What is the correct braking technique for descending a long, steep downgrade?

49 CFR 383.111(b)(7)(i) (Proper braking techniques); AAMVA CDL Manual, Section 5, subsection 5.4.6 (Proper Braking Technique), p. 5-9

This apply-hold-release cycle is the specific, testable technique CDL exams expect you to know, and it is also what actually prevents runaway-truck situations on real mountain grades. Getting into low gear before you start down is the step most new drivers skip, and it is the one that matters most.