First Flight cover franked with 1926 1p 50c blue (SG 217) tied by GUATEMALA CITY cds dated AGO 29 1926. Flown on the GUATEMALA CITY - SANTA ROSA inaugural flight with large CORREO AEREO GUATEMALA cachet in purple and three line 'Via primer correo aereo GUATEMALA STA-ROSA' cachet in red. SANTA ROSA arrival cds on front. A rare flight only 160 covers carried. (Muller #5, Goodman #AM6a)