The "Shipborne Containerised Air-defence System" ("SCADS") was a proposed modular kit to convert a RO-RO or container ship into aviation vessels, with one scheme allowing a container ship to be converted to a STOVL aircraft carrier in two days during an emergency and quick removal after use for storage. A prefabricated flight deck and ski jump would allow six Sea Harriers and two helicopters to be operated, with shipping containers providing hangarage for the aircraft and housing their support systems and personnel as well as defensive systems and missiles. Several variants of the SCADS concept were devised for different missions roles; one implementation was tailored towards helicopter operations for example. It was effectively a modern equivalent to the Second World War-era merchant aircraft carrier.