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Air Traffic Services -- User Group Process for the Design of Class B and C Airspace

User Group Process for the Design of Class B and C Airspace


Welcome to the airspace user group process for designing Class B and Class C airspace. User input is the key to successful airspace design and this guide has been prepared based on extensive experience with airspace user groups. AOPA has been an active participant in the user group process since its inception in the mid-1980s. The user group process has resulted in the successful implementation of Class B and C airspace at numerous locations around the country.

Although guidance for Class B and Class C airspace user groups has been provided since the late 1980s, issues have surfaced which dictated the need to update and reissue current guidance. This updated guide has been developed primarily for new user groups as well as those that have been inactive for several years and are now faced with proposals for new or modified Class B or C airspace. The guide provides detailed information for developing recommendations to the Federal Aviation Administration (FAA) for implementing those classes of airspace.

For the purposes of this guide, an airspace user group is defined as an informal, ad hoc entity of representatives of aviation interests. It is not a Federal advisory committee chartered under the Federal Advisory Committee Act, such as the national Aviation Rulemaking Advisory Committee. It is normally composed of representatives from the airlines, commuter operators, corporate operators, general aviation, fixed base operators, flight schools, State government aviation officials, and airport operators. The most effective user groups have been formed under the auspices of a State aviation department through cooperation from the National Association of State Aviation Officials. However, any association, business, or individual with an interest in the FAA's airspace proposal may initiate the formation of a user group.

Once a group has been organized, it may want to address other airspace and procedural enhancements. In some complex airspace locations there are permanent airspace user groups that handle continuing regulatory and non-regulatory airspace and procedural matters, including Class B and C airspace. These groups are very experienced in working with the FAA and have effected many beneficial airspace enhancements.

The user group process provides a meaningful dialogue among all users of the system prior to the issuance of a Notice of Proposed Rulemaking (NPRM). By achieving consensus among the users, the resultant recommendations address the interests of all classes of users much more than the generic FAA Class B or Class C design. This process is much more effective than one where individual aviation organizations separately seek changes with the FAA.

The FAA supports the user group process; however, the agency is legally constrained from being the organizer of an entity of this type. More information on the FAA's role is provided in the section on FAA participation.

One thought should always prevail with all users of the National Airspace System: the FAA doesn't own the airspace; it manages the airspace for the users. This finite resource needs to accommodate all users while allowing the FAA to perform its responsibility of providing air traffic control service to participating aircraft.


The user group process began in 1986 with the redesign of the Los Angeles, California terminal area airspace. The FAA offered the local airspace users the opportunity to participate in the redesign of the airspace around Los Angeles with the recognition that a better design would be the result. Not long after the user group process was started in Los Angeles, another group was organized to redesign the airspace around San Diego.

The next significant user group effort was the development of a new Class B airspace for Phoenix, Arizona. Using the Arizona Airspace Utilization Committee as the user group, a 'straw man proposal' or working design for the Class B was presented as a starting point. The group developed a recommended design that was significantly different from the FAA proposal and was accepted by the FAA with minor changes. The result was a Class B airspace design that worked for all users.

The Class B and Class C airspace user group design process works well and has been used at numerous locations around the country. AOPA has been represented on every user group. In 1992, AOPA wrote the FAA Administrator expressing our support for this process and encouraged the FAA to continue its support. The FAA responded, stating its commitment and support. ( FAA's Letter of Support for User Group Process)


The FAA's rulemaking process for establishing airspace is described in FAA Order 7400.2, Procedures for Handling Airspace Matters. In addition to the procedures for rulemaking, the order provides the establishment criteria and the guidelines for designing Class B and Class C airspace. It also includes guidelines for obtaining airspace user group input. Order 7400.2G, Paragraph 15-1-1

Informal Airspace Meetings

When the FAA is considering a location for Class B or Class C airspace, it sends out a notice that one or more informal airspace meetings will be held to inform the users of the planned airspace action. In addition to the information presented by the FAA, the meetings provide an opportunity for comments from the users. The notices are also published in the Federal Register and written comments are accepted from persons who cannot attend the meetings. Order 7400.2G. Paragraph 2-6-1

The informal airspace meetings and review of comments must be completed before the FAA may issue a NPRM. After reviewing the input from the meetings and written comments, the FAA will decide whether to proceed with a NPRM, explore an alternate course of action, or take no action.


