Death of Ayrton Senna

Death of Ayrton Senna

Ayrton Senna on board his damaged Williams FW16 after his crash on lap 7 of the 1994 San Marino Grand Prix Senna's fatal accident just after the moment of impact at the Tamburello corner of the Imola circuit
Date	1 May 1994
Location	Imola, Emilia-Romagna, Italy

Three-time Formula One World Champion Ayrton Senna died on May 1, 1994, as a result of his car crashing into a concrete barrier while he was leading the 1994 San Marino Grand Prix at the Autodromo Enzo e Dino Ferrari in Italy. The previous day, Roland Ratzenberger had died when his car crashed during qualification for the race. His and Senna's accidents were the worst of several accidents that took place that weekend and were the first fatal accidents to occur during a Formula One race meeting in twelve years. They became a turning point in the safety of Formula One, prompting the implementation of new safety measures and the Grand Prix Drivers' Association to be re-established.

Background

Senna left his longtime team McLaren that he joined in 1988, to join Williams for 1994, replacing Alain Prost and being paired with Damon Hill. Williams was expected to again contend for the F1 world championship, as they had in the previous two seasons with Prost and Nigel Mansell, albeit with cars that had electronic aids no longer allowed in the new season.

On debut for his new team during the traditional pre-season testing at Estoril, Senna said of the Williams FW16:

I have a very negative feeling about driving the car and driving it on the limit and so on. Therefore I didn't have a single run or a single lap that I felt comfortable or reasonably confident. I am uncomfortable in the car. It all feels wrong. We changed the seat and the wheel, but even so I was already asking for more room. Going back to when we raced at Estoril last September (on testing the passive Williams at the same track 4 months later), it feels much more difficult. Some of that is down to the lack of electronic change. Also, the car has its own characteristics which I'm not fully confident in yet. It makes you a lot more tense and that stresses you.

The problems continued as the season commenced. Senna had had his worst ever start to a Formula One season, failing to finish or score points in the first two races (the Brazilian and Pacific Grands Prix), despite having taken pole in both. Benetton's Michael Schumacher was the championship leader entering the third race at Imola, with Senna trailing by twenty points.

1994 San Marino Grand Prix

Rubens Barrichello (pictured at the 1995 French Grand Prix) suffered a high speed crash at the Variante Bassa chicane

On the Friday before the accident, Senna's protegé, Rubens Barrichello, driving for the Jordan team, clipped a curb and crashed heavily at 140 mph (230 km/h) at the Variante Bassa chicane. Senna got out of his Williams car and went to the Medical Centre. Minutes after the accident, Barrichello regained consciousness and found Senna looking over him. After learning Barrichello had survived, Senna returned to his car and continued his practice session.

After the session concluded, he left his car and went to the Williams motor home to attend pre-arranged interviews for the press and told the attending journalists to wait one hour while he was checking car problems with his engineer, David Brown. Following the interviews, Senna continued his work with Brown for another two hours. Once he arrived back to his hotel in Castel San Pietro, Senna reportedly telephoned his girlfriend Adriane Galisteu and broke down into tears while recounting Barrichello's accident earlier that day.

On Saturday morning, Senna set a personal best time of 1m 22.03 seconds and agreed with teammate Damon Hill that the car had improved. Having been released from the Medical Centre, Barrichello told Senna he was flying back to England to watch the race on television.

Roland Ratzenberger was killed after colliding with a concrete wall at the Villeneuve Curve

In the afternoon, the second qualifying session began and 18 minutes into the session, Simtek driver Roland Ratzenberger crashed heavily at 314 km/h on the inside of the Villeneuve curve. Ratzenberger's car had just earlier become airborne, causing damage to the now partially detached wing, which prevented the driver from steering. After the impact with a concrete barrier, the car bounced off and rested in the middle of that section of the track. Senna saw the replays of the accident and rushed into the pitlane to get inside a course car. When he arrived, with Ratzenberger taken into an ambulance, Senna inspected the damaged Simtek. He then attended the circuit's Medical Centre where he learnt from friend and neurosurgeon Sid Watkins that Ratzenberger had died. When the two left the centre together, Watkins urged Senna to withdraw from the race, even from the sport entirely, and to go fishing instead (their joint hobby), to which Senna replied that he could not stop racing. Senna went back to the Williams garage where he summoned Patrick Head and Frank Williams, telling them of the situation and deciding to withdraw for the remainder of the Qualifying session.

