by Tom Hamilton
The current airspace designations came into effect
on September 16, 1993 when US pilots said good-bye to ARSAs, TCAs, and all
of those other fun-loving aviation acronyms. In their place the designations
of A, B, C, D, E and G. The intent was to make airspace "easier for
pilots to understand."
According to the FAA there were four reasons for the change:
*to simplify airspace designations,
*to increase standardization of equipment and pilot requirements for operations in various classes of airspace,
*to promote pilot understanding of air traffic control services available, and
* to achieve international commonalty and satisfy our responsibilities as a member state of ICAO.
A quick review of the airspace designator follows. For more detail, see Airspace Reclassification Summary chart. For a complete review and understanding of the airspace classification system read the Aeronautical Information Manual:
Class A Airspace: All operations must be conducted under instrument flight rules (IFR) and are subject to ATC clearances and instructions. ATC separation is provided to all aircraft. Generally, that airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska.
Class B Airspace: Generally, that airspace from the surface to 10,000 feet MSL surrounding the nation's busiest airports in terms of IFR operations or passenger enplanements. The configuration of each Class B airspace area is individually tailored and consists of a surface area and two or more layers. Operations may be conducted under IFR, special visual flight rules (SVFR), or VFR. However, all aircraft are subject to ATC clearances and instructions. ATC separation is provided to all aircraft.
Class C Airspace: Generally, that airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower, are service by a radar approach control, and that have a certain number of IFR operations or passenger enplanements. Although the configuration of each Class C airspace area is individually tailored, the airspace usually consists of a five nautical miles radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a ten nautical mile radius shelf area that extends from 1,200 feet to 4,000 feet above the airport elevation. Operations may be conducted under IFR, VFR, or special VFR; However. all aircraft are subject to ATC clearances and instructions. ATC separation is provided to all aircraft operating under IFR or SVFR and, as necessary, to any aircraft operating VFR when any aircraft operating IFR is involved. All VFR operations will be provided with safety alerts and, upon request, conflict resolution instructions.
Class D Airspace: Generally, that airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored and when instrument procedure are published, the airspace will normally be designed to contain the procedures. Operations may be conducted under IFR, SVFR or VFR; however, all aircraft are subject to ATC clearances and instructions. ATC separation is provided to aircraft operating under IFR or SVFR only. All traffic will receive safety alerts and, on pilot request, conflict resolution instructions.
Class E Airspace: Generally, if the airspace is not Class A, B, C, or D, and it is controlled airspace, it is Class E airspace. Operations may be conducted under IFR, SVFR or VFR. ATC separation is provided only to aircraft operating under IFR and SVFR within a surface area. As far as practical, ATC may provide safety alerts to aircraft operating under VFR
Class G Airspace: Uncontrolled airspace is that portion of that has not been designated as Class A, B, C, D, and E airspace. Operations can be conducted under IFR or VFR. ATC separation is not provided.
There are additional categories of airspace that we, as balloonists, are seldom bothered with, that category of airspace is known as "special use.". These areas include Alert Areas, Controlled Firing Areas, Intensive Student Jet Training Areas, Military Operations Areas, Prohibited Areas, Restricted Areas and Warning Areas. For a review of the characteristics of these areas, see Special Use Airspace on the next page.
