Is Singapore air doing USA-Germany?????????????
Anyway, many ways to get to Germany. If you are heading for Hannover from the USA, there are many ways, and some fun ones too, of course depending on your time.
You can go over Britain or Iceland, (and also in that case even France, or Denmark) and then hop onwards with the low-price companies. Or you can take it straight.
Hannover has an airport, Hamburg is not that far away either.
Go looking and post, will be of as much help as my time allows.