Which classification of terrain is described as vertical and highly dangerous, where injury and death are possible?

Class 5 terrain is characterized by its verticality and significant danger, making it a high-risk environment for personnel. In this classification, the environment typically includes steep cliffs, sheer walls, and other features that present serious hazards to movement and safety. Because of the vertical nature of the terrain, there is an increased likelihood of falls, rockslides, and limited escape routes, all contributing to a higher potential for injury or fatality. This classification emphasizes the need for advanced skills, specialized equipment, and thorough risk assessment when operating in such regions, highlighting why it is deemed highly dangerous compared to other classes of terrain.