No driver has left as lasting a legacy as the great Ayrton Senna, a man remembered for fearless racing, infectious charisma and his death which shook Formula One to its core.

The Sao Paulo-born triple world champion was one of the most celebrated F1 racers in history, winning drivers’ championships in 1988, 1990 and 1991 with McLaren.

A man of contrasts, Senna was a ferocious competitor – often criticised for his role in a number of high-profile crashes and taking big risks on the track – but also a contemplative sportsman who could eloquently and poetically converse about his profession.His turbulent rivalry with McLaren team-mate Alain Prost was the stuff of driving legend, with their years as both team-mates and opponents characterised by acrimonious exchanges and crashes.

Senna’s last ever win was at the 1993 Australian Grand Prix in Adelaide, which has since renamed its circuit’s first chicane the “Senna Chicane”.

Tragically, his legacy was immortalised after his fatal crash in the San Marino Grand Prix on May 1, 1994, having spent the latter stages of his career in pursuit of a safer racing environment for drivers, track staff and spectators.While not unaccustomed to death on the track, Formula One was sparked into radical action following Senna’s demise, prompting an unprecedented development in driver safety technology in the world’s fastest and most dangerous sport.

After a rocky start to the 1994 season, Senna claimed pole position at Imola, but was furious at events that unfolded in the lead-up to qualifying. On the Friday, Senna’s compatriot Rubens Barrichello withdrew after suffering a broken nose and arm in a serious accident where his airborne Jordan car hit a tyre-wall and fence.

The next day, disaster struck as Austrian rookie Roland Ratzenberger was killed instantly after hitting a barrier following a front-wing failure. A distressed Senna visited the site of the crash that day with the FIA’s medical chief professor Sid Watkins

Watkins suggested to Senna that he retire to “take up fishing”, but Senna insisted that he could not stop racing.Senna himself had struggled with his car despite claiming pole, complaining about handling and poor performance after engineering adjustments.He spent the morning of race-day with former rival Prost to discuss the re-establishment of the Grand Prix Drivers’ Association (GPDA) in a bid to improve safety in the sport.

Following a safety-car interruption after an accident between JJ Lehto and Pedro Lamy – where debris landed in the grandstand and injured nine people – Senna reclaimed the race lead to set a quick pace ahead of Michael Schumacher.

But as Senna rounded the Tamburello corner on the seventh lap, his car left the line and ran straight into a concrete retaining wall at approximately 233kph. Telemetry data revealed Senna had applied the brakes for a full two seconds before the crash.

With the red flag shown, Watkins arrived inside two minutes of the crash and performed an on-site tracheotomy, later reporting the driver had lost approximately 4.5 litres of blood. Senna was airlifted to a nearby hospital where he was pronounced dead hours later after suffering a ruptured temporal artery, skull fractures and brain injuries.

The exact cause of death is believed to be from a piece of upright assembly penetrating Senna’s visor above his right eye, after a front wheel and suspension struck the driver on the right side of his helmet.

The years that preceded the ill-fated 1994 season were characterised by a general complacency by organisers, who assumed the strength of the carbon-fibre chassis was enough to protect drivers, despite a series of recent near-misses.

The belief that no more drivers would die in Formula One emerged after eight years without a fatality in an era which saw speed increase, tyre widths reduced and driver aids removed.

The confidence in the chassis was high enough for the FIA to ban almost all performance-enhancing electronic technology, including traction control, ABS-assisted brakes and automatic gears. This resulted in more skittish vehicles on the track as drivers jostled with cars high in horsepower but low in stability. Those measures proved to be folly as two drivers (Lehto and Jean Alesi) were involved in near-fatal accidents in 1994’s preseason, as well as Barrichello’s accident at Imola.

Senna’s death sparked sweeping changes in Formula One. Major cuts were made to engine power, the minimum weight of cars was increased, crash barriers were improved, tracks were redesigned and much higher safety standards were implemented.

The production standard for helmets, as well as crash tests, became much stricter, before data recorders were eventually installed in all cars for precise accident analysis.

Senna’s reforming of the GPDA on the day of his death would also bring about the mandatory inclusion of the Head and Shoulder Neck Support (HANS) device in 2003.

Engine capacity was reduced from 3500cc to 3000cc (and has been reduced further since) in a bid to further slow cars, and cockpits were elongated to diminish the chance of a driver hitting his head in an accident. Other improvements since have included the raising and reduction in size of the front wing end plate, smaller diffusers and the strengthening of the front wishbone suspensions.

Imola’s signature Tamburello turn, which claimed Senna’s life, has since been changed into a left-right chicane.

While Formula One had made safety changes in the past after driver deaths, the difference was the idea of a driver dying in an F1 car had now become untenable.

The change in philosophy is as strong today as it was in the aftermath of 1994, but former FIA president Max Mosley has warned against a repeat of the complacency that characterised the early 1990s.

“It’s quite true to say that it’s good to focus on the fact that we’ve done 20 years. But one always has this feeling ‘don’t tempt fate’,” Mosley told Reuters.

“You have this feeling that if you start boasting about that, it will come back and bite you.

“That (Imola weekend) was the catalyst for change on the roads that has literally, without question, saved tens of thousands of lives.

“It is the truth. Without that catalyst, we would never have gone to Brussels. We would never have the Euro NCAP (New Car Assessment Programme), the crash testing, we wouldn’t have got the legislation through the European Commission that has upped the standards of safety.

