Upvote:2
Your Schengen visa counts from when you pass through immigration into the Schengen area. The airline will allow you to board as they understand the rules. And if by chance your country's immigration checks that you have the proper documents, they also allow departure for the same reason.
Likewise at the end of your stay, the date and time you pass out through German immigration determines your compliance with your visit limits, not the time your plane takes off.
As a side note, in countries such as the US where there are no exit formalities, the flight departure time & date counts as your official exit time.