Ghost Flights - What Are the Legends?

There are stories of a kid like ghostly, ghostly children voices talking over the radio to where traffic controlled. There are stories of passengers who are not on a manifest just appearing and then saying something cryptic or heartwarming to someone on the crew for the restroom. Or they're, this is one of the most interesting ones in decades past stories of planes that disappear only to return hundreds of miles away from their destination.