It is an attractive cover. From what I can see it is not a first flight cover but rather a first use of equipment on this route cover. The aircraft illustrated at the bottom of the front center is a Lockheed Super Constellation or affectionately called a "Connie". These were built by Lockheed and built between 1951 and 1959 and starting in 1952 they were used extensively by Trans World Airlines. Production stopped in 1959 because the new Boeing 707 jet airliner was introduced in 1958 and propeller aircraft were relegated to be used on shorter routes and by smaller airlines who could not afford the new jets.