Stopping distance for a vehicle with air brakes is the sum of:
Correct. Air-brake stopping distance is perception + reaction + brake lag + braking — the brake lag is the unique addition.
CDL Practice Question #129
Category: Air Brakes
Why this question matters
This question is one of 71 in our Air Brakes bank. The reasoning above comes directly from the AAMVA CDL Manual, the source document used by every U.S. state DMV. Memorizing the underlying rule — not just the letter answer — is what separates passing on the first attempt from a return trip and another fee.