Black and White Diagonal Flag

The Black and White Diagonal Flag is a warning flag in motorsport that officials show to a driver, along with their car number, to alert them that they've been reported for unsportsmanlike behavior on the track.

This distinctive flag features a diagonal split design, with black filling the upper portion and white filling the lower portion. When race officials display this flag at a marshal post or on the pit wall, they always show it alongside a board displaying the specific car number of the driver being warned. This ensures there's no confusion about who the warning is directed toward.

The flag serves as an official notice that a driver's conduct has crossed the line from hard racing into behavior that violates the sporting regulations. Think of it as a "yellow card" in soccer or football—it's a formal warning that says "we're watching you, and if you continue, there will be consequences." The key point is that the black and white diagonal flag itself is not a penalty. It's purely a warning shot.

So what kind of behavior triggers this warning? The most common reason is when a driver deliberately tries to force another car off the track in a way that goes beyond acceptable racing. While aggressive defending is part of motorsport, intentionally pushing a competitor onto the grass or into a wall crosses into unsportsmanlike territory. Another trigger is when drivers leave their cars during or immediately after a race to confront another driver physically, which is considered dangerous and unprofessional.

The flag can also be shown for repeatedly ignoring blue flags, which tell slower drivers to let faster cars pass, or for persistently exceeding track limits to gain an unfair advantage. Essentially, any behavior that shows disregard for the rules or the safety of other competitors can result in this warning.

The decision to show the black and white diagonal flag typically comes from senior race officials called the Clerk of the Course or the Stewards. These officials monitor the race closely and review incidents reported by other stewards around the track. Once they determine a driver's actions warrant a warning, they direct the marshals to display the flag.

Importantly, the flag is usually shown only once per incident. If the driver continues the problematic behavior after receiving the warning, officials will escalate to actual penalties. These penalties might include time penalties added to the driver's race time, drive-through penalties where the driver must enter the pit lane and drive through at reduced speed, or even disqualification in severe cases.

A notable example occurred during the 2019 Italian Grand Prix at Monza, when Ferrari driver Charles Leclerc received the black and white diagonal flag while defending his position against Mercedes driver Lewis Hamilton. Officials determined his defensive moves were too aggressive and warranted the warning, though he was not penalized and went on to win the race.