I'm endlessly grateful for all responses to my questions and all the interesting stories that I read here!!! I know I didn't thank everyone personally but please know I AM grateful!!!
And another questions if you don't mind.
These days a pilot's experience is measured in flight hours. However, I saw quite a few 30-40's documentaries and news reels, especially from Germany and Soviet Union, where pilots' experience was measured in kilometers flown. Was that ever a thing in other countries? Maybe you happen to know when the transition to flight hours occurred?