EA M 4-0-4 postcard
My first airline collectible was a packet  picked from the seat-back pocket as a second grader aboard an Eastern Constellation trip to Miami. Among the contents were three postcards -- this one, a 1049-C Connie and a DC-7.    The packet  was called the Souvenir Flight Pack, and contained various other pieces of informational and promotional material. The year was 1956.