The query "9 11 das geheimnis um flug ua 23" seems to refer to a German documentary titled "9/11 - Das Geheimnis um Flug UA 23" ("9/11 - The Secret of Flight UA 23"), which investigates the story of United Airlines Flight 23. This documentary explores the idea that besides the four planes used in the 9/11 attacks, another plane, UA 23, may also have been targeted or involved in related events. The documentary has about 42 minutes of duration, was released around 2023, and is available on RTL+ and some German TV streams. It covers the narrative that in the 9/11 attacks, four airplanes were converted into weapons of mass destruction, but possibly a fifth plane, UA 23, was also targeted. It includes never-before-heard interviews with the crew and explores hidden or lesser-known aspects related to this flight around the time of the September 11 attacks. If looking for more detailed historical context, United Airlines Flight 23 in 1933 was a different incident where a Boeing 247 crashed near Chesterton, Indiana, due to a bomb explosion onboard, marking one of the earliest proven cases of air sabotage in commercial aviation history. Let me know if the interest is in the 9/11 documentary "Das Geheimnis um Flug UA 23" or the historical Flight 23 sabotage incident, or both for further details.