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ADDS - Aviation Digital Data Service


ADDS - METARs Help Page (4 of 5)
Back to METARs Page OR METARs help page 5
  • Flight category definitions:
    Category Ceiling   Visibility
    Low Instrument Flight Rules
    LIFR* (magenta sky symbol)
    below 500 feet AGL and/or less than 1 mile
    Instrument Flight Rules
    IFR (red sky symbol)
    500 to below 1,000 feet AGL and/or 1 mile to less than 3 miles
    Marginal Visual Flight Rules
    MVFR (blue sky symbol)
    1,000 to 3,000 feet AGL and/or 3 to 5 miles
    Visual Flight Rules
    VFR+ (green sky symbol)
    greater than 3,000 feet AGL and greater than 5 miles
    *By definition, IFR is ceiling less than 1,000 feet AGL and/or visibility less than 3 miles while LIFR is a sub-category of IFR.
    +By definition, VFR is ceiling greater than or equal to 3,000 feet AGL and visibility greater than or equal to 5 miles while MVFR is a sub-category of VFR.

  • Cloud coverage symbols:
    Sky symbols
    Automated stations report "CLR" when clouds may exist above 12,000 feet so a square is used to represent this uncertainty whereas an unfilled circle is used for "SKC" which a human reports the sky is completely clear overhead. The abbreviation "OVX" is unofficial but ADDS uses it here to indicate the sky is obscured which is the case when a METAR reports vertical visibility and no cloud information.


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