U.S. Scott 806 2 cent Prexie/Prexy picturing John Adams and Scott C39 6 cent air mail paying the 8 cent air mail rate. The cover was to be on a scheduled first FAM flight from New York City to Havana, Cuba but the flight was canceled because an agreement could not be reached with the Cuban government and the cover was returned to the sender. There is a marking on the reverse of the envelope saying "PHILATELIC SERVICE NOT RENDERED DUE TO CANCELLATION OF FLIGHT". There are two enclosures explaining the flight cancellation and return of the letter to the sender.
U.S. Scott 806 and C39 on Canceled 1951 First Flight to Havana, Cuba
Returns accepted for up to 30 days from the date of mailing, for any reason, as long as the item is returned in the same condition that it was sent.