Class Alpha Airspace

Introduction:

Class Alpha Airspace Dimensions:

  • Class Alpha Airspace Depicted
    Amazon, Sectional Charts
  • Vertically, Class Alpha begins at 18,000' Mean Sea Level (MSL) up to and including FL600 (about 60,000' MSL).
  • Horizontally, Class Alpha begins when within 12 Nautical Miles (NM) of the coast in 48 contiguous states and Alaska and designated international airspace beyond 12 NM off the coast of the 48 contiguous States and Alaska within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic procedures apply.
    • Examples include Santa Barbara Island, Farallon Islands, and airspace south of latitude 25°04'00" North.
  • Class Alpha airspace does not include the airspace less than 1,500 feet above the earth's surface and the Alaska Peninsula west of longitude 160°00'00" West.
  • Class Alpha Airspace Depicted
    Class Alpha Airspace Depicted

Class Alpha Airspace Depiction:

  • Sectional Charts
    Amazon, Sectional Charts
  • Navigation charts omit Class A airspace depictions.
  • Sectional Charts
    Amazon, Sectional Charts

Class Alpha Operating Rules & Pilot/Equipment Requirements:

  • VFR Visibility Requirements:

    • Unless otherwise authorized, each person operating an aircraft in Class A airspace must conduct operations under Instrument Flight Rules (IFR).
      • See 14 Code of Federal Regulations (FAR) Section 71.33, Sections 91.167 through 91.193, Sections 91.215 through 91.217, and Sections 91.225 through 91.227.

  • Entry Requirements:

  • Equipment Requirements:

    • Transponder:

      • ADS-B Out Requirements
        ADS-B Out Requirements
      • Unless otherwise authorized by ATC, an operable radar beacon transponder with automatic altitude reporting capability and operable ADS−B Out equipment.
      • ADS-B Out Requirements
        ADS-B Out Requirements

    • Communication Equipment:

      • Two-way radio communications with the controlling agency (described below) are required.

  • Pilot Qualifications:

  • ATC Clearances & Separation

    • ATC Facility:

    • Separation standards are applied and provided for all aircraft.
    • Pilots must change their altimeter setting from the local altimeter to 29.92 when climbing through 18,000 feet.
      • Setting 29.92 ensures all aircraft flying in Class A airspace have the same altimeter setting and will have proper altitude separation.
    • Non-Reduced Vertical Separation Minima (RVSM) separation is 2,000' vertically.
    • RVSM separation is 1,000' vertically.

  • Jet & Q Routes:

    • Jet Routes and Q Routes
      High Altitude Enroute Chart

    • Jet Routes:

      • Within the cruise altitudes are Jet Routes, or "J" Routes, which are highways in the sky, much the same as Victor routes.
      • Jet Routes begin at 18,000' MSL and end at Flight Level (FL) 450 (about 45,000').
      • The letter "J" precedes a number to label the airway.
      • Note the range of Jet Routes is less than the dimensions of Class Alpha airspace. [Figure 2]
        • Limited due to Standard Service Volume (SSV) of ground stations.
      • Jet routes have no defined width.
      • A Navigational Aid (NAVAID) on a continuing jet route is NOT part of the segment and is not to be included in your flight plan.

    • Q Routes:

      • Q Routes are available for use by RNAV-equipped aircraft between 18,000' MSL and FL450 (about 45,000'), the same as J Routes.
      • Enroute High Altitude Charts depict Q Routes. [Figure 2]
        • Operations above FL450 (about 45,000') are permitted point-to-point.
      • Area navigation (RNAV) routes are established in low-altitude and high-altitude structures, depicted on the enroute low and high chart series.
      • High-altitude RNAV routes are identified with a "Q" prefix (except the Q-routes in the Gulf of Mexico), and low-altitude RNAV routes are identified with a "T" prefix.
      • RNAV routes and data are depicted in aeronautical blue.
      • In addition to the published routes, pilots may fly random RNAV routes under IFR if ATC approves.
      • Random RNAV routes are direct routes, based on RNAV capability, between waypoints defined in terms of latitude/longitude coordinates, degree-distance fixes, or offsets from established routes/airways at a specified distance and direction.
      • ATC is required to radar monitor random RNAV routes.
      • Approval for these routes requires a radar environment.
      • Factors that ATC considers in approving random RNAV routes include the capability to provide radar monitoring and compatibility with traffic volume and flow.
      • ATC will radar monitor each flight; however, pilots are responsible for navigating the random RNAV route.
    • Jet Routes and Q Routes
      High Altitude Enroute Chart

ATC Authorizations and Deviations:

  • Pilots may deviate from any provision of part 91.135, provided an ATC authorization is issued by the ATC facility with jurisdiction over the airspace.
  • In the case of an inoperative transponder, ATC may approve operation within a Class A airspace area, which allows the flight to continue to the airport of ultimate destination, including any intermediate stops, or to proceed to a location with suitable repair capabilities.
  • The FAA requires written requests for deviation from any provision in Federal Aviation Regulations Part 91 at least four days before the proposed operation.

Conclusion:

References: