In aerophilately, a branch of philately, a first flight cover, also known by the acronym FFC, is mail that has been carried on an inaugural flight of an airline, route, or aircraft,[1] normally postmarked with the date of the flight[2] often of the arrival destination proving it was actually carried on the aircraft[3] and may have a special flight cachet[4]: 184 and/or an arrival postmark. Because many first flight covers are essentially made as collectables they can be considered philatelic mail though others consider them to be postal history.[5]
hornung
was invoked but never defined (see the help page).