What are the four components that make up total stopping distance for a commercial motor vehicle with air brakes?

AAMVA CDL Manual, Section 5, subsection 5.4.4 (Stopping Distance), pp. 5-8 to 5-9, Figure 5.6

Every one of these four phases eats up real distance while the truck is still moving at or near full speed, and drivers who only think about 'braking distance' dramatically underestimate how much space they actually need to stop. Knowing all four components is what the exam, and real following-distance judgment, is built on.