Black & white PPC 'Buenos Aires - Plaza Hotel' franked on message side with1929 2c green and 1c deep blue (SG 457 & 466) tied by GUAYAQUIL cds dated 12-3 1930 with boxed 'POR AVION BY AIR MAIL' marking alongside. Flown on the Guayaquil - Georgetown, British Guiana flight by NYRBA with fine strike of three line '1ST AIR MAIL SERVICE ECUADOR - BRITISH GUIANA PANAMERICAN - NYRBA LINE' first flight cachet in black on front. AIR MAIL BRITISH GUIANA arrival cds on reverse. A very scarce flight. (Muller #36)