I recently flew internationally (Miami to Amsterdam and back) and did a lot of knitting in flight research. Craftster (www.craftster.org) has a very good (but long) thread that I think is worth reading.
The search function there is down right now or I'd post a link but you may want to try it later.
There are certain countries such as the UK and especially Australia which are not knit-on-flight friendly I have read. The Netherlands did not give my any trouble with it.
I have heard of needles and yarn being confiscated somewhat randomly so I wouldn't take your favorite stuff otherwise bring a pouch that you can use to mail them to yourself if the airport security is planning on taking your stuff away.
I used the Clover pendant (linked to above) and brought my Denise needles and had no problem. Metal needles, any type of scissors, sharp darning needles, long corded circular needles are the highest risk to fly with.
Good luck - let us know how Germany treats on flight knitters and I hope you have an awesome trip!