Hi!
I'm new and try to open the tutorials located on the project's homepage
https://www.flightgear.org/flying/ > New Pilots > Looking for documentation > Official FlightGear Manual
All links to all pdf's in all languages return a "Whoops, we can't find that page." 404 page.
This seems to be the best way to report this issue.
Looking forward to someone fixing this!
--Cagy
GL&HF