The Blue Flag

The blue flag is shown to a driver who is about to be lapped — that is, caught by the race leaders who are a full lap ahead. It tells them to let the faster car through at the first safe opportunity.

Back-markers are expected not to interfere with the cars fighting for position at the front. Ignore the blue flags — typically three in a row — and the lapped driver risks a penalty for holding up the leaders. The signal is shown both by the marshals and on the dashboard, so there is no excuse for missing it.

Blue flags appear in practice and qualifying too, but they mean something slightly different there: a driver cruising on a slow lap must yield to anyone on a flying lap. Impeding a rival’s qualifying lap — even unintentionally, by being in the way through a fast corner — regularly earns a grid penalty, so drivers and engineers watch the mirrors and the radio constantly to avoid blocking.