If the FAA proceeds with Class B or Class C rulemaking, the next step is the issuance of a NPRM. This step provides another opportunity for users to submit written comments on the proposal; if the FAA believes there is a need for additional fact-finding, it may hold public meetings on the proposal, usually during the comment period.

Final Action

After analysis of all comments to the NPRM, the FAA will decide whether to issue a final rule that establishes the airspace, or withdraw the proposal. The final rule may differ from the NPRM as a result of the public comments.

Contacts with Outside Parties during Rulemaking

The FAA has a strict policy in Order 7400.2 regarding communication related to a particular rulemaking procedure between its employees and persons outside the agency. This policy is designed to ensure that the decision making process is open and fair during the rulemaking process. Order 7400.2G, Chapter 2


As stated in the introduction to this guide, a State aviation department has sponsored the most effective user groups. However, in some cases a State aviation office may not be able to undertake the task and a user association, airport authority, or other aviation organization should sponsor the group.

Group Membership

The group should be composed of members that represent a cross section of airspace users in the area that would be affected by the Class B or Class C airspace. For example, the sponsor should send invitations to AOPA, ALPA, ATA, EAA, HAI, and NBAA. ( Attachment A) In addition to these organizations, the Balloon Federation of America, United States Parachute Association, and the Soaring Society of America, Inc., should be included if their operations would be affected by the airspace proposal. There should also be representatives from military units, fixed base operators, airports, and flight schools affected by the proposal. Membership on the user group and attendance by nonmembers at meetings should be by invitation only.

The size of the group should be limited to no more that 20 members. There should be only one spokesperson from each organization. To ensure continuity during the process, it is essential that each member organization commit to having the same spokesperson participate on the group for as long as possible.

Getting Started

At the first meeting, the group should select a chairperson. It is recommended that the chairperson be a local representative who is familiar with the area. The chairperson should then designate someone to take notes at each meeting and provide a summary to the members before the next meeting.

Meetings should be scheduled at least three weeks apart. This allows ample time for reproduction, distribution, and examination of graphics, meeting summaries, agendas, etc. There should not be stringent limitations on the frequency and duration of the meetings. FAA headquarters in Washington, D.C., is committed to the user group process and has assured AOPA that sufficient time will be allowed for the user group to develop a recommended airspace design.

To enhance their understanding of local air traffic control (ATC) operations and the purpose of the airspace change, members of the group should make at least one visit to the Terminal Radar Approach Control to observe the operation. Also, group members whose operations would be affected significantly by the proposed airspace should invite controllers on flights in the local area to demonstrate the adverse impact.


It is very important that the group reach consensus on its recommended airspace design and every effort should be made to achieve this goal. A failure to reach consensus will weaken the group's effectiveness in getting the FAA to accept a design that accommodates all classes of users. Consensus is agreement by all members that the group's recommendation is acceptable. It is not a voting process; i.e., it does not mean that the majority rules.

Full consensus means that agreement among members is unanimous. All members agree fully in context and principle and all fully support the group's recommended airspace design.

General consensus means that, although there may be disagreement among the members of the group, the group has heard, recognized, acknowledged, and reconciled the concerns or objections to the general acceptability of the group. While not every member fully agrees, all members support the overall position of the group and agree not to object to the group's recommended airspace design.

If full or general consensus cannot be achieved, the chairperson should request each dissenting member to present his or her non-concurrence to the group in writing. Those comments are then attached to the group's recommendations.

FAA Participation

Local FAA ATC specialists should be invited to meetings to serve as technical experts and provide information on operations and ATC procedures. However, the FAA may not officially serve as a member of the user group. The FAA is prohibited from participating in the consensus process by statutory and policy requirements imposed on Federal agencies. Although it may appear desirable to have the FAA specialists as full participants in the group's activities, there are several reasons why they may not and should not offer recommendations or participate in the consensus process.

First, to have FAA personnel as members of the ad hoc user group could be interpreted as "regulation by negotiation," a process that must be conducted under the provisions of a chartered Advisory Committee as prescribed in Title 5 of the United States Code. Second, such participation would be "ex parte" activity that is prohibited by the Administrative Procedure Act and FAA and DOT policies.

