This striking Philippine Islands airmail-related issue features a bold “MANILA–MADRID / ARNACAL FLIGHT – 1936” blue overprint applied to the 4 centavos carmine stamp from the U.S. Administration period. Issued for the special experimental ARNACAL trans-Pacific/Asia–Europe flight, it represents an important early aviation link between the Philippines and Spain. The surcharge reduces the face value to 2 centavos, clearly indicated by the large blue numerals. A desirable specialty item for collectors of Philippine airmail, pioneer flights, and overprinted varieties, often sought for its strong historical connection to pre-WWII international aviation efforts.