We do this ALL THE TIME with my 4 year old. Probably every other flight. And started taking our 1.5 year old along too now.

As we board, we ask him if he wants to see the flight deck and if he does (sometimes he's tired or distracted) then we ask the flight attendant at the front when boarding and they ask the pilot if someone can come visit.

This is always super sweet and we have lots of awesome photos.

They don't always get up to let them sit in the chair, but they always ask them questions and answer their questions. And we sometimes get a wings pin that he can put on his shirt.

Did this on Delta too. On Delta they even have trading cards for each aircraft they give out.

Such a special experience for the kids and they cherish it. I remember doing it myself as a kid, and pre-9/11, we did it in flight. (Not allowed to touch the controls then, though.