Day
'Day' means the time from half an hour before sunrise until half an hour after sunset (both times exclusive), sunset and sunrise being determined at surface level;
I got this from the air navigation order 2000. The times of Sun set and rise can be calculated of surfed in the net or look up on the Jeppessen manual.
It is also clearly writen on the uk aip gen 2.7.
Many thanks to all.
DOES THIS DEFINITION APPLY FOR THE REST OF EUROPE AND THE USA?