What is a reason why professionals do not recommend the practice of fanning during long downhill runs?

Answer: C — The short breaks do not allow for brake cooling

The practice of fanning, which involves applying and releasing the brakes intermittently, is not recommended during long downhill runs primarily because the brief periods of brake application do not allow sufficient time for the brakes to cool. Braking generates heat, and during extended descents, the brakes can become overheated if they are continuously engaged. By fanning, drivers may keep their brakes engaged longer than necessary without providing adequate time for heat dissipation, which can lead to brake fade and ultimately compromise braking effectiveness, putting both the driver and others on the road at risk. Understanding the need for adequate cooling is crucial for maintaining the integrity and functionality of air brake systems, especially in scenarios where prolonged braking is required.