15.10 Red flag: Immediately cease racing and proceed slowly and with maximum caution to start line or pits as instructed by marshal' s, being prepared to stop should the track be blocked. No Overtaking.

15.11 Red flag waved at individual marshal' s posts. The Race has been stopped. Proceed as 15.10 above. No Overtaking.

In practical terms, the red flag starts at the start/finish line, and goes around in both directions. As a flagger if you have a visual of another red flag at any post (try and ensure it's not a red umberella, or a red jacket etc.) from either side, then put out the red flag. It is crucial to get this flag out as quickly as possible, but it is also important to note that if a red flag goes out it stays out. Never hold out the red flag, and withdraw it again, especially if even one driver has seen it. It is also important not to get caught up in the radio messages... you may hear "RED FLAG, RED FLAG" urgently being shouted over the radio, but until you get a visual of it at a flag post, don't put it out.

If there is an incident at your post when red flags go out, it is imperative that the flagger does not drop the yellow flag to put out the red one. If the yellow and a change of surface have to be held out for example, you may be able to hang the red-flag out of the fence, but if worst comes to the worst, the drivers will see the red flag at the next post. If they miss the yellow flag a serious incident, could become substantially worse.