(His flight is fully documented in his book “Persienflug”.) Some covers from this flight have postmarks of intermediate stops. 20 covers were flown Zűrich – Naples. 20 covers were flown Zűrich – Athens. 665 covers were flown Zűrich – Teheran. <Katalog fűr Schweizerische Flugpostsachen 1937> However “Flight” of 16 April 1925 gives a different number – “A number of air covers are now on the market bearing the inscription ‘Premier vol postal ZurichTeheran’ franked with Swiss air post stamps and showing the postmarks of both Zurich and Teheran. A total of 280 letters thus franked is said to have been carried by the pilot Mittelholzer on his interrupted flight, but their official status has yet to be determined. According to a Swiss journal, the general public was given no opportunity of transmitting correspondence by the flight in question.” “Aerophilately” (1980 London Congress) states that there were scheduled stops at Naples and Athens; and unscheduled stops at Smyrna (where Mittelholzer was delayed by the siege), Aleppo and Baghdad.
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