I just quit being an airline pilot to purse my dreams of being a nurse. Anyway, my crew and I were walking down a jet bridge to the airplane, and we walked past a family that had just gotten off the plane. The mother was putting a baby in a stroller, the father was standing behind her, and their young son (about 6 years old) was standing right behind the father, doing a little dance. As we start to walk by this family, the son jumped across the jet bridge right in front of me and the other pilot. Then, in an instant, the son disappeared. I stopped dead in my tracks, and watched the family as the mother finished strapping the baby in, and the walked up the jet bridge to the terminal. I looked carefully, but there was absolutely no boy with them. I looked around inside of the airplane to see if the boy was in there, but he wasn't. I asked the other pilot if he had seen the boy, but he hadn't. I was the only one who saw him, but he was plain as day to me. I could tell exactly what he looked like, what he was wearing, and in an instant, he was gone. I truly believe that this was a son that had passed away, but continued to hang out with the family. This happened to me about 2 years ago.