2.1.2, 2.1.3 AIRMETs in the conterminous U.S. are issued as bulletins for the East, West, and Central U.S. in conjunction with area forecast turbulence, icing, and ceiling and visibility, and thus do not comply with template for FIR or series numbering format. This difference is also applicable to Table A6.1, Template for SIGMET and AIRMET messages.
2.1.4 AIRMET in the conterminous U.S. on a routine schedule for icing, turbulence, sustained surface winds, ceiling/visibility and convection. Practices do not include use of ISOL, OCNL or FRQ. This difference is also applicable to Table A6.1, Template for SIGMET and AIRMET messages. The U.S. does not include cloud amount or type in AIRMET.
4.2.1 U.S. practices do require reporting of ISOL, OCNL or FREQ in accordance with the guidance on the use of the terms given in App 6. The United States reports “isolated” (ISOL) when the phenomena affect an area less than approximately 3,000 square miles or are widely separated in time, and widespread (WDSPR) to mean more than 50 percent of the area.
5.1, 5.1.3 The United States does provide for tsunamis in the aerodrome warning. The U.S. issues airport warning messages similar to the ICAO format (Table A6.2, Template for aerodrome warnings) only at selected airports based on a bilateral agreement between the airport authority and the NWS Forecast Office.
ANNEX 4 . AERONAUTICAL CHARTS
Chapter 1 Definitions
Air taxiway The U.S. does not depict defined surfaces for air.taxiing of helicopters.
Danger area The term “danger area” will not be used in reference to areas within the U.S. or in any of its possessions or territories.
Final approach and take.off area (FATO) The U.S. does not depict final approach and take.off areas (FATOs).
Helicopter stand The U.S. does not use this term.
Prohibited area Restricted area The U.S. will employ the terms “prohibited area” and “restricted area” substantially in accordance with the definitions established and, additionally, will use the following terms: “Alert area.” Airspace which may contain a high volume of pilot training activities or an unusual type of aerial activity, neither of which is hazardous to aircraft. “Controlled firing area.” Airspace wherein activities are conducted under conditions so controlled as to eliminate the hazards to nonparticipating aircraft and to ensure the safety of persons and property on the ground. “Warning area.” Airspace which may contain hazards to nonparticipating aircraft in international airspace. “Maneuvering area.” This term is not used by the U.S. “Military operations area (MOA).” An MOA is an airspace assignment of defined vertical and lateral dimensions established outside Class A airspace to separate/segregate certain military activities from IFR traffic and to identify for VFR traffic where these activities are conducted. “Movement area.” Movement area is defined by the U.S. as the runways, taxiways, and other areas of an airport which are utilized for taxiing, take.off, and landing of aircraft, exclusive of loading ramp and parking areas.
Touchdown and lift.off area (TLOF) The U.S. does not use this term.
Chapter 1.1 Definitions
Aerodrome reference point Airport Reference Point is the approximate geometric center of all usable runway surfaces.
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