“You know thousands of people walking around, happy, alive, uninjured would be dead if it weren’t for what was done. And all of that started with Ayrton’s accident. That to me, when I sit down in my rocking chair in another few years, is the thing that really matters.”

Early days: from go-karts to F1 debut

Senna’s first racing kart was a small 1HP go-kart built by his father with a lawnmower engine. He entered his first karting competition aged 13, starting his first race on pole against rivals several years older than him. Supported by his father, Senna won the South American Kart Championship in 1977, and finished runner-up in the 1979 and 1980 Karting World Championship, before moving to England in 1981.

After testing for Formula One teams in 1984 – where he posted times several seconds faster than a host of number-one drivers – Senna eventually signed for Toleman, making his debut at the 1984 Brazilian Grand Prix.

Senna finished his debut season in ninth spot in the championship, having claimed podium finishes in Monaco, Portugal and the British Grand Prix, all despite driving for a relatively new team with uncompetitive tyres.

Before the end of the season, Senna bought out his contract and signed for Lotus, with whom he claimed his first ever pole in the second race of the 1985 season – the Portuguese Grand Prix. He would convert that pole into a first career race win in F1. He would only finish fourth overall that year, but developed a reputation as the fastest man on the track after picking up seven poles that season.

The rivalry with Alain Prost

Senna would briefly lead the 1986 championship before falling behind eventual champion Alain Prost of McLaren, again finishing fourth overall.

In 1988, Senna joined McLaren and reigning champion Prost in what would become one of the fiercest rivalries in motorsport history. The discord between the two reached a crescendo at the Portuguese Grand Prix, when a risky Senna swerve at the head of the pack blocked Prost, nearly forcing the Frenchman into the pitwall.

Prost was angered by the manoeuvre, but Senna escaped with a warning from the FIA. The pair went on to win 15 of the season’s 16 races, with Senna taking out his first world championship title. 1989 was characterised by off-track warfare between the two, with Prost accusing Senna of disobeying pre-race agreements. Senna briefly led the championship that year before Prost overtook his team-mate.

That season culminated in a dramatic crash between the pair at the Suzuka Circuit in Japan, which saw Prost cut Senna off at a corner, only to interlock the two cars’ wheels together, sending both drivers spinning off the track.

Senna got back into the race thanks to a push start, but was disqualified following a stewards meeting after the race, giving Prost the title. Senna was furious, claiming the FIA’s French president Jean-Marie Balestre wanted to see his compatriot Prost take the championship.

After colliding in 1989, Prost (now driving for Ferrari) and Senna repeated the trick in 1990, colliding in the opening lap at Suzuka, spinning out of the race. The result this time saw Senna become world champion – his second F1 title.

In 1991, Senna became the youngest-ever three-time world champion, claiming seven wins and again securing the championship in Japan. The following year was one of frustration as McLaren struggled to compete with Williams’s superb FW14B car.

Out of contract in 1993, Senna eventually signed on with McLaren on a race-by-race basis, finishing second in the championship to Prost, who had joined Williams after a one-year sabbatical.

Prost decided to retire at the end of the 1993 season, opening up the door for Senna to join Williams in 1994. Due to the ban on active suspension, traction control and ABS, Williams’s new FW16 car was immediately inferior to its predecessors. Senna was immediately suspicious of his new ride, saying he was not confident in the car’s “characteristics”, before predicting a season with plenty of accidents. After spinning out in the Brazilian Grand Prix and carding a DNF in the Pacific Grand Prix, Senna’s last race would be in the San Marino Grand Prix, which ultimately claimed his life.

Personal legacy: racing philosopher, champion of the poor

In numerous polls, Senna has been voted as the greatest Formula One driver of all time by past and present drivers, journalists and fans. But his legacy stretches beyond the race track – most tellingly in his home country of Brazil, where he is afforded almost demi-god status. A devout Catholic, Senna’s unabashed faith in God struck a chord with Brazil’s millions. Having grown up in Sao Paulo, Senna often spoke out against the sheer divide between the country’s rich and poor.

“Wealthy men can’t live in an island that is encircled by poverty,” he said in a 1993 interview.

“We all breathe the same air. We must give a chance to everyone, at least a basic chance.”

Senna’s concern for Brazil’s poor saw him establis82h the Instituto Ayrton Senna (Ayrton Senna Institute), which aims to bring Brazilian children out of poverty in cooperation with business, government and NGOs. Senna’s sister Viviane, who heads the Institute, has said her brother was equally determined in his racing as he was in wanting “to achieve something for Brazil”.

Senna also retained a very philosophical view on racing, which took on a more serious tone as he became more concerned over driver safety.

His brazen will to win, which resulted in so many of his crashes with Prost, saw his rival accuse him of believing he was immortal on the track: “He thinks he can’t kill himself,” Prost remarked, “because he believes in God, and I think that’s very dangerous.” But Senna rebuked this, saying: “These things bring you to reality as to how fragile you are; at the same moment you are doing something that nobody else is able to do.

“The same moment that you are seen as the best, the fastest and somebody that cannot be touched, you are enormously fragile.

“These two extremes are feelings that you don’t get every day. These are all things which contribute to – how can I say? – knowing yourself deeper and deeper. These are the things that keep me going.”

By James Maasdorp