Reportedly, Senna retired to his motor home where he broke down in tears and collapsed onto the floor. This had concerned Williams, who asked Betise Assumpção to arrange a meeting to discuss Senna's emotional state. Senna decided not to attend the post-qualifying press conference, leading the FIA to discuss but decide not to take disciplinary action against him. On the following day, however, Race Stewards called Senna out of his motor home to discuss his having commandeered a course car to visit Ratzenberger's crash site. A row ensued and Senna stormed off in disgust. The Stewards decided to take no action.

On Sunday morning, Senna was the fastest in the warm-up session by nine tenths of a second. Afterwards he spotted former McLaren rival Alain Prost sitting at a table. They talked together for 30 minutes, with Senna lobbying for Prost's help to improve the sport's safety, both agreeing to meet before the Monaco Grand Prix.

Next, Senna filmed an in-car lap of Imola for French television channel TF1, where he greeted Prost now working as a presenter for that channel: "A special hello to our dear friend Alain. We all miss you, Alain." Prost said that he was amazed and very touched by the comment.

At the drivers' briefing, Senna attended along with Gerhard Berger. Since he was unwilling to speak out due to the earlier row with race officials that had left him still fraught with emotions, Senna asked Berger to raise his concerns about the pace car's presence during formation lap, which had no role other than to promote the then latest Porsche 911. At the San Marino Grand Prix, this pace car was thus made to leave the grid in advance of the Formula One cars, instead of together.

Senna then met with fellow drivers to discuss the re-establishment of a drivers' group (the Grand Prix Drivers' Association) in an attempt to increase safety in Formula One. As the most senior driver, Senna offered to take the role of leader, starting with the next race event in Monaco. Niki Lauda suggested that Senna lead the group because of his strong personality, relative to the other drivers.

Racing crash

A map of the circuit per 1994 layout, with the Tamburello corner encircled.

At the start of the race, Pedro Lamy and JJ Lehto were involved in a serious accident spraying debris in to the crowd and injuring bystanders. Track officials deployed the Opel Vectra safety car, driven by Max Angelelli, to slow down the field and allow the removal of debris. The competitors proceeded behind the safety car for five laps. Being based on a family sedan and not relatively fast, Senna had pulled alongside the Vectra to gesture to its driver to speed up; this car was subsequently regarded as inadequate for the role and a cause of the alleged drop in tyre pressures of the following Formula One cars. 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 6, the race resumed and Senna immediately set a quick pace with the third-quickest lap of the race, followed by Schumacher.

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 spinning to a halt.

After Senna's car stopped he was initially motionless in the cockpit. After about ten seconds, as recorded by the close-up aerial footage, his head was seen to lift to the left before returning to its original position. Thereafter he did not move 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:

He looked serene. I raised his eyelids and it was clear from his pupils that he had a massive brain injury. We lifted him from the cockpit and laid him on the ground. As we did, he sighed and, although I am not religious, I felt his spirit depart at that moment.

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 was eventually lifted onto a truck and returned to the pitlane where officials impounded it. However, an unidentified person 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. Doctor Maria Teresa Fiandri, the emergency department head physician at the hospital who was off-duty and had been watching the race live from home with her sons, immediately left for the hospital and arrived at the same time as Senna's helicopter landed some 28 minutes after the crash. In her interview after 20 years, she confirmed that the blood loss suffered by Senna was due to a damaged superficial temporal artery and that, apart from his head injuries, Senna appeared serene and the rest of the body was intact. Dr Fiandri became responsible for providing medical updates to the media and public that had amassed at the hospital and, at 6:40pm, she announced that Senna was dead.

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.

Funeral

Monument to Ayrton Senna, Melinda Garcia's work, installed at the entrance of the tunnel under Ibirapuera Park, São Paulo, Brazil

Senna's death was considered by many of his Brazilian fans to be a national tragedy, and the Brazilian government declared three days of national mourning. Contrary to airline policy, Senna's coffin was allowed to be flown back to his home country not as cargo but in the passenger cabin of Varig's McDonnell Douglas MD-11 commercial jetliner (registration PP-VOQ (cn 48435/478)), accompanied by his younger brother, Leonardo, and close friends. Senna's coffin was covered with a large Brazilian flag.

