Complex sentence: The damaged plane tried to return to Warsaw airport but a rapidly spreading in-flight fire caused a total failure of flight controls and a crash into the ground at 480 km/h in the forest 6 kilometers away from the Warsaw airport.
Split into simpler sentences: The damaged plane tried to return to Warsaw airport but a rapidly spreading in-flight fire caused a total failure of flight controls. The aircraft crashed into the ground at 480 km/h in the forest 6 kilometers away from the Warsaw airport.