Cover franked with 1929 15c on 15p black TRAIN issue with AIR opt, pair 2c bright blue, 3c deep purple and 1927 1c olive green TAX issue (SG 242, 229/230 & 223) all tied by boxed CORREO AEREO INTERNACIONAL 16 MAR GUATEMALA, C.A. cancels. Flown on the GUATEMALA - COSTA RICA first flight by PAA with boxed PRIMER ENVIO POSTAL AEREO DE GUATEMALA A CENTRO, SUD - AMERICA Y ANTILLAS 16 DE MARZO DE 1930 'Airplane' cachet on reverse. Costa Rican arrival marks of 17th & 18th March on front & reverse. A scarce flight, only 231 covers flown. (Muller #21, Goodman #AM22b).