During a school-bus-specific pre-trip inspection, what must a driver verify about the stop arm and safety arm (if equipped)?

49 CFR Part 380, Appendix D, Unit D1.9 (citing 49 CFR 392.7 and 396.11); AAMVA CDL Manual Section 11.3, School Bus Only

The stop arm and safety arm are the primary tools that warn other drivers a bus is stopped and keep children out of the most dangerous zones around the bus. A damaged or non-functioning stop arm means passing drivers won't know to stop, and a failed safety arm removes the barrier that forces kids to walk clear of the bus. Catching the problem during the pre-trip inspection, instead of mid-route, prevents a situation where children are exposed to passing traffic with no warning system working.