Gerrit Johannes "Geys"[1] Geysendorffer[a] (1 April 1892, Sliedrecht – 26 January 1947, Copenhagen Airport, Kastrup) was a Dutch aviation pioneer, knight in the Order of Orange-Nassau, and recipient of the 1926 Harmon National Trophy for the Netherlands.

[11] On 1 April 1920, Sergeant Geysendorffer and two of his fellow NCOs, Evert Jacob Need and Piet van de Griend, started a small air tourism business called N.G.G.

The Delftsche Courant wrote on 23 June 1920 that the plane, while flying over Venlo, caught on fire as a result of a burst fuel tank and subsequently came down,[13] while the Zutphensche Courant wrote that the plane made an abnormal swerve, came down, then caught fire as a result of a burst fuel tank right before impact.

[9] KLM Royal Dutch Airlines was founded on 7 October 1919, and its first scheduled commercial flight, between Croydon Airport and Amsterdam, took place on 17 May 1920.

[20] On 22 September 1925, a press conference was held including NVI director Wallaardt Sacré, KLM's Albert Plesman and the plane's designer Frits Koolhoven.

[21][22] On 22 January of the following year, Geysendorffer managed to reach Urk by plane to deliver post and yeast after the island had become isolated as a result of the freezing of the Zuiderzee, after a failed attempt two days prior.

[26] Geysendorffer was announced as recipient of the 1926 Harmon National Trophy for most outstanding aviator of the Netherlands in early 1927,[27] and the award ceremony took place in May.

[42] Van Lear Black's trip to Batavia and back was well-publicized,[35] and thousands of people came to Schiphol to witness the H-NADP's return to Amsterdam.

[37] At the official reception held upon the plane's arrival, Van Lear Black and the three crew members all were knighted in the Order of Orange-Nassau and received Silver Medals of the City of Amsterdam.

[40] Together with co-pilot Dirk Lucas Asjes and radio operator Pieter Pronk, Geysendorffer took part in the 1934 MacRobertson Air Race, flying the Pander S-4 with registration PH-OST,[6] formerly known as Postjager but renamed Panderjager for the occasion.

[6] Nevertheless, on 26 October, Geysendorffer sent a telegram that the crew had managed to repair the plane and held a successful 30-minute test flight; and that they would, with landing gear down, continue their voyage that evening as they "want[ed] to reach [their] goal in spite of severe setbacks" (Dutch: willen doel bereiken ondanks grooten tegenslag).

All crew and passengers on board died, including Swedish Prince Gustaf Adolf and U.S. opera singer Grace Moore.

[1] The crash was caused by loss of control on takeoff as a result of the tail fin's elevator gust lock pins not having been removed prior to the flight.