An exceptional piece of early transatlantic aviation history associated with German aviator Captain Wolfgang von Gronau’s pioneering 1931 flight in the Dornier Wal flying boat “Grönland\-Wal” (Greenland Whale), which crossed the North Atlantic via Iceland, Greenland and Canada before reaching the United States\. Historical Background In August–September 1931, von Gronau completed his second successful transatlantic expedition, demonstrating the feasibility of a regular northern air route between Europe and North America\. The expedition marked an important milestone in long\-distance aviation and the development of future transatlantic air services\. The Postal Item Original 1931 airmail cover associated with this historic expedition and regarded as genuinely flown mail connected with von Gronau’s second Atlantic crossing\. The cover features contemporary postal markings and is accompanied by a handwritten French collector’s note describing the crossing, the Dornier Wal, the route via Greenland, and the welcome given to von Gronau and his companions in America\. The note also refers to St\. Paul, 25 May 1931, and to a welcome message connected with the arrival of Captain von Gronau and his crew, providing additional provenance and historical collecting context\. The Four Pioneering Aviators The expedition involved Captain Wolfgang von Gronau and three fellow aviators: - Wolfgang von Gronau – Expedition commander and pilot\. - Franz Hack – Mechanic\. - Fritz Albrecht – Radio operator\. - Ghert von Roth – Co\-pilot on the 1931 expedition\. The crew’s signatures add considerable historical and aerophilatelic interest, linking the cover directly with the pioneers of northern transatlantic aviation\. International Auction Reference A comparable group of Wolfgang von Gronau material was offered by the British philatelic auction house **Argyll Etkin Ltd\., Auction No\. 57, Lot 576, on 6 November 2025**\. The group comprised: - A September 1931 cover bearing a Montreal flight cachet, described as apparently flown on the final leg of the second transatlantic flight\. - A commemorative welcome cover referring to von Gronau and his three companions as twice conquerors of the Atlantic by air\. - A photograph of the aircraft\. All three items were described as bearing the signatures of the four crew members. This reference is provided for historical and philatelic comparison only and does not represent a valuation of the present individual item\. Auction reference: Argyll Etkin Ltd\. – Auction 57 – Lot 576 – 6 November 2025\. Collecting Significance An appealing and historically important item for collectors of: - Pioneer aviation and early airmail. - Transatlantic flight covers - Wolfgang von Gronau and Dornier Wal aircraft - Greenland and Arctic aviation - Signed aviation memorabilia - German and North American aerophilately. A fascinating witness to the pioneering era when the northern Atlantic air route was still being explored by courageous crews flying . An attractive opportunity to acquire a significant piece of early transatlantic aviation and aerophilatelic history\. I can combine the shippings strictly following the Catawiki rules . IMPORTANT INFO: Following a recent change in international sector regulations, specifically Articles 18 and 19 of the Universal Postal Convention, starting from January 1, 2026, it will no longer be possible to send items (goods with or without commercial value) using International Registered and International Insured services, which will continue to be used exclusively for sending documents. It means that starting from January 1st, 2026, I will ship abroad only by "POSTE DELIVERY INTERNATIONAL