On 1st May 1994 3 times F1 World Champion Ayrton Senna was killed at the San Marino Grand Prix.

This video shows the likely cause of the accident.

The car bottomed out on the way down to the  Tamburello corner. This meant that the tyres were not in contact with the road and the car was instead resting on the metal skids on the underside for just a split second.

The car immediately loses downforce in this situation, denying Senna the grip he needs to round the corner. The rear of the car steps out.

A split second later, Senna instinctively tries to correct the backend with the streering and stands hard on the brakes. The car begins to slow down but in the end Senna runs out of road.

A tragic end to an incredible driver's life.