The funeral was broadcast live on Brazilian television and an estimated three million people lined the streets of his hometown of São Paulo in what was widely accepted to be the largest recorded gathering of mourners in modern times. Many prominent motor racing figures attended Senna's state funeral, notably Alain Prost, Gerhard Berger, Jackie Stewart, Damon Hill, Thierry Boutsen, Rubens Barrichello (Ayrton's new protégé) and Emerson Fittipaldi who were among the pallbearers. However, Senna's family did not allow FOM president Bernie Ecclestone to attend, and FIA president Max Mosley instead attended the funeral of Roland Ratzenberger which took place on 7 May 1994, in Salzburg, Austria. Mosley said in a press conference ten years later, "I went to his funeral because everyone went to Senna's. I thought it was important that somebody went to his." Senna was buried at the Morumbi Cemetery in São Paulo. His grave bears the epitaph "Nada pode me separar do amor de Deus", which means "Nothing can separate me from the love of God" (a reference to Romans 8:38–39).

A testament to the adulation he inspired among fans worldwide was the scene at the Tokyo headquarters of Honda where the McLaren cars were typically displayed after each race. Upon his death, so many floral tributes were received that they overwhelmed the large exhibit lobby. This was in spite of the fact Senna no longer drove for McLaren and furthermore that McLaren, in the preceding seasons, did not use Honda power. Senna had a special relationship with company founder Soichiro Honda and was revered in Japan, where he achieved a near mythic status. For the next race at Monaco, the FIA decided to leave the first two grid positions empty and painted them with the colours of the Brazilian and the Austrian flags, to honour Senna and Ratzenberger.

Aftermath

Reactions

Some time later, Bob Jenkins of NASCAR on ESPN Speedworld relayed the news of Senna's death to American viewers during the 1994 Winston Select 500 at Talladega Superspeedway just as the drivers were coming to the restart. Dale Earnhardt, who won that race, dedicated his win to Senna. Also, CNN announced the news of Senna's death.

In Brazil, the country's television networks spent the rest of the day interrupting their normal programming schedules to announce Senna's death and replay his last interview, given to the media on the day before the accident. Many motor racing fans gathered outside of Maggiore Hospital to pay their respects to Senna, causing major traffic jams. Fans also gathered in the Williams F1 factory in Didcot where around 200 people attended with flowers laid on the front gates of the factory.

The Italian and Brazilian press were critical of the FIA for the rule changes that were enacted for 1994. Benetton driver, Schumacher, called for improvements in safety. BBC Sport commentator Murray Walker called Senna's death as the "blackest day for Grand Prix racing that I can remember".

Safety improvements

The layout of the circuit was changed after the two fatal accidents at the 1994 event.

On 3 May, the FIA called a meeting at the request of the Italian Automobile Club to review the events of the weekend. Later on, the governing body announced new safety measures for the next round in Monaco which included the entry and exit of the pitlane to be controlled by a curve to force cars to run at a reduced speed, no team mechanic would be allowed onto the pit lane surface except for when the drivers made a pit stop, and a draw would be arranged to determine the order in which cars make pit stops and be limited to emergencies with cars not taking on new tyres or allowed to refuel. On May 8, Federico Bendinelli, an official who worked at Imola inspected the road surface at Tamburello and declared it was safe. Williams ran tests on one of their rigs attempting to replicate Senna's accident from the data retrieved. They attempted to simulate a mechanical failure which had not proven conclusive.

At the next race in Monaco, retired world champion Niki Lauda announced the reformation of Grand Prix Drivers' Association (GPDA). The representatives elected were Lauda and active drivers Michael Schumacher, Gerhard Berger and Christian Fittipaldi. Following the tragic accidents during the season, the GPDA demanded the FIA improve the safety of Formula One. The FIA responded quickly and introduced changes to the regulations as follows:

For the Spanish Grand Prix,

• the size of diffusers would be reduced,
• the front wing end plates would be raised,
• the size of the front wing would be reduced.

Combined this would reduce the amount of downforce by about 15%.

