Which class of airspace covers operations that are hazardous to nonparticipating aircraft?

Restricted areas are designated for operations that may be hazardous to nonparticipating aircraft. These areas are established to limit air traffic due to the presence of activities that could pose a danger, such as military exercises, live-fire training, or other operations that involve potentially hazardous materials or actions.

Access to these areas is strictly controlled, and air traffic may be limited or prohibited altogether unless a specific clearance is obtained. This ensures the safety of both those engaging in the restricted activities and other aircraft in the vicinity.

While alert areas, warning areas, and prohibited areas also have implications for aircraft operations, they function differently. Alert areas are meant to notify pilots of activities that may be hazardous, but they do not impose restrictions. Warning areas are similar but are located over water and focus on notifying pilots of potential hazards without direct prohibitive measures. Prohibited areas are areas where flight is completely forbidden, but they are typically reserved for more sensitive operations, such as national security concerns, rather than just hazardous activities. Restricted areas specifically indicate that operations within them may be hazardous, making them the most fitting choice in this context.