Racing flags are traditionally used in auto racing and similar motorsports to communicate important messages to drivers. Typically, the primary flagman, sometimes the grand marshal of a race, waves the flags atop a flagstand near the start/finish line. On most circuits, several officials are also stationed at strategically chosen positions along the course in order to communicate to drivers who cannot see the flagstand. This is especially common at road courses, which usually feature several sharp turns and relatively steep hills. Alternatively, some racecourses employ flashing lights to supplement the primary flag at the start/finish line.
|Start/Restart of Race||Start/Restart of Race||End of Hazard/Restart|
|Caution||Local Caution (single) or Full-Course Caution (twin)||Local Caution or Full-Course Caution (if displayed with "SC" sign)|
|Debris (road courses only)||Oil/Slippery Course||Debris/Oil/Slippery Course|
|Pit Road Closed||Pit Road Closed||not used|
|Final Lap||Final Lap||Slow vehicle on Track|
|not used||Ambulance on Course||not used except for Pickup Truck and SCSA oval races: Final Lap similar to NASCAR white flag|
|Penalty of some form||Penalty of some form||Instant Disqualification for a driver|
|not used||not used||Car has a problem and needs to stop|
|not used||not used||Unsportsman-like Conduct|
|No Longer Scored||No Longer Scored||not used|
| Local Caution/ |
Slow Vehicle on Track (Road courses only)
|not used||Faster Car Approaching|
|Faster Car Approaching||Faster Car Approaching||not used|
|End of Race|
It is also crucial to note that some flags can be replaced by lights for better visibility (in rain, fog, crucial blind corners, ...) or during the night.
Also in NASCAR, when a green and yellow flag wave at the same time, this indicates that the race is under caution, but that the race has started and laps are being counted. Such usually takes place to finish drying a track after a start delayed by rain.
When shown at a marshalling post, a green flag may indicate the end of a local yellow-flag zone.
IndyCar has incorporated a stylized lowercase 'e' into its green flag to promote the series' use of ethanol as a motor fuel.
Before the use of starting lights in Formula One and most other FIA sanctioned or associated events, the national flag of the country in which a race is occurring, instead of a green flag, was used to signal its start, and still does on occasion in the event of equipment failure.
In Formula One racing, a yellow flag displayed at the starter's stand or a marshal station indicates that there is a hazard downstream of the station. The manner of display depends on the location of the hazard:
When shown at a station, drivers are prohibited from passing until either the hazard or the next flag station displaying a green flag (signifying the end of a cautionary section) is passed. This flag is shown at the discretion of the marshals manning the station.
A double stationary flag, or a yellow flag accompanied by a “SC” sign denotes a full-course yellow, requiring the use of a safety car. This indicates that all racing on the circuit must cease and drivers must slow down, hold position and follow any safety cars that have been dispatched. Passing other cars is strictly prohibited, unless not passing would create a safety hazard.
In NASCAR and IndyCar series, a single yellow flag waved from the starter's stand places the race under caution. At this time a pace car will enter the course and lead the field at a safe predetermined speed. At these races, yellow flashing lights are usually used to supplement the primary flag at the start/finish line. The field is locked into place at the beginning of a caution period and no one is allowed to pass another car without mutual consent (excluding crashed and immobile cars). In some races, though, cars may pass one another on the pit road during a caution period.
In some series (Indy Racing League, Champ Car, and beginning in 2007, Formula One) lapped cars between the pace car and the leader will be allowed to move to the rear of the next lap when the signal is given two laps before a restart.
In Formula One, all lapped cars between the leaders are permitted to advance one lap.
The rule, as enforced in the three open-wheel series, is designed to prevent lapped cars from blocking on ensuing restarts, as to prevent unsportsmanlike blocking when a lapped teammate or friend of one driver attempts to help that driver through impeding the progress of an opponent on the restart.
There are several hazards that might cause a need to delay or prematurely end a race. Many hazards, such as rain, darkness, a blocked course (due to debris, water or safety vehicles), a car on fire, or a devastating multi-car crash (especially one that results in serious injuries or one that results in damage to walls, fences or the surface itself which require repairs) might prompt series officials to call for the red flag.
