What requirement must cargo meet if it is carried anywhere in the passenger compartment of a commuter air carrier airplane?

The requirement that cargo must not restrict access to aisles between crew and passengers is crucial for maintaining safety and facilitating emergencies on board an aircraft. When cargo is carried in the passenger compartment, it is essential that it does not impede movement within the cabin. This allows crew members to access all areas of the passenger compartment quickly and ensures that passengers can evacuate the aircraft promptly in the case of an emergency.

By keeping aisles clear, this regulation helps to maintain a safer environment, allowing crew members to perform their duties effectively without obstructions. It also ensures that all exits remain accessible, which is vital during emergency situations where every second counts.

While labeling, temperature control, and designated storage compartments can be important under certain conditions, the fundamental priority in an aircraft is the clear passage for safety. This is why the specific requirement regarding aisle access is the most pertinent when considering cargo carried in the passenger compartment.