Switzerland 1926 (November 26), Pioneer Africa Flight registered cover from Zurich to Egypt, franked by four stamps, black boxed confirmation marking, Alexandria "3.Dec.26" arrival ds is alongside, undelivered andreturned to Switzerland on December 21, appropriate hs on reverse, mostly VF, Est. $250-$300

150.00

1929 (December 15), Pioneer Ad Astra Aero Pioneer Flight to Khartoum, stationery postcard 20c red, uprated by three stamps, including the Mythen 3fr red, boxed confirmation cachet and arrival ds is alongside, mostly VF, Est. $100-$150

75.00

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 onDecember 11, appropriate markings on front and reverse, F/VF, Est. $150-$200

100.00