General Tips  | Plan ahead — When it comes to airspace, change is the only constant. It's essential to plan your route carefully, using up-to-date charts and paying attention to airspace altitudes, active times, and communications frequencies. If the route takes you into or near Class B airspace, get a terminal area chart: It shows details that aren't on the sectional. | | Get a briefing — There's no substitute for a briefing from Flight Service or DUATs. If you call Flight Service, specifically request information on temporary flight restrictions (TFRs), since they aren't depicted on charts. Graphical TFRs are available on the . | | Just in case —Remember to monitor the emergency frequency (121.5) when able. It's also wise to be familiar with intercept procedures: ASF provides a handy . | "Basic" Airspace | Class B — Think "big." Class B airspace surrounds certain large, busy airports — Los Angeles, Boston, Atlanta, etc. Each Class B area is broken down into multiple segments, each with its own floor and ceiling altitudes. VFR aircraft need a specific clearance to enter Class B airspace, so don't wait until the last second to call approach control. Also remember that Mode C transponders are required within 30 nautical miles of the primary airport, and that (if allowed) solo student pilot operations are subject to restrictions. | | Class C — Established around moderately busy airports, Class C areas are usually 20 nautical miles in diameter. Though a specific clearance isn't necessary, pilots are required to establish and maintain two-way communication with ATC prior to entry, and aircraft must be equipped with Mode C transponders, even if simply overflying the airspace. | | Class D — Class D airspace surrounds other, less busy towered airports. As with Class C, two-way communication with ATC serves as permission to enter. That communication will usually be with a control tower, since most Class D airports don't have approach control facilities. Some Class D towers operate on a part-time basis: When they close, the airspace reverts to a Class E surface area and the tower frequency (usually) becomes the common traffic advisory frequency (CTAF). | | TRSA — Terminal Radar Service Areas surround certain Class D airports. Depicted by gray lines on sectional charts, TRSAs are holdovers from the old (pre-1993) airspace classification system, and offer expanded ATC radar services. For practical purposes, operating in a TRSA is a lot like operating in Class C airspace-the difference being that pilots aren't required to participate in TRSAs (though ASF recommends doing so). If you choose not to participate, remember that the requirements for the Class D airspace within the TRSA still apply. | | Class E — Unless otherwise designated, the airspace between 1,200 AGL and 18,000 MSL is Class E-the least restrictive controlled airspace. Around most nontowered fields, Class E airspace extends downward to 700 AGL, though at some airports it goes all the way to the surface. If you decide to do pattern work in marginal VFR conditions, remember that you could be sharing the airspace with IFR traffic, which may not see you as it emerges from the clouds during descent. | | Class G — Any airspace that's "left over" is considered Class G, or uncontrolled. These days, pilots usually encounter it only below 700 AGL around nontowered fields, or below 1,200 AGL elsewhere. Visibility and ceiling requirements for VFR in Class G are minimal (one statute mile and clear of clouds), but remember: Legal doesn't equal safe. | | Special Use and Other Airspace | MOA — MOAs (Military Operations Areas) provide space for military training flights. VFR aircraft are allowed to operate in active MOAs, but that doesn't make it a good idea to plow on through. Contrary to what many pilots believe, military aircraft might not see you on radar in time to avoid a collision. Call the controlling ATC facility (shown on sectional charts) for MOA status prior to entry. For more information on sharing the skies with military aircraft, take ASF's free online course. | | Restricted areas — Restricted areas exist to keep aircraft away from hazardous military activities-artillery shelling, for example. It's legal to fly through a "cold" (inactive) restricted area, but you should always contact the controlling agency (listed on the sectional chart) to verify that status before entering it. Don't rely on the published hours of operation. | | Prohibited areas — Typically established for reasons of national security, prohibited areas are outlined in blue on sectional charts. It's never legal to enter a prohibited area, so steer well clear. | | Alert areas — Advisory in nature, alert areas are established in places where pilots are likely to encounter a great deal of flight training or other aerial activity. There are no special requirements, but it's a good idea to be extra vigilant in scanning for traffic. | | ADIZ — The contiguous ADIZ surrounds the nation's borders. Aircraft operating in it must be on either an IFR or defense VFR (DVFR) flight plan, have a discrete transponder code, and be in communication with ATC. The same basic rules apply to the land-based ADIZ (Washington, D.C., is the only current example), but there are some important differences. For more information, see AOPA's information on . | |
