Due to the weather, the flight couldn’t proceed from Karibib as scheduled on 19 May 1914. Instead, local exhibition flights were conducted on 20-21 May 1914. On 22 May 1914, the airmail flights resumed with the flight from Karibib to Okahandja. Because of the delay, mail for this leg typically carries one of two cancel dates - 19 May 1914 (mail accepted for the originally scheduled flight) or 21 May 1914 (mail accepted during the delay). The mail accepted in Karibib bears a 3-line cachet - “Erste FLUGPOST / Swakopmund Karibib Windhuk / Deutschsüdwestafrika” (First airmail / Swakopmund Karibib Windhuk / German Southwest Africa), Friedemann FN3. The cachet is typically in green ink for the 19 May 1914 mail, and in black-violet ink for the 21 May 1914 mail.
See GermanStamps.net example above for FN3.
On 24 May 1914, Buchner left Okahandja for Windhoek, but he had to make emergency landings in Teufelsbach and Brakwater due to bad weather en route. He finally landed on the Windhoek racecourse on 27 May 1914. Mail carried from Okahandja received a 3-line violet cachet - “Erste FLUGPOST / Deutsch Südwestafrika / Okahandja Windhuk” (First airmail / German Southwest Africa / Okahandja Windhoek), Friedemann FN4.