Thinking coalesced on a raid on Port Stanley Airport. Whether it was worth the effort was debated. Beetham initially proposed an attack in which a single Vulcan would drop seven bombs. This light bomb load would keep the refuelling requirements down to a minimum. However, tests conducted at the Garvie Island bombing range indicated that seven bombs would not be enough, but a full load of twenty-one would have a 90 per cent probability of putting one crater in the runway, with a 75 per cent chance of two craters. An attack was also expected to do damage to the dispersal areas and aircraft parked nearby. To minimise the danger from anti-aircraft guns and surface-to-air missiles, the raids would be carried out at night, preferably in bad weather. Damage to the surrounding area, possibly including parked aircraft, would make the raid worthwhile. While the Chiefs of Staff Committee were convinced that the operation was feasible and stood a good chance of success, the civilians at the Ministry of Defence were not so certain, and there were political implications to using the base at Ascension for offensive purposes, as Wideawake was technically a USAF base. The United States Department of State was consulted, and affirmed that it had no objection. Authority to proceed with the operation, codenamed Black Buck, was given by the War Cabinet on 27 April.