideas, storyboard artists and illustrators begin developing the different scenes of the ride, engineers and research & development being brainstorming new and exciting technology to support the ride. Once most of the different pieces are done, they have to present their idea in a neatly designed package to the heads of the different parks. This is commonly known as a "dog and pony" show and or the elevator pitch. If the idea gets the green light then it's numbers time, all good attractions come with a price tag. Once price is finalized, which in some cases attractions have to be scaled back, etc.
Certain Imagineers and their teams are called upon when certain blue sky sessions are formed. You can imagine when a big scale, E attraction is on the plate you're going to be looking at Tony Baxter to lead it/head it up. If it's a major revamp of a classic attraction and or upgrades Kathy Rogers and Eric Jacobson might be leading that. If it's an entire redo of DCA all the different divisions may have a part in it. It all depends on the scope of the project.
I hope that helps.
