Accidents involving flying wheels were the main impetus for work on cockpit protection and the key focus when testing both the halo and alternatives such as the shield.
Mekies explained that a wheel assembly hitting the cockpit at 225km/h (140mph) – “a speed we felt was a larger possibility" – was the key test that had to be passed.
But the FIA analyzed three different crash scenarios: car to car collisions, car to environment contact, and external factors, such as wheels and debris.
It looked at past accidents, mainly from F1 but also other categories, to see what difference the halo would have made.
Romain Grosjean’s Lotus landing on Fernando Alonso’s Ferrari in the 2012 Belgian GP startline crash was among the car-to-car incidents examined.
It also considered shunts where cars went under tyre barriers – such as Luciano Burti’s 2001 Belgian GP crash and Heikki Kovalainen’s ’08 Spanish GP accident – or rolled along barriers, as EJ Viso did in GP2 at Magny-Cours in ’07.
The study even included Pascal Wehrlein’s Monaco GP incident this year as new pictures from the FIA’s cockpit camera revealed how close his helmet was to the barrier was his Sauber was upturned.
“We played the ‘what if?’ scenario," says Mekies.
“We fitted the halo onto the car, and we simulated these accidents, and tried not only to simulate that very single accident scenario, but also around that scenario.
“We tried to look at 5cms above, 10cms above, 5cms to the right, 10cms to the right, and so on.
“At the end of that for each of these cases we then looked at if it was very positive, neutral, or negative.
“The number of scenarios in which the halo would have helped is overwhelming compared with the number of scenarios where it could have be neutral or negative."
All the cases detailed in the FIA presentation to the drivers and media were either positive, positive on balance, or neutral – with Jules Bianchi’s Suzuka 2014 crash among the few categorized as neutral. None came out as negative, although Mekies acknowledges that the FIA can never rule out such an outcome.
It also determined that the halo would have had a positive outcome in the cases of Henry Surtees and Justin Wilson’s fatal incidents.
The FIA also acknowledges that it can’t provide complete protection against smaller items of debris, such as the suspension spring that struck Felipe Massa in Hungarian GP qualifying in 2009.
But tests have shown that its presence significantly improves a driver’s chances even in these situations.
“We looked at mathematical studies whereby we played the game of throwing millions of small objects to the halo from all different angles, and all different positions," Mekies explains.
“Statistically when you put the structure in front of the driver you are going to increase his protection against small debris coming to hit him, compared to not having the halo."