Masta was lost to F1 racing after the 1970 season. Jackie Stewart's crusade to improve safety in racing was set in motion by his crash there in 1966, when his BRM ended upside-down in a ditch near a farmhouse on the outside of the corner, with fuel gushing out of the tank onto Stewart, who had broken ribs. At this point, many of the Formula One drivers disliked Spa (including Stewart and Jim Clark, who had some of his greatest wins there) because of the immense speeds that were constant on the track. While he was spectating at the 1972 12 Hours of Sebring, Stewart attempted to organise a boycott of the Spa 1000 km race that year, a move that was not respected by many of the drivers, because Spa was still popular with racing drivers outside of Formula One. Stewart later described the old Spa circuit in 1986 as being as "ferocious as a tiger", and he later described Masta in an interview in 2011 as perhaps the hardest corner on any racetrack he raced on in his career; even more so than Eau Rouge.