Alert areas must not extend into which type of airspace?

Alert areas are designated to inform pilots about a higher-than-normal potential for hazards, such as unusual aerial activity, and are intended to provide a warning rather than impose restrictions. Prohibited areas, on the other hand, are specifically established where flight is completely forbidden due to national security or safety concerns, such as activities involving sensitive government installations or military operations.

The nature of prohibited areas means that they are not compatible with the purpose of alert areas, which are aimed at enhancing safety by promoting awareness rather than restricting access. Thus, alert areas must not extend into prohibited areas to avoid conflicts between the safety information provided and the absolute restrictions that apply within those zones. This ensures that pilots can operate with clarity regarding where they are permitted to fly while still being made aware of any associated risks in surrounding airspace.