Some series use a red flag when a severe accident has occurred or to temporarily stop a race nearing the end of a race. This is usually done when a collision requiring cleanup would otherwise extend the caution period to take longer than the amount of race laps available to finish the race, when a fuel spill occurs on the circuit, or to maximise safety team work. During such a red-flag period, cars are directed to stop in line at a specific point on the track, usually directly opposite to the incident.
Also, a red flag or board, sometimes with a yellow saltire, at the entrance to the pits can indicate that the pits are closed. Such a flag is used in both the IndyCar and NASCAR series. In NASCAR, a red flag with a black flag signals the end of a practice session.
In the event of a bad start, the yellow and red flags may be displayed together to indicate a restart. Drivers will go back to their starting positions and line up for another start. This is rarely used, and can create much confusion as the drivers attempt to get back in order.
In all championships which use the FIA International Sporting Code, the white flag indicates the presence of an official car in the circuit when displayed at a marshaling post.
In the IRL and NASCAR, a white flag displayed from the starter's tower indicates the start of the last lap for all the competitors.
The white flag can also be used for the FIA purpose in North America. In the IRL, this white flag includes a red cross whose arms extend all the way to the edges of the flag. Usually, official cars are not used in those circuits, but instead a pickup truck or tow truck will be used because it is easier to distinguish an official truck from a racing car. However, in NASCAR, the blue flag is instead used for this purpose.
Other administrators do not distinguish mechanical problems or unsportsmanlike conduct from rules violations.
In NASCAR events, a single checkered flag is waved to signal the completion of a race. In IndyCar and F1, 2 checkered flags are waved together.
NASCAR traditionally has a special version of the checkered flag sewn for Victory Lane that has the name and date of the race on it. That flag is used for the team in winner's photographs taken after the race, and is a prize awarded to the team along with the race trophy. Teams often hang such flags at race team's headquarters in a similar fashion to other sports hanging championship banners from the rafters at stadiums.
Another origin theory claim is that the checkered flag's earliest known use was for 19th century bicycle races in France.
A more likely explanation is that a single-colored flag would be less conspicuous against the background of a crowd, especially when early races were run on dirt tracks (and therefore dust reduced the driver's visibility).
The earliest known photographic record of a checkered flag being used to end a race was from Long Island, New York in 1904 at the inaugural Vanderbilt Cup race. Some historians dispute the dating of this photograph, and attribute it to the Vanderbilt races of 1906 or 1908.
A 2006 publication "The Origin of the Checker Flag - A Search for Racing's Holy Grail", written by historian Fred Egloff and published by the International Motor Racing Research Center at Watkins Glen, traces the flag's origin to one Sidney Waldon, an employee of the Packard Motor Car Company, who in 1906 devised the flag to mark "checking stations" (now called "checkpoints") along the rally-style events of the Glidden Tour.
In 1980, USAC starter Duane Sweeney started a tradition at the Indianapolis 500 by waving twin checkered flags at the end of the race. Previous starters had only used a single flag. Sweeney also marked the first use of twin green flags at the start of the race.
The Polish Victory Lap and "doughnuts" burnout have become popular as post-race tributes to honor fallen or injured race car drivers such as Alan Kulwicki (killed in a 1993 plane crash) and Alex Zanardi (lost both legs in a 2001 Champ Car race).
In contrast to smaller circuits, road racing drivers rely heavily on the use of flags. As it is impractical to have spotters covering all segments of a winding road course, the first indication to drivers of local hazards almost always comes from marshals stationed at various flagstations around the course. Missing or disregarding a flag can have critical consequences - as Mario and Michael Andretti discovered during a 1991 CART race in Detroit, Michigan. Michael came around a blind corner at high speed, without heeding the yellow flag being displayed - and plowed into the back of a CART safety truck tending to another disabled car. Fifteen seconds later, his father Mario disregarded the same madly waving yellows and crashed into Michael.