Dust generation is highest when the stator and rotor components of the carbon brakes are cold, i.e. during the initial brake application while on the landing roll and taxi-out. Break wear and correspondingly dust-generation is therefore highest during those phases of operation.
From a friction point of view, in case of carbon brakes the higher the temperature, the better the friction coefficient/deceleration behaviour due to special tribological effects at temperatures exceeding 300°C. However, from a lifetime point of view, temperatures should be kept below 500°C since oxidation effects begin to degrade the structural integrity of the brakes on a long term.
Optimum brake temperatures from an operational point of view depend on the carbon brake pack (i.e. depending on brake manufacturer, e.g. messier-bugatti, Goodrich) in use on the corresponding aircraft.
Fuel, OTP and aircraft utility rate are key factors for most operators, i.e. aiming for the optimum turn-off more often requires firm and continuous brake application to reduce taxi-in time and safe fuel. Brakes consequently get hotter and need to be cooled to enable a 20 to 25 minute turnaround time.