After the deaths of drivers Ayrton Senna and Roland Ratzenberger at the 1994 San Marino Grand Prix, worldwide media attention focused on the charismatic triple-world champion Senna, rather than Ratzenberger, a virtual unknown driving for the minor Simtek team. Mosley did not go to Senna's funeral, but attended that of Ratzenberger. In a press conference 10 years later Mosley said, "I went to his funeral because everyone went to Senna's. I thought it was important that somebody went to his." In the aftermath of the deaths, and a number of other serious accidents, Mosley announced the formation of the Advisory Expert Group chaired by Professor Sid Watkins, to research and improve safety in motor racing. Watkins, who learned of his new role by hearing Mosley announce it on the radio, has called it a "novel and revolutionary approach". The resulting changes included reducing the capacity and power of engines, the use of grooved tyres to reduce cornering speeds, the introduction of the HANS device to protect drivers' necks in accidents, circuit re-design, and greatly increased requirements for crash testing of chassis.