What action should you perform before backing an ARFF apparatus into a restricted space?

Ensuring a clear line of sight is crucial before backing an ARFF apparatus into a restricted space because it allows the operator to have full visibility of the surroundings. This step is vital for preventing accidents and ensuring the safety of both personnel and equipment. A clear line of sight enables the driver to observe any obstacles or persons that may be in the immediate area, thus minimizing the risk of collisions and injuries.

Having visibility also aids in making informed decisions on whether it is safe to proceed with the maneuver. This consideration is especially important in tight spaces where visibility may be compromised. Other actions, such as honking the horn constantly or putting the vehicle in reverse immediately, do not directly enhance safety in the same way; those methods may not effectively communicate the vehicle's intentions to nearby personnel or allow for a thorough assessment of the area. Turning off the engine is unnecessary and may cause delays, as the driver needs to remain in a ready position to navigate the vehicle safely.