For the Canadian Grand Prix,

• the lateral protection of the drivers' heads would be improved by increasing the height of the sides of the cockpit,
• the minimum weight of a Formula 1 car would be increased by 25 kg (changed to 15 kg by Canadian GP),
• the front wishbones would be strengthened to reduce the possibility of a front wheel coming loose and striking the driver,
• the cockpit would be lengthened to prevent drivers striking their head on the front of the cockpit,
• the use of a fuel pump would be introduced,
• the airboxes from the engines would be removed to reduce the airflow to the engines and thus decrease the power available.

Other changes included improved crash barriers, redesigned tracks and tyre barriers, higher crash safety standards, higher sills on the driver cockpit and a limit on 3-litre engines. The FIA immediately investigated the Autodromo Enzo e Dino Ferrari in Imola, and the track's signature Tamburello turn was changed into a left-right chicane as a result.

In February 1995, a 500-page report was handed over to prosecutors which suggested that a steering column had been the cause of Senna's crash.

Autopsy

During legal proceedings before the Italian courts on 3 March 1997, based on the expert testimony and evidence of the pathologist, Dr Cipolla, Senna's official time of death was recorded as 2:17pm on 1 May 1994, coinciding with cerebral death under Italian law, upon Senna impacting the Tamburello wall. The FIA and Italian motorsport authorities still maintain that Senna was not killed instantly, but rather died in hospital, where he had been rushed by helicopter after an emergency tracheotomy and IV administration were performed on track.

There is an ongoing debate as to why Senna was not declared dead at the track. Under Italian law, accidents resulting in a fatality must be investigated for any criminal culpability. The activities that cause the fatality, such as a sporting event, must be suspended forthwith and the scene of the accident secured.

The former Director of the Oporto (Portugal) Legal Medicine Institute, Professor José Eduardo Pinto da Costa, has stated the following:

From the ethical viewpoint, the procedure used for Ayrton's body was wrong. It involved dysthanasia, which means that a person has been kept alive improperly after biological death has taken place because of brain injuries so serious that the patient would never have been able to remain alive without mechanical means of support. There would have been no prospect of normal life and relationships. Whether or not Ayrton was removed from the car while his heart was beating or whether his supply of blood had halted or was still flowing, is irrelevant to the determination of when he died.

The autopsy showed that the crash caused multiple fractures at the base of the cranium, crushing the forehead and rupturing the temporal artery with haemorrhage in the respiratory passages. It is possible to resuscitate a dead person immediately after the heart stops through cardio-respiratory processes. The procedure is known as putting the patient on the machine. From the medical-legal viewpoint, in Ayrton's case, there is a subtle point: resuscitation measures were implemented.

From the ethical point of view this might well be condemned because the measures were not intended to be of strictly medical benefit to the patient but rather because they suited the commercial interest of the organisation. Resuscitation did in fact take place, with the tracheotomy performed, while the activity of the heart was restored with the assistance of cardio-respiratory devices. The attitude in question was certainly controversial. Any physician would know there was no possibility whatsoever of successfully restoring life in the condition in which Senna had been found.

Professor José Pratas Vital, Director of the Egas Moniz Hospital in Lisbon, a neurosurgeon and Head of the Medical Staff at the Portuguese GP, offered a different opinion:

The people who conducted the autopsy stated that, on the evidence of his injuries, Senna was dead. They could not say that. He had injuries which led to his death, but at that point the heart may still have been functioning. Medical personnel attending an injured person, and who perceive that the heart is still beating, have only two courses of action: One is to ensure that the patient's respiratory passages remain free, which means that he can breathe. They had to carry out an emergency tracheotomy. With oxygen, and the heart beating, there is another concern, which is loss of blood. These are the steps to be followed in any case involving serious injury, whether on the street or on a racetrack. The rescue team can think of nothing else at that moment except to assist the patient, particularly by immobilising the cervical area. Then the injured person must be taken immediately to the intensive care unit of the nearest hospital.

Rogério Morais Martins, creative director of Ayrton Senna Promotions (which became the Ayrton Senna Institute after Senna's death), stated that:

According to the first clinical bulletin read by Dr. Maria Teresa Fiandri at 4:30pm Ayrton Senna had brain damage with haemorrhaged shock and deep coma. However, the medical staff did not note any chest or abdomen wound. The haemorrhage was caused by the rupture of the temporal artery. The neurosurgeon who examined Ayrton Senna at the hospital mentioned that the circumstances did not call for surgery because the wound was generalised in the cranium. At 6:05pm Dr. Fiandri read another communiqué, her voice shaking, announcing that Senna was dead. At that stage he was still connected to the equipment that maintained his heartbeat.

