For a six year old I would sugest the sim which everyone with any interest will enjoy, however I think he is a little young to fly a plane cold turkey. Most kids his age seem to think crashes are the exciting part. While he is learning the sim I think an elec offroad car or truck will provide lots of entertainment with less risk. From there a nitro car or truck to teach engine management then if the interest is still there he is ready for the plane. He will probably learn the sticks much faster than most of us, but there are other things to learn in this hobby that are not inherant in a 6 year old. Good luck and you are to be comended for the effort. He is a lucky kid inspite of his dad being gone for a while