Deep shadows stretch across Formula One as a new season is marked by the 20th anniversary of Ayrton Senna's death and continuing concern for Michael Schumacher. The German driver, who won a record seven world championships, remains in a coma three months after he suffered a skiing accident in France. Despite hopeful statements this week Schumacher's future seems bleak – and lies in murky contrast to the supreme figure who raced ahead of Senna in the last weeks of the Brazilian's life.

Senna won three titles and he is still revered for his romantic intensity and brilliant driving. His almost mythic status is about to be rekindled by bruising memories of his death at Imola, in 1994, when he struggled to keep pace with Schumacher. Their differences and similarities are described vividly by Damon Hill – Senna's team-mate at Williams and the British driver who emerged as the greatest threat to Schumacher as he closed in on his first world title. Hill was one point behind Schumacher when they began the final race of 1994's sombre season. Yet his hopes of winning the title ended when Schumacher appeared to cause a deliberate collision.

In 1996, though, Hill emulated his father, Graham, in becoming world champion. That victory was the culmination of three difficult years for Hill as, in the wake of Senna's death, his life and Formula One changed forever.

Hill is relieved racing is now a lower-risk business but he makes a telling point when wondering whether the sport features similarly compelling characters. "Can we say there is the same gravitas to Formula One today?" he asks during a long and absorbing interview.

I offer a layman's perspective that F1, despite its current unpredictability, appears to lack drivers with the complexity and depth of Senna and his predecessors. "It's an interesting comment and I think people feel that. Maybe we have to ask why there is not so much admiration and respect today. There's a lot of talent and experience but drivers are being cloaked by the sport in this media-mad world. When you talk about the philosophical, layered characters of Senna, [Niki] Lauda and [James] Hunt I don't think we've got anyone like that today. It comes back to the life-and-death question."

Without the existential threat of danger and death, have drivers become bland in a sponsor-driven business? "I think so. I watched this fascinating documentary about Peter Revson [who died before the South African grand prix in 1974]. Part of the reason they raced then was because it was so dangerous. I say 'they' because I'm not sure I would've wanted to be a racing driver in the 1970s. It was grim. But that risk kicked something into life that's not there today."

Hill's comments are persuasive for they are framed by his certainty that, after Imola, racing had to change. He is also quietly emphatic that he would not have won the drivers' title had Senna lived. "I was uncomfortable when I won the BBC's Sports Personality of the Year [in 1994 and 1996]. As a racing driver I wanted to be at the front but I was thrown into that situation. It was highly unlikely I would've held Ayrton at bay."

Yet no other driver was as close to Senna and Schumacher during the pivotal moments of that tragic season. Apart from being Senna's team-mate he pushed Schumacher hard and sometimes, most memorably at a rain-sodden Suzuka, out-drove him. "At Suzuka I had to win to stay in the championship," Hill remembers. "I drove at a level I never reached before or after again. Experience counts for a lot but I didn't have any. I only got into Formula One aged 31. Look at Kimi Raikkonen and Jenson Button. They're 34 and began in F1 in 2000 and 2001. I did pretty well against people my age but I raced Michael Schumacher with no experience and I was almost 10 years older. Maybe I didn't do so badly."

In keeping with his modest character and his current role as an expert analyst for Sky Sports, Hill prefers to consider the wider ramifications of 1994 and how that desolate weekend changed F1 so profoundly – for Roland Ratzenberger, the Austrian driver, lost his life the day before Senna. "We had to wrestle with the question of 'How do we justify this sport?' And the answer is we can't unless we do something about safety. Max Mosley [the former FIA president] and Sid Watkins [then F1's chief medical officer] worked very hard to encourage the application of the genius of F1 technology to safety.

"Some people are ambivalent but the sport can be proud of changing its approach to risk. It used to be very cavalier – and we had that Lauda and Hunt approach. In my father's day it was even worse. I was 15 when my dad died [in a plane crash] but lots of his friends were lost on the track. I learned from my dad how to cope with tragedy. The death of Roland and Ayrton took people's breath away because they weren't used to that experience – Elio de Angelis was the last driver to have been killed, eight years earlier. But for my mum it was regular occurrence – as shocking and appalling as it was. There was nothing heroic about it but that's how the sport was. But, at Imola, the whole weekend seemed to be a crucible for everything that could go wrong. There was a lot of fear and trepidation."

Hill remains convinced that Senna, who had failed to score a point in a new car in the championship's opening two races, made a simple human error as he approached the Tamburello corner too fast. "This is the lesson of Imola," Hill suggests, recalling that Autosport's cover that week had asked whether Senna could "stand the heat" of Schumacher's challenge. "People are always looking for a reason for what happened. There are lots of reasons but you can't forget that Senna had left the team [McLaren] which had given him the bulk of his success. He was settling into a new team and we were having setup issues with the car. And then, of course, you've got this new guy, Michael Schumacher, running rings around him. Maybe, at 34, he felt it slipping away.

