Despite the improvements, the circuit became unsafe for the increasingly faster and stiffer ground effect cars of the late 1970s, and a few horrendous, sometimes fatal accidents occurred (such as those that claimed the lives of Helmut Koinigg and François Cevert). Increasingly rowdy segments of the crowd began to tarnish its image as well. Finally, in May, 1981, several months after Alan Jones had won the 1980 race for Williams, the International Auto Sports Federation removed the race from its schedule because the track had failed to pay its $800,000 debt to the teams.