MONTE CARLO, Monaco -- It's rare to see the black flag waved in a Formula One race these days -- even more so to see one during a practice session.
But that's what happened in the early stages of the opening session for the Monaco Grand Prix on Thursday, when they were issued for Haas drivers Kevin Magnussen and Romain Grosjean. The black flag is the most serious that can be waved at a driver -- it demands a driver returns immediately to the pit-lane ahead of what is usually disqualification.
Haas later confirmed it had asked for the flags to be waved at their drivers as they were unable to communicate, having lost all telemetry and radio on the pit-wall.