"It was very difficult for Ayrton. In 1993 he had produced what was described as the greatest race anyone had ever driven – at Donington – where he had made everyone else look ridiculous in the wet. So he'd underlined his credentials as this living god in a racing car and then Schumacher turned up. At Imola Ayrton was pondering who Michael Schumacher was – as much as he was reflecting on his own career."

Senna was also distressed by Ratzenberger's death. "Ayrton was incredibly sensitive and he was conflicted. I think he wanted to know what life meant – and death is a part of life. Our lives were on the line and so he wanted to know what happened to Roland. That's why he was exceptional. Most drivers say: 'I don't want to be dealing with that.' But Ayrton took his responsibilities seriously.

"And he really was a mythic figure in his own lifetime. The Japanese and the Brazilians saw him as a god. His passion was undeniable and I sincerely believe he wanted to make the world a better place. Ayrton was heroic in that sense because he felt deeply and compassionately and he was struggling as to how best he could use his position to help people."

Senna still ignored his own failings. Hill laughs as he remembers, in 1993, "being called into Ayrton's motorhome because he hadn't approved of what I'd done on the first lap of a race. It was like being summoned by the head. I walked in, cheeky as you like, when I should have been kissing his feet. But I thought: 'This is too good to be true – being told by Senna how to drive safely.' I could see the irony even if he couldn't. In a sly way he was advising me that racing was dangerous. But great sportsmen like Senna are blind to themselves. They believe that only they can do what they do."

Did Schumacher have that same sense of entitlement? "Yes – except that Michael was much cooler about his racing. Michael didn't exude passion like Ayrton. He was quite clinical but he had oodles of confidence. The difference was that Ayton seemed to need battles to galvanise him – with Alain Prost and even his own team. Michael worked instead with his team and used their talents to help him."

Schumacher was still intent on undermining his rivals – and in 1994 he insisted haughtily that: "Hill is not world-class." Hill winces. "That one still hurts," he says with a rueful smile. "Part of me thinks he was probably right."

A fierce competitor like Schumacher, surely, would not have made such a scathing comment had he not considered Hill a serious threat. "That's what Georgie [Hill's wife] always said. But it does undermine you because it plants the seed in the minds of those who employ you."

Even when Hill was about to win the 1996 world championship, Williams told him they would dispense with his services. But I remind the 53-year-old how shocked Schumacher looked when Hill outdrove him in Japan in 1994. "It's difficult to say this when he's in hospital now but, at Suzuka, he'd had to pack away all his balloons and party-poppers."

Everything hinged on that final race in Adelaide but, at the end of a traumatic season, Hill was denied the chance to beat Schumacher. The German's car careered into a wall while leading and, as Hill tried to overtake him, it seemed as if Schumacher turned into his path to force a joint retirement. "Michael came from a school of racing influenced by Ayrton's career when he managed to determine the outcome of a championship with a crash. In karting that was seen as a legitimate tactic. At the time I thought I'd screwed up. But when you look at the replays it's clear he must have been aware his car was damaged."

Did Schumacher ever discuss the incident with Hill? "No. But we did have a giggle when I was a steward at Monaco in 2010 and we had to make a ruling against him. I had death threats after that – but I actually defended Michael."

Hill endured testing times alongside Schumacher and Senna but his respect for their lofty place in racing history is obvious. And so it is understandable why we spend an hour reflecting on their achievements, and separate tragedies, before turning to this season. "F1 is in a state of flux at the top. I would say anyone in a Mercedes [meaning Lewis Hamilton] looks good. The intriguing thing will be whether the new regulations suit Lewis's style. But after all the debate, about him moving to a new team last year, this looks a very insightful move. He looks immensely strong."

Adrian Newey, who designed the Red Bull cars that turned the past four years into a procession, was at Williams when Senna lost his life. That death scarred the British designer but his genius remains intact. Does Hill expect Newey to solve Red Bull's problems? "Knowing Adrian, he will have made the packaging of the ancillaries to the new power unit so stringent it's difficult to get it to work at the moment. But when it does they'll be well up front again. Sebastian Vettel's enjoyed the luxury of domination so this will be a big test for his temperament."

There is interest again in Formula One but, for Hill and many more of us, the lost and complex shadows of Senna and Schumacher will be much harder to forget in this dark anniversary year.

Sky Sports F1 will screen all 19 grand prix weekends live on TV, Sky Go and Now TV