The most important thing to do on a downgrade is:

On a downgrade, the most crucial action is to control the bus speed through proper use of the transmission and brakes. When descending a hill or incline, gravity will naturally increase the speed of the vehicle. It's essential to manage this acceleration effectively to prevent the bus from gaining too much speed, which could lead to loss of control.

Using the transmission to select a lower gear helps to slow the vehicle down using engine braking, which reduces wear on the foot brakes. This method is particularly important in larger vehicles like buses, as they can be heavier and more challenging to stop. Additionally, appropriately applying the brakes at intervals can prevent them from overheating, which could lead to brake failure.

The focus here is on maintaining a safe and manageable speed, ensuring the safety of both the passengers and others on the road.