Which consulate should issue me a Schengen visa if I transit through several Schengen states?

Question

I am an Iranian citizen holding a U.S. permanent resident card (Green Card). My itinerary is as follows:
Los Angeles – Frankfurt – Vienna – Tehran

Apparently I need a visitor visa due to the fact that I have a "domestic" flight within the Schengen zone (Frankfurt–Vienna). Which consulate should I get my Schengen visa from: Germany or Austria?

Answer 1

Since there is apparently no “main destination” in your trip, your visa application should be processed by the first Schengen state you will enter, in your case Germany. This is from article 5 of the Schengen visa code (Regulation (EC) No 810/2009):

1. The Member State competent for examining and deciding on an application for a uniform visa shall be:

(a) the Member State whose territory constitutes the sole destination of the visit(s);

(b) if the visit includes more than one destination, the Member State whose territory constitutes the main destination of the visit(s) in terms of the length or purpose of stay; or

(c) if no main destination can be determined, the Member State whose external border the applicant intends to cross in order to enter the territory of the Member States.

[I highlighted the most important bit] The border between Germany and Austria is an “internal border”, which is why there will be no systematic passport check when landing in Vienna. Frankfurt is where you will cross the external border to enter the Schengen area (which is called “territory of the Member States” in the official regulation).