A Restricted Area on an aeronautical chart indicates airspace where:
Why →
Restricted Areas (designated "R" followed by a number) contain hazards such as artillery firing, aerial gunnery, or missile launches. They may be active part-time or full-time. When active, entry requires ATC authorization. When inactive, ATC can advise pilots they may operate at their own risk.The trap →
Prohibited Areas are the permanent no-fly zones. Restricted Areas can be entered when inactive or with authorization. The "at pilot's own risk" option applies only when the area is not active.SOURCE → 14 CFR § 73.17, FAA AIM Chapter 3CHECKED APR 21ACS II.A.K3EASY