The chairperson should ensure the number of FAA specialists attending the meetings is limited. Reports have been received that the FAA attendance sometimes is too large and unduly influences the group's discussions. The group should also consider inviting the FAA to attend only those meetings where it is necessary to obtain information that only the FAA can provide. Even though the FAA specialists are usually willing and eager to help develop an airspace design, their interests will be focused on efficiency of the ATC system. At some group meetings, FAA personnel suggested that the group should not develop an airspace design but provide only information on how the proposal will impact local and transient operations. Consequently, their well-intentioned efforts may deter the group from developing a recommendation that it sincerely believes will be best for all users.

After the user group develops a recommended design, it is reviewed by the local ATC facility and then forwarded to the FAA Regional Office with comments on the feasibility of the recommendation. If the local facility or the region cannot adopt the recommendation, it is incumbent upon them to come back to the user group with justifiable rationale. FAA headquarters does not expect any user group recommendation to be modified by the facility or the region, unless there are valid safety, regulatory, capacity or procedural issues that would dictate the change.

Public Meetings

After the FAA regional action has been reviewed and accepted by FAA Headquarters, it is issued as an NPRM. This provides another opportunity for the user group to provide comments on the FAA's proposed design. In some cases, the FAA may hold public meetings when it believes it needs more than written comments to make a fully informed decision. A designated member of the user group should make a presentation at these meetings in support of the group's recommendation. All comments are considered, and a final rule is issued unless there are reasons for withdrawing the proposal.

When the FAA issues a NPRM, the user group should consider holding its own 'public meetings' after submitting its recommendation to the FAA and before the NPRM comment period closes. Such meetings can be effective in gaining additional support from the local aviation community for the group's recommendation.


The FAA's standards for Class B and C airspace design are in Order 7400.2. Order 7400.2G, Chapters 15 & 16 The general design configuration for Class B is three concentric circles with radii of 10, 20, and 30 nautical miles (NM) from the primary airport and a vertical limit of 10,000 feet mean sea level (MSL). For Class C airspace, the general configuration is two concentric circles with radii of 5 and 10 NM from the primary airport, and a vertical limit of 4000 feet above the airport elevation.

As user groups participated in Class B and C airspace design over the years, they found that significant variations from the standard configurations resulted in better use of the airspace for all users. The following information describes the most common variations.

Top of the Class B

In determining the vertical limit of Class B airspace, it is important to consider the performance limitations of aircraft that typically fly VFR. Accordingly, the vertical limits should allow VFR operations at the lowest possible altitude above the Class B airspace. The vertical limit, however, should not be higher than 10,000 feet mean sea level (MSL). It is desirable to have the top of the Class B airspace at 8,000 feet MSL to allow VFR operations to transit above the airspace at altitudes within the performance capabilities of many general aviation aircraft.

Since 1989, the FAA has imposed equipment requirements that provide a safer environment for aircraft flying above Class B airspace. Current FAA regulations require all aircraft, with a few exceptions, to be equipped with altitude reporting transponders, commonly referred to as Mode C or Mode S, when operating within 30 nautical miles of the primary airport of a Class B area. The transponders transmit the positions and altitudes of these aircraft to the air traffic controllers' radar displays. In addition, commercial operators governed by FARs 121 and 135 are required to be equipped with the Traffic Alert and Collision Avoidance System (TCAS). The TCAS equipped aircraft are alerted to the positions and altitudes of the other aircraft equipped with Mode C and Mode S. The TCAS information, combined with traffic advisories from ATC, greatly reduces the potential for a mid air, or a near mid air, collision with a VFR aircraft that is not in communication with ATC in the airspace above the Class B.

VFR Transition Routes; VFR Corridors

There may be reasons why it could be difficult to design a Class B airspace with a ceiling below 10,000 feet MSL. The Los Angeles and San Diego, CA "mega" Class B airspace areas are examples where, in addition to a heavy volume of arriving and departing traffic, there is a high volume of IFR overflight traffic. However, even in such locations, it may be possible to use either VFR corridors or transition routes for VFR operations, instead of forcing those flights to circumnavigate the Class B area.

