McLaren team principal Andrea Stella has insisted that his team did not take excessive risks with its car setup at the Las Vegas Grand Prix despite both cars getting disqualified for excessive plank wear.
Lando Norris, who finished second before disqualification, and Oscar Piastri, who finished fourth, were both stripped of their points in Las Vegas, reigniting the title battle with Max Verstappen with two rounds left to run.
The rules around plank wear exist to stop teams running their cars at dangerously low ride heights in pursuit of performance, but Stella insists McLaren made a genuine error in Las Vegas due to the lack of dry-weather practice.
"Based on the data we had acquired in practice, we do not believe we took excessive risks in terms of ride height and we also added a safety margin for qualifying and the race, compared to practice, in terms of clearance to the ground," he said.
"However, the safety margin was negated by the unexpected onset of the large vertical oscillations, which caused the car to touch the ground.
"The porpoising condition that the car developed in the race was also a difficult one to mitigate, as even a reduction in speed -- an action that, in theory, should increase clearance to the ground -- was only effective in some parts of the track but in others was actually counterproductive."
Stella explained that the specific cause for the excessive wear was "unexpected occurrence of extensive porpoising."
Porpoising occurs when the underside of the car gets so close to the track surface that the airflow rushing underneath suddenly stalls and creates a momentary loss of downforce.
The car pops back up on its suspension, which in turn means the underfloor aerodynamics start working again and slams the car back down, resulting in contact between the plank assembly and the ground.
Once the porpoising motion starts, it continues until the driver slows enough to stop it.
Stella said the team tried to mitigate the problem during the race by telling its drivers to lift and coast at the end of straights when the aerodynamic load on the car is at its most extreme, but ultimately the problem persisted on both cars.
"From the early laps of the race, it was clear from the data that the level of unexpected porpoising would be a concern," Stella added.
"We were able to monitor the situation better on Lando's car using telemetry data, but it was made more difficult on Oscar's car, after we lost one of the sensors we use to establish the level of grounding.
"We realised relatively soon that this level of porpoising was causing a high level of skid wear energy and this is the reason why both drivers started to take remedial actions in various parts of the circuit. Unfortunately, we also saw that, because of the car operating window and the circuit characteristics, most of these actions were not effective enough in reducing porpoising."
Over the course of a grand prix, F1's technical regulations allow for 1mm of wear to the composite plank fitted to the underside of the car, with measurements taken at four holes that are protected by titanium skids.
In Las Vegas, Norris' car was found to be 0.12mm over the permitted wear amount at the most worn skid, while Piastri's was found to be illegal by 0.26mm. Although small, any margin of excessive wear is enough for a car to be disqualified.
"Unlike sporting or financial rules -- there is no proportionality in the application of penalties for technical regulation infringements," Stella said.
"The FIA itself has admitted that this lack of proportionality should be addressed in the future to ensure that minor and accidental technical infringements, with minimal or no performance benefits, do not lead to disproportionate consequences.
"It should also be remembered that the FIA itself emphasised that the infringement was not intentional, there was no deliberate attempt to circumvent the regulations, and there were also mitigating circumstances, as we explained to the event stewards."
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Norris goes into the final two rounds of the season with a 24-point lead over both his teammate Piastri and Red Bull's Verstappen, meaning he can secure the title this weekend in Qatar but it is possible for championship to go down to the final round in Abu Dhabi.
Stella is confident the issues the team faced in Las Vegas will not reoccur in Qatar and believes the lessons learned from the disqualifications will ensure the cars are legal at the end of this weekend's race.
"The conditions we experienced last weekend and which led to the onset of porpoising and excess of grounding, compared to what was expected, are very specific to the operating window of the car in Vegas and the circuit characteristics," he said.
"We have a well-established and consolidated way of setting up the car and we are confident that this will lead us to an optimal plan for the coming races, starting from the Lusail International Circuit," he said. "
"Nevertheless, we learn from every lesson and the one in Las Vegas has been able to provide some useful information about the operating window of the car and the porpoising regime.
"What happened in Vegas was due to an anomaly in the behaviour of the car, rather than it being the outcome of an excessive or unreasonable chase of performance.
"Our way of acting and thinking as a team, with a strong focus on performance, has brought us to where we are today, namely winning two consecutive constructors' titles and having two drivers at the top of the championship with two races to go.
"We, as a team, constantly learn from experience and we calibrate our approach all the time and we will certainly use any information gained through the situation experienced in Vegas."