What is the farthest commercial flight on a B737-800 currently?
I believe this is GOL's Orlando->Brasilia flight at 3,778 miles. Prior to that it was Newburgh to Bergen at 3,456 miles. 

Lufthansa has a 737-700 but it is a Boeing Business jet equipped with extra fuel tanks and only 86 seats which makes a Frankfurt to Pune 4,158 mile flight. 

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