While the Vulcans were capable of carrying conventional munitions, this had not been done for a long time. To carry twenty-one bombs, the Vulcan required three sets of bomb carriers, each of which held seven bombs. Their release was controlled by a panel at the navigator's station, known as a "90-way", that monitored the electrical connections to each bomb, and was said to provide 90 different sequences for releasing the 1,000-pound bombs. None of the Vulcans at Waddington were fitted with the bomb racks or the 90-way. A search of the supply dumps at Waddington and RAF Scampton located the 90-way panels, which were fitted and tested, but finding enough septuple bomb carriers proved harder, and at least nine were required. Someone remembered that some had been sold to a scrapyard in Newark-on-Trent, and they were retrieved from there. Locating sufficient bombs also proved difficult, and only 167 could be located. Some had cast bomb cases rather than machined ones, which was problematic as they tended to shatter, and this mission required bombs that would penetrate into the ground. Training of crews in conventional bombing and in-flight refuelling was carried out from 14 to 17 April, when Military Air Traffic Controllers from the Military Area Service (M.A.S.) suit at London Terminal Control Centre in West Drayton, Middlesex, took the Vulcan bombers and Victor tankers 250 miles off Land's End in the Atlantic Ocean, where the vast majority of their aerial refuelling training was completed, always at night.