Even at the start of the race, Pedro Lamy and JJ Lehto were involved in an accident. Track officials deployed the Opel Vectra safety car, driven by Max Angelelli at the time, to slow down the field and allow the debris from the accident to be removed. The cars proceeded under the safety car for five laps. Before the sixth lap, David Brown told Senna via pit-to-car radio that the safety car was pulling off, and Senna acknowledged the message.
On lap 7, the second lap at racing speed, Senna’s car left the racing line at the 190 mph Tamburello corner, ran in a straight line off the track and struck an unprotected concrete barrier. Telemetry shows he left the track at 310 km/h (190 mph) and was able to slow the car down by braking to 218 km/h (135 mph) in slightly under 2 seconds before hitting the wall.
The car hit the wall at a shallow angle, tearing off the right front wheel and nose cone, and spun to a halt. After Senna’s car came to a halt, he was initially motionless in the cockpit. After about ten seconds, from the close-up aerial footage, his head is seen to move about one inch to the left before returning to where it was. Then, he never moved again.
What appeared to have happened was that the right front wheel shot up upon impact and entered the cockpit, striking the right frontal area of his helmet. The violence of the wheel’s impact pushed his head back against the headrest, causing fatal skull fractures. A piece of suspension attached to the wheel had partially penetrated his Bell M3 helmet and caused trauma to his head. In addition, it appeared that a jagged piece of the upright assembly had penetrated the helmet visor just above his right eye.
Senna was using a medium sized (58 cm) M3 helmet with a new “thin” Bell visor. Any one of the three injuries would probably have killed him.
After the crash it was immediately evident that Senna had suffered some form of injury, because his helmet was seen to be motionless and leaning slightly to the right. The subtle movement of his head in the seconds that followed raised false hopes.
Moments after the crash, Angelo Orsi, a photographer and a friend of Senna, took photographs of Senna in the car after his helmet was removed and Senna being treated before marshals blocked his view. Despite receiving numerous offers, the photographs have only been seen by Orsi and the Senna family who insisted that Orsi not publish the photographs.
Fire marshals arrived at the car and were unable to touch Senna before qualified medical personnel arrived. Senna was pulled out of the car minutes after the accident. Television coverage from an overhead helicopter was seen around the world, as rescue workers gave Senna medical attention. Close inspection of the area in which the medical staff treated Senna revealed a considerable amount of blood on the ground.
From visible injuries to Senna’s head it was evident to attending medical professionals that he had sustained a grave head trauma. An emergency tracheotomy was conducted trackside to establish a secure airway through which the medical personnel could artificially maintain his breathing. The race was stopped one minute and nine seconds after Senna’s crash.
Williams team manager Ian Harrison went up to race control, finding a scene where many race officials were sensing that Senna’s crash had been serious. Bernie Ecclestone later arrived in race control to calm the situation.
Professor Sid Watkins, a world-renowned neurosurgeon, Formula One Safety Delegate and Medical Delegate, and the head of the Formula One on-track medical team, performed the on-site tracheotomy on Senna.
Watkins later reported:
Watkins cleared the respiratory passages, stemmed the blood flow, replaced blood lost from the accident and immobilised the cervical area. Watkins radioed for a medical helicopter and asked the intensive care anaesthetist, Giovanni Gordini, to escort Senna to Maggiore Hospital. Approximately 10 minutes after Senna’s crash, a miscommunication in the pits caused a Larrousse car piloted by Érik Comas to leave the pit lane and attempt to rejoin the now red flagged Grand Prix.
That incident with Comas was spotted by Eurosport commentator John Watson as the “most ridiculous thing I’ve ever seen at any time in my life”. Frantic waving by the marshals at Senna’s crash site prevented the Larrousse from risking a collision with the medical helicopter that had landed on the track.
Senna’s car returned to the pitlane where officials impounded it. However, an unidentified person from Williams insisted that the black-box data carried on the car should be removed. At 3:00pm, the helicopter landed in front of the Maggiore Hospital. Doctors rushed Senna into intensive care; a brain scan confirmed the diagnosis made on the track. At 3:10pm, Senna’s heart stopped beating, doctors restarted his heart, and he was placed on a life-support machine.
Senna’s brother Leonardo arranged for a priest to perform the last rites which occurred at 6:15pm. Senna’s heart stopped beating at 6:37pm, and it was decided not to restart it. Senna was pronounced dead at 6:40pm with the official time of death at 2:17pm.
It was later revealed that, as medical staff examined Senna, a furled Austrian flag was found in his car—a flag that he had intended to raise in honour of Ratzenberger after the race.
Sometime after the race, Ian Harrison was called by an Italian lawyer informing Harrison of Senna’s death and that it was being treated as a “road traffic accident”. Early in the morning of 2 May, Harrison was called by another lawyer who took him to a mortuary. Harrison decided not to see Senna’s body upon being asked.