What equipment aids in the loading and off-loading of loose passenger baggage at commercial aircraft?

The mobile baggage conveyor is designed specifically to assist in the efficient loading and unloading of loose passenger baggage at commercial aircraft. This equipment typically features a belt system that can extend and retract, allowing ground crew to easily transfer bags from the terminal to the airplane's cargo hold and vice versa. The conveyor eliminates the physical strain involved in manually lifting luggage, thereby increasing speed and safety during ground operations.

While other equipment, such as the aircraft loader, also plays a role in baggage handling, it primarily functions to transport cargo containers or pallets rather than loose baggage. The truck-mounted staircase and passenger stair truck are essential for enabling passenger access to and from the aircraft, but they do not contribute directly to the handling of baggage. Hence, the mobile baggage conveyor is the most appropriate choice for the task specified in the question.