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Proceed With Caution - Where NOT to Go

A Review of Special Use Airspace

Source:, By James Williams

Years ago I was having a discussion with a pilot who’d recently decided to trade his long serving airplane for a boat. He said, “You know, one advantage of the airplane was the FAA can’t board you.” While this is still true, the world has changed since that conversation in that the government can, and will, intercept you. That tends to lead to unpleasant conversations in small rooms with federal agents which, all doctors agree, isn’t particularly good for your health. In an effort to help you avoid such disagreeably close encounters, we offer this article on the kinds of Special Use Airspace (SUA) you may find during your flights.

Do Not Pass Go

The first and most restrictive form of SUA is the prohibited area. As the name suggests, this is airspace where all flight is prohibited within its boundaries, from the surface to the prescribed altitude. These areas are usually associated with national security and do not have an effective time. They can, at times, be surrounded by TFRs as well. Luckily these most restrictive areas are relatively rare. That said, the serious nature of any encounter with their boundaries provides a strong incentive to note and avoid them by a safe margin — not the 0.0001 nautical mile “miss” made possible by GPS. Prohibited areas are noted on charts with a “P” and a two or three digit number, e.g., P-40 — the Camp David presidential retreat, in a cyan box, circle, or other shape.

Coordination Required

Next we move on to restricted areas. Again, the name implies the meaning. Prohibited areas prohibit flight. Restricted areas constrain, but do not completely outlaw operation within the boundaries. Another key difference is that a restricted area may not go all the way down to the surface. While prohibited areas are defined by a need to protect something on the surface, restricted areas in many cases are more about airspace. Also, restricted areas are only restricted when they are “active” in terms of the reason for the restricted use. That means that a pilot may pass through this airspace at times outside of that “active” window. The best way to ensure that you are transiting during the inactive time is to contact the controlling ATC facility or operate on an IFR flight plan. Restricted areas are a good bit more common than their prohibited cousins. They are labeled on the charts with an “R” and a number, usually three or four digits, and possibly a letter. An example would include R-2515 which covers airspace around Edwards Air Force Base, home to extensive flight testing by the government and private industry.

The twin sibling of the restricted area is the warning area. While the two are nearly identical in terms of depiction and description, a warning area differs in that it extends beyond the three-mile boundary of U.S. airspace. Since the FAA can’t technically restrict airspace outside the country, the agency has established warning areas to identify airspace that pilots should avoid without contacting the controlling ATC facility. Warning areas also differ in that you are not actually restricted from the airspace under threat of enforcement action but rather warned that the activities within could be hazardous to non-participating aircraft. Both warning and restricted areas are depicted on the charts as cyan boxes.

Management is Not Responsible for Lost Aircraft

Next we come to Military Operations Areas (MOA). These are areas where the military can practice activities that may require more space than the restricted area will allow. What makes the MOA different from a restricted area, though, is that IFR pilots may be cleared through an active MOA if separation can be provided by ATC. Also, MOAs aren’t technically restricted — which means that that VFR pilots may enter one even if it is active. Much like a Flight Service briefer will tell you VFR is “not recommended” during bad weather, entering an active MOA is likewise “not recommended.” MOAs usually have a name, like Bull Dog or Avon Park, and are depicted on charts as magenta boxes.

Heads Up

Another type of area that should concern pilots is the alert area. These are areas of increased flight training or other unusual aeronautical activity. Alert areas are designed to keep transient traffic away from pilots doing air work or other operations that might not fit neatly with through traffic. Alert areas don’t have a controlling ATC facility, so you don’t have to ask permission to enter or transit the alert area. It’s charted only so you can be aware of it and not be surprised by the airplane that could be maneuvering in an unpredictable way. Florida has several alert areas due to the close proximity of many flight schools. Alert areas are depicted on the charts with a magenta box and an “A” followed by numbers and possibly a letter.

Nothing to See Here

The last area we need to look at is a national security area. These are areas where pilots are requested not to fly through below a certain altitude. Unlike the mandatory nature of prohibited or restricted areas, a national security area simply shows airspace that pilots are requested to avoid. This could be a military installation or a nuclear plant. Something that would not require a prohibited area, but that the FAA or other agencies would prefer pilots to avoid. They are depicted by dashed heavy magenta lines and a text box with an explanation. A word of caution: these areas may be subject to a temporary flight restriction (TFR). That TFR would be issued by NOTAM.

All Together Now

Another thing to be aware of is that some of these special use airspace types can overlap. For instance, you could encounter a restricted area that sits on top of a prohibited area. Just because you flew over the prohibited area doesn’t mean you’re free and clear. You may also see restricted areas and MOAs that overlap or abut.

To avoid problems while navigating around these more complicated airspace scenarios, it’s always a good idea to contact Flight Service or ATC before entering the vicinity of SUA. Operating under IFR is another good way to help keep you in the clear. If you are not instrument rated, consider asking ATC for flight following.

In conclusion, there are three basic strategies to avoid an unpleasant run in with SUA. First, know the types of SUA around your route of flight and what the requirements of each are. Second, get a good briefing so you know what’s active and what’s not. Finally, stay in contact with ATC when possible. This will help you avoid last minute SUA and TFR issues.

For more information:

FAA’s Enhanced SUA Website -

James Williams is FAA Safety Briefing’s associate editor and photo editor. He is also a pilot and ground instructor.

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