In which type of aircraft is the dual rail system permanently installed?

The dual rail system is a critical component in aircraft designed to facilitate the safe and efficient movement of cargo. The correct choice relates to the design and operational requirements of aircraft within the Air Mobility Command (AMC), which includes all cargo capable aircraft. These aircraft are engineered to support extensive logistical operations, thus necessitating more robust systems for loading and unloading cargo in varied environments.

The dual rail system is permanently installed in these cargo-capable aircraft to enhance stability and security when transporting heavy and oversized loads. This system allows for greater flexibility and efficiency during cargo operations, making it an essential feature for the types of missions carried out by AMC aircraft.

In contrast, small transport aircraft may not be equipped with a dual rail system, as their design does not usually require the same level of cargo handling capability as larger cargo aircraft. Fighter jets, primarily focused on combat missions rather than cargo transportation, also do not include this system as part of their design. The KC-135 aircraft, while a refueling and transport aircraft, is specifically mentioned in a limited context and does not represent the broader category of all cargo-capable aircraft within AMC where the dual rail system is standardized across the fleet.