Which factor is NOT a frequent contributing cause to mountaineering accidents?

The factor that is not a frequent contributing cause to mountaineering accidents is the use of protective gear. In fact, utilizing protective gear is a critical safety measure that significantly increases a climber's chances of safely navigating challenging terrains. Gear such as harnesses, helmets, and climbing aids are designed to prevent falls and reduce the severity of injuries should they occur.

The presence of protective gear allows climbers to explore more difficult routes with added confidence and safety. While it's possible for gear to fail or be improperly used, the act of using protective equipment itself is generally associated with promoting safety and mitigating risks, rather than contributing to accidents. Therefore, the correct answer highlights the importance of protective gear in mountaineering safety rather than viewing it as a risk factor.