Establishing VFR waypoints in strategic locations around terminal airspace also gives pilots additional tools for navigating through these corridors or routes. VFR waypoints can be used to help pilots remain outside of the Class B and Class C airspace when flying underneath the floors and/or around the boundaries.

IFR Transition routes

IFR transition routes through Class B airspace for general aviation aircraft flying through the airspace en route to distant destinations are highly desirable. Since general aviation aircraft cruise at altitudes below the ceiling of most Class B airspace areas, access to that airspace for en route transition reduces cost and time, and is helpful to pilots in their flight planning. Establishing RNAV fixes could facilitate the implementation of IFR transition routes, although every effort should be made to design routes that can be flown with RNAV or VOR equipment. IFR transition routes are beneficial even if access is not available at certain times because of arriving or departing traffic saturation at the primary airport. For these locations, information can be published to advise pilots when IFR transition access is not available.

Floor of the Class B

The floor of the Class B should be designed to enclose IFR approaches and departures of all published procedures at the primary airport. FAA Handbook, "Procedures for Handling Airspace Matters" ( 7400.2) states that the "floor of the area between 10 and 20 NM shall be predicated on a 300-foot per NM gradient for 10NM." ( See graphic.) This criterion is based on heavy, older jet aircraft performance on a hot day. Most of these aircraft are being phased out or upgraded due to noise problems and obsolescence. The newer aircraft have a much higher climb performance capability and Class B floors might be designed to accommodate climb gradients in the range of 500 to 1000 feet per NM.

The user group should try to determine the climb gradients that are normally achieved by most large turbine powered aircraft that operate to and from the primary airport and review the published departure procedures. The heights of the Class B floors should be based on that information instead of a standard of 300 feet per NM.

If only one or two of the lower performing aircraft operate at the primary airport, then special ATC procedures could be implemented instead of lowering the floor of the Class B beyond 10 NM. Even if there are many of these type aircraft operating at the proposed location, these criteria should be revisited on a yearly basis. It is entirely possible that the floor of Class B could be raised when the situation warrants it.

There have been attempts to add a 500-foot buffer to the floor of a Class B beneath the minimum altitude of an instrument procedure or the altitudes used by ATC for vectoring. There is no requirement for a 500-foot buffer beneath the minimum altitude of an instrument approach or minimum vectoring altitude. While the concept of establishing such buffers appears advantageous, it would eliminate airspace necessary to allow non-participating VFR aircraft to operate under the Class B at prescribed VFR altitudes.

The user group should be alert for situations where VFR traffic could be dangerously compressed beneath the shelves of the Class B or Class C airspace. Examples of dangerous compression situations are: obstructions beneath the shelves; traffic congestion on frequently-used VFR routes and low level military training routes; and traffic at airports underlying the shelves.

Navigation Aids for Airspace Design

The FAA originally determined that Class B and C airspace should be designed in a circular configuration. To delineate the lateral boundaries it was logical then to use distance from a VORTAC, VOR/DME or an ILS/DME on the primary airport. Another means for delineation was the installation of a DME on an existing ILS at the primary airport.

Few aircraft used primarily for VFR have DME equipment and still use geographical landmarks when possible to identify the lateral boundaries of the airspace. When there are insufficient VFR landmarks to identify the boundaries, it is important that the circles be measured from the center of the primary airport. For locations that do not have a VORTAC located at the primary airport, the user group should recommend that a VORTAC in the vicinity be relocated to the geographic center of the airport prior to the implementation of the airspace.

If there is a justifiable reason that precludes the use of a navigational aid at the primary airport to identify the lateral boundaries, then geographical coordinates will allow the use of Loran C or GPS to identify the boundaries.

The user group should help the VFR pilot identify the boundaries by examining all options and combinations. This can include RNAV fixes, VFR waypoints, geographical landmarks, buildings, stadiums, major roads, dams, bodies of water, etc.

