What is the maximum allowable brake temperature prior to taxi?

The maximum allowable brake temperature prior to taxiing on the Dassault Falcon 7X is critical because maintaining the brakes within a safe temperature range ensures optimal performance and safety during the operation of the aircraft.

Selecting a brake temperature below 123°C and decreasing indicates that the brakes are cooling down, which is essential before initiating taxi. High temperatures can affect the performance and integrity of the brake system, potentially leading to brake failure or reduced efficiency during the takeoff and landing phases.

It is important to ensure that the brakes are not only below the threshold of 123°C but also that they are decreasing in temperature. This scenario demonstrates that the brakes are in a good condition to be utilized safely, as opposed to a stable or increasing temperature which could suggest potential issues or risk of overheating.

The other options mention stable or increasing temperatures, which would not be acceptable as they could lead to unsafe brake conditions during taxi and subsequent operations. A temperature that is stable at 123°C means it's at the maximum threshold, not a safe operating condition. Similarly, an increasing temperature indicates that the brakes might be heating up further, which is not advisable prior to taxi.