The Operation Black Buck raids were staged from RAF Ascension Island, close to the Equator. The Vulcan was designed for medium-range missions in Europe and lacked the range to fly to the Falklands without refuelling several times. The RAF's tanker planes were mostly converted Handley Page Victor bombers with similar range, so they too had to be refuelled in the air. A total of eleven tankers were required for two Vulcans (one primary and one reserve), a daunting logistical effort as all aircraft had to use the same runway. The Vulcans carried either twenty-one bombs internally or two or four Shrike anti-radar missiles externally. Of the five Black Buck raids flown to completion, three were against Stanley Airfield's runway and operational facilities, while the other two were anti-radar missions using Shrike missiles against a Westinghouse AN/TPS-43 long-range 3D radar in the Port Stanley area. Shrikes hit two of the less valuable and rapidly replaced secondary fire control radars, causing some casualties among the Argentine crews. One Vulcan was nearly lost when a fuel shortage forced it to land in Brazil.