Red Bull finished fourth with Max Verstappen in Miami, before lodging a protest against third-placed finisher George Russell.

Verstappen lost track position to Russell due to the timing of a mid-race Virtual Safety Car which allowed Russell to pit and lose less time compared to the Dutch driver’s stop under normal race conditions.

Christian Horner explains protest against George Russell

Following his battle with the two McLaren drivers, Verstappen was circulating in third when he made his pitstop on Lap 26. Swapping from the medium to the hard tyre, he made his stop under normal race conditions.

Just a lap later, Haas’ Ollie Bearman pulled off the track following an apparent engine failure and Race Control opted to neutralise the drivers’ speed by issuing the Virtual Safety Car conditions which force all drivers to drive to a set delta time.

Russell, who was yet to stop, took the opportunity to dive into the pits for fresh tyres and, thanks to the beneficial timing of his stop as Verstappen couldn’t drive at full speed, came out ahead of the Dutch driver.

Verstappen kept the pressure on Russell but lacked a pace advantage to be able to attack the Mercedes driver but was able to hang on within a few seconds of the British driver.

Later in the race, Sauber’s Gabriel Bortoleto pulled off the road following a similar engine issue, with the VSC deployed once again.

With the drivers all slowing down, Verstappen radioed into his team to ask them to “check if George lifted, it was yellow”, referring to the yellow flag conditions in place.

Verstappen was later asked to try to stay within five seconds of Russell by the chequered flag, which he managed with ease as he came home 2.3 seconds behind the Mercedes. The request piqued Verstappen’s interest as he enquired as to why he needed to stay within five seconds, with no straight answer given by his race engineer GianPiero Lambiase at the time.

But, shortly after the chequered flag, it became obvious why as Red Bull lodged a protest against Russell on the basis of an alleged breach of Article 2.5.5.b of Appendix H of the International Sporting Code (ISC), pertaining to a failure to slow under yellow flags.

If Red Bull’s protest was successful, it would have resulted in a time penalty for Russell – explaining why the request was made of Verstappen to remain within the distance of the smallest time penalty possible.

Speaking to the media, including PlanetF1.com, team boss Christian Horner explained why Red Bull lodged the protest.

“We’re not purporting or suggesting that there’s anything illegal on the car – we felt that George Russell has done something that is in breach of the regs in the way that they’re written,” he said.

“So that’s why we put a protest in today because, more than anything, you want clarity, the regulations say there should be a reduction in speed.

“It doesn’t talk about a lift, it doesn’t talk about time off the top, it talks about a reduction in speed.

“We very clearly did that, and that was why Max flagged it immediately from what he saw in the cockpit.”

With the zone in question being under a single yellow flag, the ISC states that drivers should, “Reduce your speed, do not overtake, and be prepared to change direction.

“There is a hazard beside or partly on the track.

“It must be evident that a driver has reduced speed; this means a driver is expected to have braked earlier and/or noticeably reduced speed in that sector.”

A recent update to the FIA Sporting Regulations has been outlined in accordance with the requirements of the ISC, with Article 26.1.a stating that, “Any driver passing through a waved yellow flag marshalling sector must reduce their speed and be prepared to change direction.

“In order for the stewards to be satisfied that any such driver has complied with these requirements they are expected to have braked earlier and/or discernibly reduced speed in the relevant marshalling sector.”

Red Bull’s claim was that, while Russell had lifted off, he had not slowed down and, therefore, was not in compliance with the requirement to discernibly reduce speed.

What did the FIA stewards decide?

Red Bull headed to the hearing with their head of sporting regulations Stephen Knowles, as well as Lambiase, while Mercedes had Russell and sporting director Ron Meadows.

Red Bull’s argument was that the definition of a “discernible reduction in speed”, as required by the regulations, means passing the yellow flag zone at a speed lower than than upon entering the zone – which is what Verstappen had done, and allowed him to be able to tell Russell had pulled away in that section.

Mercedes’ defence was that the common practice – accepted by the teams and the FIA – is that a significant throttle lift in a yellow flag zone is considered appropriate, with Russell having done so and having done so to a greater extent than other cars in the race.

But a throttle lift is a particularly inexact method to establish whether a rule pertaining to speed has been adhered to, while also raising the question of what percentage throttle lift constitutes a ‘significant’ lift – if higher drag levels on one car mean a driver only has to lift off 10 per cent compared to what a driver of a more efficient car slows with a 20 per cent lift, for example, have both drivers satisfied the undefined lift requirement?

The stewards reviewed telemetry data and established Russell had lifted off by 25 per cent, with a 30 per cent torque reduction – but did this throttle lift actually correspond with a reduction in speed? Red Bull’s argument was contingent on this answer.

The wording of Article 26.1.a does not make it clear whether the requirement to “discernibly reduce speed” is a reduction in absolute speed or a reduction relative to regular racing speeds.

As Russell was proven considerably slower than his regular racing speed, even though his absolute speed actually increased through the yellow flag zone, the stewards ruled in favour of Russell and ejected Red Bull’s protest.

The determination reached by the stewards was that the reduction of speed in a yellow flag zone can “only relate to a reduction relative to the regular racing speed as the reduction of the absolute speed can, depending on the part of the track in which the yellow flag is displayed, represent a compliance or a non-compliance with the regulations, whereas a reduction of the relative speed always signals that the driver has acknowledged and respected the yellow flag.

“For instance, in a braking zone, the absolute speed can be reduced without necessarily complying with the regulations.”

While Red Bull’s protest wasn’t upheld, the stewards’ decision has determined a precedent for future scenarios like this, providing the teams with more detail of what’s expected in these scenarios than the long practice of simply carrying out a “significant throttle lift”.

As such, the teams now have something of a definition of understanding as to what a discernible reduction in speed actually entails – even if it is still something of an inexact science.

Long gone are the days when Mika Hakkinen’s infamous method of acknowledging yellow flags by simply sticking his hand in the air but continuing at unabated speed passed muster…

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