In 2009, two major accidents occurred in top-level FIA open-wheel series: the fatal accident of Henry Surtees at the Brands Hatch round of the 2009 Formula 2 season and the accident Felipe Massa sustained during qualifying at the 2009 Hungarian Grand Prix. These accidents led to calls for additional cockpit protection.
Initially, the FIA looked into the development of closed cockpit systems, visors, and forward roll structures. Tests demonstrated that the halo system can significantly reduce the risk of injury to the driver. In many cases, the system was able to prevent the helmet from coming into contact with a barrier when checked against a series of accidents that had occurred in the past. During the study of collisions with vehicles and debris it was found that the halo was able to deflect large objects and provide greater protection against smaller debris. The halo system is not developed by the teams, but is manufactured by three approved external manufacturers chosen by the FIA and has the same specification for all vehicles. In a simulation performed by the FIA, using data from 40 incidents, use of the system provided a 17% increase in the survival rate of the driver.
The device consists of a bar that surrounds the driver's head and is connected by three points to the vehicle frame. The halo is made of titanium and weighed around 7 kilograms (15 lb) in the version presented in 2016, then rose to 9 kilograms (20 lb) in 2017.
In August 2017, the Dallara F2 2018 was presented and was the first to install the halo system. The SRT05e Formula E car presented in January 2018 had a halo. In November 2018, the 2019 FIA Formula 3 car, which was unveiled in Abu Dhabi, installed the halo as well. Beginning in 2021, the Indy Lights' IL-15 began using the halo.
As an alternative to the halo system, Red Bull Advanced Technologies developed the transparent Aeroscreen. The design, which is similar to a small fairing, did not receive much interest from the FIA. In 2019 the Aeroscreen was adapted to use the halo as a structural frame for use in IndyCar. After the drivers had expressed their opposition to the introduction of the halo system, the FIA developed Shield, a transparent polyvinyl chloride screen. Sebastian Vettel was the first and only driver to try Shield in a Formula 1 car. During the free practice for the 2017 British Grand Prix, he completed a lap with the new system before ending the test early, complaining of distorted and blurred vision.
The system aroused some criticism before it was involved in any incidents, including that of Niki Lauda, who claimed that the system distorted the "essence of racing cars". The system was also initially unpopular with fans, with some saying that it was visually unappealing, against the concept of open-cockpit racing, and obstructed the driver's vision. At the 2018 Formula 2 race in Spain, Tadasuke Makino's halo was landed on by fellow Japanese driver Nirei Fukuzumi's car. In the 2018 Belgian Grand Prix, Charles Leclerc's halo was struck by Fernando Alonso's airborne McLaren. At the 2020 Bahrain Grand Prix, Romain Grosjean crashed into the barriers head-on, and the halo deflected the upper section of the barrier. At the 2021 Italian Grand Prix, Max Verstappen's wheel landed on the halo protecting Lewis Hamilton's head. At the 2022 British Grand Prix, Zhou Guanyu credited the halo with saving his life after his Alfa Romeo flipped and careered over the tyre barrier. During the 2022 Seoul ePrix, Nyck de Vries credited the halo after a multi-car collision. At the 2023 Baku Formula 2 round, Jehan Daruvala said the halo protected him during a safety restart. At the 2023 Indianapolis 500, Felix Rosenqvist spun out, and Kyle Kirkwood’s car impacted the wall, with the Aeroscreen protecting Kirkwood. During the 2025 Formula 2 sprint race at Austria's Red Bull Ring, the halo protected Luke Browning during a crash.