When is it permissible to land or take off near an open-air assembly of more than 1000 persons?

The correct answer indicates that landing or taking off near an open-air assembly of more than 1000 persons is permissible only with procedures that have been notified by the Civil Aviation Authority (CAA). This reflects the regulations intended to ensure safety in crowded environments. The presence of a large assembly increases the risks associated with flight operations due to potential distractions, the possibility of injury to individuals on the ground, and the operational challenges that may arise.

Following established procedures minimizes these risks by providing guidelines on how to safely conduct flights in proximity to large crowds. These procedures are designed to account for factors such as the type of aircraft, weather conditions, and the nature of the event.

Other options may seem plausible but fall short of the regulatory requirements in place. For instance, taking off or landing at a private airfield or with permission from an organizer doesn't inherently guarantee safety or adherence to the law. Similarly, conducting such operations only during daylight hours, while it could reduce risk, does not address the overarching need for approved procedures from the CAA when interacting with large public gatherings.