Please be informed about the special radio mandatory zone and the restricted areas around Frankfurt city, which will be active on the next weekend from 02. until 04. of October!
Check DFS-AIS for more information: DFS-AIS – Flugbeschränkungsgebiet Tag der Deutschen Einheit
see also https://www.pilotundflugzeug.de/artikel/2015-09-28/Flugbeschrankung_Frankfurt
for further info about some confusion on the topic. All in german 😉