Complex sentence: It was built in World War II to permit heavily-fuelled aircraft to take off on transatlantic flights and is certificated to accept the Space Shuttle should it need to make landfall in Europe, and provides for the Boeing 747 Shuttle Carrier Aircraft to get airborne again.
Split into simpler sentences: It was built in World War II to permit heavily-fuelled aircraft to take off on transatlantic flights. It is certificated to accept the Space Shuttle should it need to make landfall in Europe, and provides for the Boeing 747 Shuttle Carrier Aircraft to get airborne again.