There might be transatlantic flights from Tegel, I'm not sure, but they're rare. Moscow and the Canary Islands are more or less the limits. I usually find myself going through Frankfurt, Paris or Amsterdam for intercontinental travel.
I was in Tegel a while ago, flying home to Dublin, so was in a non-Schengen section (Ireland's not in Schengen). The flight at the next gate was going to Beijing. I was kind of surprised, because Tegel has a very "small regional airport" feel (partially due to the weird design), but apparently there are flights to the other side of the world from there.
