Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: IB+ Gold, TK E+, Hyatt Globalist, Marriott LTP, IHG Diamond
Posts: 14,170
FRA-MAD will be operated by Iberia.
I cannot think of a single decent reason to book that route via Vueling instead of via Iberia.
And FWIW, if you were booking Iberia flights for elite status / miles / etc. reasons I could understand it... but otherwise just book a Lufthansa direct flight!
P.S. Vueling do not operate a direct Barcelona to / from Frankfurt flight for reasons I donīt quite understand... But that doesnīt mean you should be searching the Vueling website for a route they donīt operate.