Originally Posted by
Kilianerz
My question is will the airline check in desk and TSA allow me through with just using my drivers license as identity or will they need to see a valid passport as well as it will be an international flight?
No valid passport, no deal. You can't even check into your flights.
Originally Posted by
Kilianerz
Also what will the German border patrol officer say when I show him my expired German passport? Will they let me through?
Although this is moot (as you can't make it back), German will let you in even with an expired passport, given the fact that in most countries, citizens have unrestricted rights to enter/exit the country.
The question is in what consequence if that happens.