to book out where we were going to fly, to comply with "SAR Watch".
Yes, isn't that the exact same reason for which we are supposed to file a flight plan?
we keep a 'C' book for pilots to log their flights after arrival.
and before taking off, too, I should expect? That is what we do here in BE, it is in fact a legal obligation; though it is not in France,
AFAIK. In Germany, the "Flugleiter" (= mandatory radio operator at any aerodrome) will do it for us. Both the arrival and the departure, I mean, in all countries I know about.