Montreal, 10 June 2018. At the Canadian Grand Prix the model Winnie Harlow, guest of honour, waves the chequered flag as Sebastian Vettel is completing the sixty-ninth of the seventy scheduled laps, with one still to go. A communication error, FIA race director Charlie Whiting would later say. The regulations, however, leave no room for interpretation: if the chequered flag comes out early, the result is taken from the previous lap. So that Grand Prix ends, on paper, at lap 68.

What came next is even more telling, and not for the folklore. For 2019 the FIA decided that the official end-of-race signal would be the chequered light panel, with the flag reduced to a symbolic gesture. In October, at Suzuka, it was the panel system that got it wrong: it lit up a lap early and the result was frozen at lap 52 of 53. From 2020 the physical flag went back to being the signal that ends the race. Two rule changes in little more than a year, for a piece of cloth.

It is easy to think of F1 flags as a side show, almost a tradition to be preserved. I read them differently: they are the highway code of a circuit. A handful of signals, each with a precise obligation, which twenty-two drivers have to read, even at more than three hundred kilometres an hour, without stopping to ask. They are defined by the FIA in Appendix H of the International Sporting Code, and Formula 1 applies them within its own sporting regulations.

Who shows the flags in F1

The flags come from two different places, and the difference matters. Along the track there are the marshal posts, which handle the danger and traffic signals: yellow, yellow with red stripes, blue, white and green. Then there are race control’s signals, normally shown on the start line: those that stop or end a session and those aimed at a single driver, namely red, chequered, black, black with an orange disc, and black and white. Red is a case apart: only race control can call it, but when it comes out it is shown together on the line and at every marshal post around the track.

For years now, LED light panels have stood alongside the flags, repeating the same signals around the track with the same meaning. The flags waved by the marshals have not gone away, though: Appendix H states that marshals are still needed whenever several signals have to be shown at the same time.

Yellow flag and double yellow

Yellow is the danger signal, and the one you see most often. A single waved flag says three things: slow down, do not overtake, be prepared to change direction. There is a hazard beside or partly on the track, and the driver must show that he braked earlier, or at least noticeably reduced speed, in that sector.

The double yellow, two flags waved together, raises the stakes: slow down significantly, do not overtake, be prepared to change direction or stop. The hazard wholly or partly blocks the track, or marshals are at work. In practice and qualifying the consequences are serious: under double yellows a driver must show that he has abandoned the fast lap, and in qualifying, sprint qualifying included, the Formula 1 regulations delete the time of any lap in which he passes through the double-yellow sector. With single or double yellows alike, the ban on overtaking runs from the first flag to the green flag shown after the incident.

Green flag

Green says the track is clear. It is waved at the marshal post immediately after the incident that required the yellow, and from there drivers can race and overtake again. Race control can also use it to start a practice session, and Appendix H allows a marshal at the back of the grid to use it, at the end of the formation lap, to signal to the starter that the cars in his field of vision are stationary.

Red flag

Only race control can decide on the red flag, when a session or the race has to be stopped: a serious accident, barriers to repair, rain that is too heavy. At that moment it is shown together on the start line and at every marshal post. The cars slow down and return to the pit lane, where the teams may carry out only the work the regulations allow, including changing tyres and repairing damage, while waiting for the restart. The clock is unforgiving: a lap time recorded after the red flag is first displayed is deleted, in practice, in qualifying and in the race.

For those watching from outside, a red flag is a pause. In the race, for those on the pit wall, it is a second start: tyres can be changed without losing time in the pit lane, and the gaps built up on track disappear at the restart. Strategies, which we cover in our article on Formula 1 strategy, are rewritten in a matter of minutes.

Blue flag

Blue is about traffic. In practice it warns that a faster car is coming. In the race it is shown to a driver about to be lapped, who must let the car behind through at the first opportunity. In Formula 1, as a matter of race control practice, the team of the driver about to be lapped gets an early warning when the faster car closes to around three seconds, and the blue panels light up when the gap drops below 1.2 seconds. Ignoring blue flags costs you: the stewards’ usual sanction is a five-second penalty, generally with two penalty points on the super licence.

White flag

White is perhaps the most misunderstood. It has nothing to do with the safety car, which has its own board marked SC (we cover it in our article on the F1 safety car): it signals that there is a much slower vehicle in the sector controlled by that post, such as a recovery vehicle or a service car.

Yellow flag with red stripes

This is the grip flag. It is shown motionless, not waved, to warn that beyond that point grip deteriorates because of oil or water on the track. Depending on the circumstances it stays out for at least four laps, unless the surface returns to normal sooner, and no green flag is needed afterwards.

The flags with a number: black, black with orange disc, black and white

Three flags are aimed at a single driver, and they come with a black board showing his car number.

Black is the most serious: the driver must return to his pit, or to the place set out in the regulations, the next time he approaches the pit entry, and his race is over. Only the stewards can decide to show it. Estoril, 1989: Nigel Mansell, penalised for reversing in the pit lane, does not stop, collides with Ayrton Senna while fighting for second place, is excluded from the race and misses the next Grand Prix.

The black flag with an orange disc, which the paddock calls the meatball, signals a mechanical problem that may endanger the driver or others: the car must come into the pits and can rejoin only once the chief scrutineer is satisfied that the fault has been fixed. In 2022 Kevin Magnussen was shown it three times, in Canada, Hungary and Singapore, each time for a damaged front wing, and after the controversy the FIA indicated it would use it more sparingly.

The black and white flag, divided diagonally, is a warning: it is shown once only, for unsporting behaviour or for an action that may lead to a penalty if repeated. In races it is often seen for track limits: the third offence brings the black and white flag, the fourth a five-second penalty. The other sanctions, from the drive-through to grid drops, are set out in our article on F1 penalties.

Chequered flag

The chequered flag marks the end of a practice session or of the race. It is waved until every car has crossed the finish line. After Montreal and Suzuka it is once again the signal that counts: if it comes out early it still stands, and the result is taken from the last lap completed before the signal. The start, on the other hand, is given in Formula 1 not by a flag but by the lights.

Flags through a sponsor’s eyes

In my view there is also a commercial reason to know them. Every flag changes the story of a race: a double yellow at the wrong moment wipes out a qualifying lap, a red reshuffles the strategy, a black and white flag makes as much news as an overtake. A brand that experiences Formula 1 only as a space on the livery is at the mercy of these moments. One that has built a content and hospitality plan knows how to tell them, in the paddock and on its own channels, while they are happening.

The same goes for hospitality. Anyone coming to a Grand Prix for the first time is better off having them explained before the start: once you understand a lap under yellow flags, you watch the race differently, and that is when a Formula 1 weekend stops being an expensive ticket and becomes an experience worth telling. What a brand actually buys when it enters this sport is covered on our page about Formula 1 sponsorship.

A flag waved one lap early shortened a Grand Prix by two laps. In Formula 1 the signals do not accompany the race. They decide it.