On Wednesday, the FIA confirmed it would introduce the Halo cockpit protection concept in Formula One next year. The decision was based on Halo presenting "the best overall safety performance" according to the FIA's five years of research into increased frontal head protection.
The device is destined to split opinion ahead of its full introduction next year as it looks set to change the aesthetics -- and arguably the open-cockpit DNA -- of Formula One racing indefinitely. Below is a guide to what the Halo is, why it was introduced and how a device aimed at improving safety has become so controversial.
The background
A focused push for increased cockpit protection started in 2009 when Henry Surtees, son of former world champion John, was killed by a loose wheel in a Formula 2 race. Just over a week later, Felipe Massa suffered life-threatening injuries when hit in the head by a loose spring during practice for the Hungarian Grand Prix.
The issue of head protection returned to prominence again after Jules Bianchi's fatal collision with a recovery vehicle at the 2014 Japanese Grand Prix, although a subsequent investigation found cockpit protection would have made no difference to his injuries. In 2015, former F1 driver Justin Wilson was killed by a flying piece of debris from another car during an IndyCar race, further underlining the dangers of open-cockpit racing and prompting the Grand Prix Drivers' Association (GPDA) to call for extra cockpit protection in F1.
The FIA, already several years into its research of additional head protection, put a provision for Halo in the 2017 technical regulations and started conducting on-track tests in early 2016. However, amid concerns that Halo was being rushed through without the necessary real-world testing at different types of circuits, F1's Strategy Group agreed in July 2016 to postpone Halo's introduction until 2018 and conduct further tests during Friday practice sessions that year.
Despite a series of successful tests at the end of 2016, a meeting of the Strategy Group in April this year decided that the FIA should shift its priority to a new device known as the Shield. The Shield made its first track test on Friday at the British Grand Prix, but the run was cut short after Sebastian Vettel reported distorted vision through the curved windscreen, claiming it made him feel dizzy. With time running out before the teams needed a final decision for their 2018 car designs, Halo became the only viable option for the FIA ahead of this week's meeting of the Strategy Group. Arguably the cars could have been left without additional head protection in 2018, but that would have left the FIA vulnerable to legal implications if it was proven that a driver's death or injury could have been prevented by Halo.
The device
The Halo concept was first proposed by Mercedes after the FIA had started its research into rudimentary front roll cages. The first Halo prototype -- made of steel -- underwent static tests at RAF Bentwaters in 2015 and performed well against a 20 kg tyre fired from a compressed nitrogen-powered cannon at speeds of 225 km/h. A steel prototype shrouded in carbon fibre was then track tested by Ferrari during winter testing in February 2016, with drivers reporting acceptable levels of visibility despite the vertical pylon and protective section directly in front and above the cockpit.
At the 2016 Austrian Grand Prix a lighter, stronger prototype made of titanium was introduced known as Halo 2. One of the notable changes was making the arc of the Halo wider in order to improve visibility and eradicate the risk of a driver hitting his head on the device during an impact. Extrication tests took place in the Red Bull Ring pit lane before it was run on track at the following round in Silverstone. A series of tests followed during Friday practice sessions so that all drivers on the 2016 grid completed at least one lap with the prototype attached.
The FIA is now hoping to work with teams to make further modifications to the concept before it is introduced as an integral part of 2018 chassis design.
Arguments for and against
The debate around Halo has centred around five points: safety, aesthetics, visibility, driver extrication and, in a wider argument, the DNA of open-wheel racing itself. Lewis Hamilton memorably called the Halo device the "worst looking mod in Formula One history" when it was first unveiled, but he changed his view after the FIA presented the drivers with the findings of its research at last year's Hungarian Grand Prix.
"I paid close attention to the great briefing we were given on it," Hamilton said. "I take safety very, very seriously. The interesting thing is that while the Halo system does not look great or in the racing spirit, the chances are 17 per cent better of saving the driver's life. But it can still be improved so at some stage we will have canopies and then it will be 100 per cent."