Stabilized Descents and Vectors

In the basic design of Class B or C airspace, the user group should examine all of the Standard Terminal Arrival Procedures (STAR) for the primary airport. Most aircraft would like to proceed directly to the runway using a three- degree stabilized descent gradient. However, the use of a stabilized descent for every STAR is often impractical because of the need for traffic separation, vectoring, etc. Still, the goal should be the application of stabilized descents in the initial design. After the initial design is developed, descent gradients can be adjusted, with information provided by local ATC specialists, to meet operational requirements. The group's recommendation should indicate the minimum amount of airspace that is needed for vectoring.


Class B and C airspace is depicted on Sectional charts and Terminal Area Charts. These charts depict the horizontal and vertical boundaries for VFR users who want to avoid the airspace. Since VFR pilots often use visual clues to determine their positions, it is very important to use prominent landmarks in the identification of boundaries whenever possible. Major highways, rivers, lakes, power plants, stadiums and other prominent landmarks can be used for airspace design AND for charting on visual charts. It is important to remember that transient VFR pilots need these visual clues even more than the local VFR pilots who are familiar with the area.

Class B and C airspace outlines are depicted on the low altitude instrument navigation (IFR) charts; however, these charts are not suitable for visual navigation and avoidance of the airspace. Class B and C airspace is depicted on the IFR charts simply for general information, since aircraft flying IFR are normally cleared into, or through, the airspace by ATC. For IFR operations this airspace is transparent to the user, but this is not true for the VFR user. This is the primary reason for using visual landmarks to delineate the boundaries whenever possible.


The user group final report and recommendations to the FAA may be organized in a format commonly used for such reports; i.e., an Executive Summary or Introduction, Background, Recommendations, and Appendices.

It is important to explain in the report whether or not a full or general consensus was achieved. If consensus was not achieved, the written dissenting view(s) should be appended to the report.

The report should include a graphic of the user group's recommended airspace configuration and a textual description. If needed, AOPA Air Traffic Services can provide information on methods for describing airspace.


This guide was prepared to assist airspace user groups in developing recommendations to FAA Class B and Class C airspace proposals so that the results will address the concerns of all users. The suggested guidelines for airspace modifications should not be viewed as the only methods for accommodating users' interests. Each location presents different challenges and may require more creative approaches.

The information on the FAA's airspace rulemaking process and links to Order 7400.2 will help to prevent misunderstanding about the FAA's role and responsibilities in working with informal user groups. Additional information is contained in FAA Order 7210.3W, Facility Operation and Administration: Class B Airspace, Paragraph 11-1-5; Charted VFR Flyway Planning Chart Program, Paragraph 11-5-1; Terminal VFR Route Program, Paragraph 11-7-1; and VFR Waypoint Program, Paragraph 11-10-1. Order 7210.3 Chapter 11

Airspace user groups can be very effective in working with the FAA to implement airspace changes that support safety objectives but do not impose unreasonable restrictions on any category of user.

Attachment A: List of Associations

Aircraft Owners and Pilots Association
421 Aviation Way
Frederick, MD 21701
1-800-USA-AOPA /

Air Line Pilots Association
535 Herndon Parkway
Post Office Box 1169
Herndon, VA 20172
703-689-2270 /

Air Transport Association of America, Incorporated
1301 Pennsylvania Avenue, Suite 1100
Washington, DC 20006
202-626-4000 /

Experimental Aircraft Association
EAA Aviation Center
3000 Poberezny Road
Oshkosh, WI 54902
920-426-4800 /

Helicopter Association International
1635 Prince Street
Alexandria, VA 22314
703-683-4646 /

National Association of State Aviation Officials
8401 Colesville Road, Suite 505
Silver Spring, MD 20910-3349
301-588-0587 /

National Business Aircraft Association, Incorporated
1200 18 th Street N.W.
Suite 400
Washington, DC 20036-2506
202-783-9000 /

National Association of Flight Instructors
EAA Aviation Center
P.O. Box 3086
Oshkosh, WI 54903-3086
920-426-6801 /

Balloon Federation of America
Post Office Box 400
Indianola, IA 50125
515-961-8809 /

United States Parachute Association
1440 Duke Street
Alexandria, VA 22314
703-836-3495 /

Soaring Society of America, Incorporated
Post Office Box 2100
Hobbs, New Mexico 88241-2100
505-392-1177 /

Attachment B: User Group Checklist

Attachment C: Airspace and Operations Analysis Checklist

Additional Attachments