Explained: Why so many F1 drivers were penalised for pitlane speeding in Monaco

The FIA has found no irregularities in its measurement system and believes the wave of penalties is linked to drivers slightly cutting the pitlane entry. Teams were warned about this by race control before the start

The Monaco Grand Prix produced a series of penalties for speeding in the pitlane. The FIA documents released after the race reveal that in every case the infringement was less than one kilometre per hour. For Oscar Piastri, George Russell, Franco Colapinto and Pierre Gasly, the excess was just 0.1 km/h.

After the eventful race in the principality, the FIA reviewed its own timing lines and measurement equipment and found no abnormalities. Instead, the governing body believes the issue is related to the line drivers chose when entering the pitlane.

In Monaco, the pit entry can be cut slightly. There is a kink at the entrance to the pitlane where drivers can effectively continue straight on the right-hand side for a short distance, gaining a few metres.

According to an FIA spokesperson, the measurement begins the moment the first wheel of the car enters the fast lane. In the case of cutting the entry, that would be the front-left wheel.

Because the system measures average speed through the pitlane using electronic timing loops embedded in the track surface and the car's official FIA transponder, all of the infringements ended up being extremely small. Over all pitlane sectors, the effect is averaged out to less than one kilometre per hour.

Lewis Hamilton, who still finished second despite receiving a five-second time penalty, supported that theory and believes the chosen line was also the cause of his own penalty.

Lewis Hamilton, Ferrari

Photo by: Sam Bagnall / Sutton Images via Getty Images

“Yeah, I wasn't speeding. I think it's just the way the pitlane is. I've done this pitlane for years. It's not like I came in and didn't press the button or something like that. Pitlane limiter is on immediately,” Hamilton said in the post-race press conference.

“I think it's just the line that you take, which is the same line we've all taken for years where you come in, you kind of cut part of the white line, head down, went out. And I was shocked to hear that I was speeding because I wasn't actually above the speed.

“I think it's the distance and something that we really need to look into because I heard lots of people got that today and they probably weren't really speeding.”

Race control highlighted the risk before the race

The FIA has stated that race control warned teams about this potential pitfall before the race, both in terms of the speed and the actual pitlane distance that is measured, and advised drivers to take the wider entry line.

One notable detail is that, apart from Hamilton, all of the penalised drivers were using Mercedes power units. However, that has nothing to do with the power unit itself or the calibration of the pitlane limiter.

McLaren team principal Andrea Stella acknowledged that, in Piastri’s case as well, the issue appears to be linked to the line taken into the pitlane.

Oscar Piastri, McLaren

Photo by: Anni Graf - Formula 1 via Getty Images

“We think it might come from shortcutting too much. I think that's the hypothesis at the moment, so then we told Oscar to just avoid that,” Stella said.

“But initially it wasn't understood. We know that sometimes when you shortcut too much this may induce you to be measured in excess of the speed limiter. But we don't know more at the moment.”

Alpine has requested a right of review over the matter, as Pierre Gasly believes he has been "robbed" of a Monaco GP podium.