The release by the Italian authorities of the results of Ayrton Senna's autopsy, revealing that the driver had died instantaneously during the race at Imola, ignited still more controversy. Now there were questions about the reactions of the race director and the medical authorities. Although spokespersons for the hospital had stated that Senna was still breathing on arrival in Bologna, the autopsy on Ratzenberger [who died the day before] indicated that his death had been instantaneous. Under Italian law, a death within the confines of the circuit would have required the cancellation of the entire race meeting. That, in turn, could have prevented Senna's death.

The relevant Italian legislation stipulates that when a death takes place during a sporting event, it should be immediately halted and the area sealed off for examination. In the case of Ratzenberger, this would have meant the cancellation of both Saturday's qualifying session and the San Marino Grand Prix on Sunday.

Medical experts are unable to state whether or not Ayrton Senna died instantaneously. Nevertheless, they were well aware that his chances of survival were slight. Had he remained alive, the brain damage would have left him severely handicapped. Accidents such as this are almost always fatal, with survivors suffering irreversible brain damage. This is a result of the effects on the brain of sudden deceleration, which causes structural damage to the brain tissues. Estimates of the forces involved in Ayrton's accident suggest a rate of deceleration equivalent to a 30 metre vertical drop, landing head-first. Evidence offered at the autopsy revealed that the impact of this 208 km/h crash caused multiple injuries at the base of the cranium, resulting in respiratory insufficiency.

There was crushing of the brain (which was forced against the wall of the cranium causing oedema and haemorrhage, increasing intra-cranial pressure and causing brain death), together with the rupture of the temporal artery, haemorrhage in the respiratory passages and the consequent heart failure.

There are two opposing theories on the issue of whether the drivers were still alive when they were put in the helicopters that carried them to hospital. Assuming both Ratzenberger and Senna had died instantaneously, the race organisers might have delayed any announcement in order to avoid being forced to cancel the meeting, thus protecting their financial interests.

Had the meeting been cancelled, Sagis – the organisation which administers the Imola circuit – stood to lose an estimated US$6.5 million.

Italian prosecution

The Williams team remained entangled for many years in Italian criminal court proceedings, which had been instituted by prosecutors following manslaughter charges being laid against key team officials. The original trial in 1997 concluded with acquittals after the judge ruled that the prosecution had failed to prove its case, but a retrial was ordered by Italy's highest court. Thus, on 13 April 2007, the Italian Supreme Court of Cassation delivered its own verdict (number 15050) stating that: "It has been determined that the accident was caused by a steering column failure. This failure was caused by badly designed and badly executed modifications. The responsibility for this falls on Patrick Head, culpable of omitted control". Head, however, was not arrested since the Italian statute of limitations for culpable homicide was 7 years and 6 months, and the verdict was pronounced 13 years after the accident.

The criminal charges focused on the car's steering column, which was found to have sheared off at a point where a modification had been made. The prosecution alleged that the column had failed causing the accident and the Williams team conceded to this failure, but only as caused by the crash impact. Senna had not liked the position of the steering wheel relative to his seating position and had asked for it to be changed. Patrick Head and Adrian Newey satisfied Senna's request by having the FW16's existing shaft cut and extended with a smaller-diameter piece of tubing that was welded together with reinforcing plates. The modification was carried out in this manner as there was insufficient time to instead manufacture a longer steering shaft in time for the race.

A 600-page technical report was submitted by Bologna University under Professor of Engineering Enrico Lorenzini and his team of specialists. The report concluded that fatigue cracks had developed through most of the steering column at the point where it had broken. Lorenzini stated: "It had been badly welded together about a third of the way down and couldn't stand the strain of the race. We discovered scratches on the crack in the steering rod. It seemed like the job had been done in a hurry but I can't say how long before the race. Someone had tried to smooth over the joint following the welding. I have never seen anything like it. I believe the rod was faulty and probably cracked even during the warm-up. Moments before the crash only a tiny piece was left connected and therefore the car didn't respond in the bend."

