what aircraft first flew before 1969-09-13 and is the same type as blackburn skua?
(AND aviation.aircraft (AND (JOIN (R aviation.aircraft_model.aircraft) (JOIN aviation.aircraft_model.aircraft_type (JOIN aviation.aircraft_type.aircraft_of_this_type m.02sfks))) (le aviation.aircraft.first_flight 1969-09-13^^http://www.w3.org/2001/XMLSchema#date)))