Bidspirit auction | Worldwide Pioneer Flights - Switzerland

Worldwide Pioneer Flights - Switzerland - 1930 (December 2), registered cover delivered by Ad Astra Aero Africa Pioneer Flight on leg Zurich - Cartagena - Alicante, franked by three stamps, blue confirmation cachet, undelivered and returned to Fribourg on December 11, appropriate markings on front and reverse, F/VF, Est. $150-$200, Sc. #C9, C12