Planning ahead for a school bus evacuation includes assigning older student assistants to the emergency exits. Why can that assignment not be the whole plan?

Explanation

The plan cannot rest on those helpers because the bus may be carrying no older or dependable children at all on the day it matters, which is why the drill has to be explained to every child aboard. Any plan that assumes a particular sort of passenger is present collapses on the day that passenger is not, and a bus roster shifts from run to run, route to route, trip to trip. The assignments remain worth making, two steady older children to each exit, shown how to help the rest down, and one more to walk the group to the safe spot. But every child still needs to know how each exit actually works, and to know that what the driver says goes, because on the wrong day the only person aboard who knows the drill is the driver. The wrong options each invent a procedural restriction that does not exist, on what a helper may do, on which trips the arrangement covers, or on how long it lasts, and none is the real reason, which is simply that the children the plan names may not be there. 49 CFR 383.123(a)(2)(ii) makes procedures for safely evacuating passengers a required knowledge area without stating any procedure, so this is attributed to the manual.

Source: 49 CFR 383.123(a)(2)(ii)