An analysis of the onboard camera video was submitted by Cineca, which tracked the movement of the steering wheel during the race. Having rotated in a fixed arc during the previous laps, during the final seconds a yellow button on the wheel moved several centimetres away from its normal trajectory, with the steering wheel tilting in its own plane, indicating a breaking steering column. Williams introduced its own video to prove the movement was normal in which David Coulthard manhandled an FW16B steering wheel, the effort required to deflect the wheel termed as "quite considerable". Michele Alboreto testified that the steering wheel movement was abnormal, stating that the video "proves that something was broken in Senna's Williams. No steering wheel moves a few centimetres."

During the trials, a regional technical commissioner named Fabrizio Nosco testified that both of the vehicle's black boxes were intact, except for minor scratches. He said "I have seen thousands of these devices and removed them for checks. The two boxes were intact, even though they had some scratches. The Williams device looked to have survived the crash." In a move that apparently breached FIA regulations, Charlie Whiting, an FIA official, handed the black boxes to Williams before the regulating body's own investigation into the accident. Williams claimed the black boxes were unreadable, and the boxes returned for the court proceedings were indeed unreadable, a full month after the accident.

On 16 December 1997, Frank Williams and five others were acquitted of the charges, ending the threat of a boycott of Formula One in Italy. In a 381-page ruling, Judge Antonio Constanzo concluded that steering column failure was the probable cause of Senna's accident, however, there was no proof of negligence on the part of Head or Newey, or that they had designed the modifications in the first place. On November 22, 1999, an appeals court upheld the acquittals, rejecting a request from prosecutors to give one-year suspended sentences to Head and Newey.

In April 2002, Senna's FW16 chassis number 02 was returned to the Williams team. The team reported that the car was in an advanced state of deterioration and was subsequently destroyed. Senna's helmet was returned to Bell, and was incinerated. The car's engine was returned to Renault, and its fate is unknown.

In January 2003, the Italian Supreme Court reopened the case, ruling that "material errors" had been made, referring it to the Bologna court of appeal. On 27 May 2005, the court gave a full acquittal to Adrian Newey, while the case against Head was "timed out" under a statute of limitations. On 13 April 2007, the Italian Supreme Court rejected a request for the acquittal of Patrick Head, ruling Head responsible for "badly designed and badly executed modifications", and that the event was "foreseeable and preventable".

In May 2011, Williams FW16 designer Adrian Newey expressed his views on the accident: "The honest truth is that no one will ever know exactly what happened. There's no doubt the steering column failed and the big question was whether it failed in the accident or did it cause the accident? It had fatigue cracks and would have failed at some point. There is no question that its design was very poor. However, all the evidence suggests the car did not go off the track as a result of steering column failure... If you look at the camera shots, especially from Michael Schumacher's following car, the car didn't understeer off the track. It oversteered which is not consistent with a steering column failure. The rear of the car stepped out and all the data suggests that happened. Ayrton then corrected that by going to 50% throttle which would be consistent with trying to reduce the rear stepping out and then, half-a-second later, he went hard on the brakes. The question then is why did the rear step out? The car bottomed much harder on that second lap which again appears to be unusual because the tyre pressure should have come up by then – which leaves you expecting that the right rear tyre probably picked up a puncture from debris on the track. If I was pushed into picking out a single most likely cause that would be it."

Alternative theories

Former Formula 1 driver Nelson Piquet said Senna was under pressure and suffering emotional stress in his last days. In 1994, Senna was dating the model Adriane Galisteu for almost a year. In the weekend of the Grand Prix, she was in Portugal and his old girlfriend Xuxa pursued him in Imola trying to break his relationship with Adriane and convince him to return to her. A cassette tape given to Senna by his brother Leonardo days before the accident, allegedly contained an Adriane conversation with her ex-boyfriend. This, together with Rubens Barrichello's accident and the death of Roland Ratzenberger could have stressed Senna, as seen in his last appearance in the grid, minutes before the accident. The retired Alain Prost said in the documentary Senna there was something wrong with Senna when they met both two weeks before and at the Grand Prix. Theories about a possible suicide also emerged in international press, though they were quickly rejected.

See also

• List of fatal Formula One accidents
• 1994 San Marino Grand Prix
• Ayrton Senna