Under what condition must each occupant of an aircraft wear an approved parachute?

The requirement for each occupant of an aircraft to wear an approved parachute is specifically tied to maneuvering conditions where significant changes in pitch can result in increased risk for passengers, especially during aerobatic maneuvers. When the aircraft is intentionally pitched up or down by 30 degrees or more, the dynamics and forces acting on the aircraft can become extreme. This situation can increase the likelihood of needing to evacuate the aircraft quickly due to a potential loss of control or other emergencies that may arise during such maneuvers.

Therefore, the answer highlights crucial safety regulations that aim to ensure that occupants are equipped to respond to heightened risk, particularly in circumstances where rapid action may be necessary. In contrast, the other conditions listed, such as during takeoff and landing, above 10,000 feet, or flying over congested areas, do not inherently require parachute use for all occupants, nor do they represent the same level of immediate risk that could necessitate such a safety measure.