These airmail stamps were issued in 1924 by the Colombian/German Airline SCADTA (Sociedad Colombo-Alemana de Transportes Aeros) for the payment of airmail postage from the Colombian port of Barranquilla into the interior (e.g. Bogotá). They were overprinted “S” for prepayment in Switzerland of the Colombian airmail fee on letters destined for the Colombian interior. They were distributed within Switzerland by the Colombian Embassy in Bern and were to be placed on letters in addition to the regular Swiss postage necessary for international surface mail.
Red “R” overprint for payment of SCADTA registered mail fee