Visibility
Despite the bulky look of the Halo, very few drivers have complained about visibility issues while testing it. There were fears that circuits with extreme elevation change, such as Spa-Francorchamps, might leave the drivers with a blind spot directly ahead of them as they approached a hill, but after driving the Halo 2 prototype during practice for last year's Belgian Grand Prix, Mercedes driver Nico Rosberg said it made no difference.
"No problem at all, you don't even notice the top part," he said. "I think they can even come down with that because LMP1 is lower anyways. So for sure they could go lower."
Nico Hulkenberg, who was initially against the Halo, added: "It was a weird feeling. I don't know, it felt weird. To have something there which limits you going forward was obviously a new experience. I have to say the visibility wasn't too bad. I don't think that was a big issue but certainly it will take time to get used to."
There are still some drivers that are against the Halo -- most notably Romain Grosjean who recently said he "hated it" and it made him "feel sick" -- but as a collective body the Grand Prix Drivers' Association have supported the FIA's push for extra cockpit protection.
Driver extrication
Driver extrication was an early criticism levelled at increased cockpit protection, with critics suggesting the additional struggle of getting out of a rolled car with Halo attached would act as a safety hazard in itself. However, the FIA is happy with the extrication tests which have taken place so far, saying the benefits outweigh any negatives.
After his terrifying barrel-roll accident in Australia last year, Fernando Alonso said a Halo would have been "very welcome" regardless of how long it took him to get out of the car. A subsequent study by the FIA revealed that the Halo would not have prevented Alonso climbing out and would actually create "breathing space" for the driver to work his way free from the cockpit.
Aesthetics v safety
The final and most contentious point concerns the look of an F1 car fitted with Halo. Niki Lauda said last year that the introduction of Halo risked destroying the DNA of Formula One, which has featured open cockpits since the inaugural world championship event in 1950. However, Formula One cars have undergone many visual changes in the name of safety in past decades and all of them have eventually been accepted as the norm.
In 1996 a foam cockpit surround was introduced for the first time and, despite changing the look of the cars significantly, it saved its first life within a year of its introduction. Former F1 doctor Sid Watkins presented research into Jos Verstappen's accident at the 1996 Belgian Grand Prix in his book Beyond the Limit, which found that without the extra protection of the cockpit surround, Verstappen's head would have been exposed to forces capable of inducing life-threatening injuries. Instead Verstappen retained consciousness throughout the accident and was "merely stunned and slightly unsteady on his feet" when he got out of the car. Put simply, without the introduction of the extra head protection in 1996, it is unlikely Verstappen would be alive today and therefore also unlikely his son Max would be on the grid in 2017.
There is still some debate as to what sort of accidents the Halo is designed to protect against and what sort of accidents would occur regardless, but with the FIA's research finding that the chances of survival are 17 per cent greater with Halo attached, the additional protection is too significant to ignore.
Alternatives
Although Halo has been chosen by the FIA for introduction next year, the governing body has been open to alternative solutions throughout its research. Red Bull tabled a concept of its own in early 2016 known as the Aeroscreen, which debuted at the Russian Grand Prix and featured a protective windscreen in front of the cockpit. However, Halo was closer to realisation when the FIA made a decision in May 2016 to throw its resources behind one concept and development of the Aeroscreen was dropped.
A third solution emerged earlier this year, known as the Shield, which was closer in concept to the Aeroscreen than the Halo. The Strategy Group agreed to throw F1's full support behind the Shield, which was considered to be a more visually appealing concept, but its future hinged on its first on-track outing at Silverstone last week. That test lasted just one lap before Vettel returned to the pits complaining of distorted vision, aerodynamic side-effects and dizziness.
"We had a run planned with it, but I didn't like it -- especially looking forwards because of the curvature," Vettel said. "It had quite a lot of distortion and I got a bit dizzy. There was a lot of downwash coming off the back of my helmet and pushing my head forward, so we decided to take it off."
Less than a week after that initial test, the FIA confirmed Halo -- not the Shield -- would be introduced next year.