AIM Text
Alert areas are depicted on aeronautical charts to inform nonparticipating pilots of areas that may contain a high volume of pilot training or an unusual type of aerial activity. Pilots should be particularly alert when flying in these areas. All activity within an alert area must be conducted in accordance with CFRs, without waiver, and pilots of participating aircraft as well as pilots transiting the area must be equally responsible for collision avoidance.
Source: FAA Aeronautical Information Manual · current edition · paragraph 3-4-6.
The short answer
This AIM section is FAA advisory guidance explaining Alert Areas, which are charted to inform nonparticipating pilots of areas with a high volume of pilot training or unusual aerial activity. The surrounding text also covers Controlled Firing Areas (CFAs) and National Security Areas (NSAs), the latter linked to 14 CFR 99.7.
Research Notes
Common Questions
Can I fly through an Alert Area without permission?
Why aren’t Controlled Firing Areas charted?
Per the AIM, CFA activities are suspended immediately when spotter aircraft, radar, or ground lookouts indicate an aircraft might be approaching. Because they do not cause a nonparticipating aircraft to change its flight path, there is no need to chart CFAs.
What should I do about a National Security Area?
The AIM requests pilots voluntarily avoid flying through a depicted NSA. When greater security is needed, flight may be temporarily prohibited by regulation under 14 CFR 99.7, with prohibitions issued by System Operations Security and disseminated via NOTAM.