A Marl LED is to be fitted to all Formula One cars, following its approval by the sport governing body, FIA, It provides the warning light in a mandatory Crash Severity Indication System, which signals the severity of an accident to medical rescue crews.
The light shows race marshals attending an accident that a driver has been exposed to potentially damaging levels of shock, as determined by accelerometers placed around the car. If these forces exceed a specified level, the indicator light illuminates, and the driver is subjected to a compulsory medical examination.
The Marl LED specified operates at the 5V dc voltage of Formula One vehicle electrical equipment. It is a blue lamp, featuring a smoked lens to give the maximum on-off contrast. The LED has been brightness enhanced and is fully potted and sealed to protect it against the cleaning chemicals used, as well as spillages of fuel and other substances.
According to the regulations, the warning light is connected to the data logger and faces upwards. It must be recessed into the top of the survival cell no more than 150mm from the car centre line and the front of the cockpit opening and as near to the marshal neutral switch as is practical.