Per the Large Truck Crash Causation Study (LTCCS) cited in the CDL manual, what percentage of large-truck crashes involved the commercial driver being externally distracted?

AAMVA CDL Manual (nhcdm.pdf) Section 2.9.1, p. 2-21 (LTCCS distraction statistics). Note: distracted driving is not one of the 20 enumerated knowledge topics listed in 49 CFR 383.111(a)(1)-(20), so no single CFR paragraph specifically governs this content

These numbers show that distraction is a real, measurable contributor to large-truck crashes, not just anecdotal advice. Knowing that external distractions (something outside the cab) are a bigger factor than internal ones can help a driver prioritize scanning the road over, say, glancing at a dashboard screen.