 Complete the following phrase:  Many people, including drivers, crew members, officials and spectators, have been killed in crashes related to the sport of auto racing, in races, in qualifying, in practice or in private testing sessions. Deaths among racers and spectators were numerous in the early years of racing, but advances in safety technology, and specifications designed by sanctioning bodies to limit speeds, have reduced the rate of fatal accidents. Major accidents have often spurred increased safety measures and rules changes. Widely considered to be the worst accident is the 