What is the correct braking technique for controlling speed on a long, steep downgrade in a vehicle with air brakes?

Explanation

The correct technique on a long, steep downgrade is to first select the proper low gear, then press the brakes hard enough that the rig clearly slows down, let off once speed drops to about 5 mph below the safe speed, and press again once speed climbs back up to the safe speed, repeating this pattern for the length of the grade. 49 CFR 383.111(b)(7)(i) directly requires CDL applicants to know proper braking techniques as part of general operating practices, a direct match for this snub-braking method; the specific 5 mph margin and timing come from the manual, not the CFR paragraph itself. Riding the brake pedal continuously is wrong because sustained light braking generates continuous heat, which is exactly what causes brake fade on a long grade. Braking only once at the bottom is wrong because by then the vehicle has already built up dangerous speed with no engine braking assistance used along the way. Using the parking brake control on a moving vehicle is wrong and dangerous; the parking brake is not designed for graduated speed control while underway.

Source: 49 CFR 383.111(b)(7)(i)