CFI Instrument Practical Test Standards, FAA-S-8081-9B, June 2001

III. Preflight Preparation

A. Weather Information

2. Weather reports and forecasts
    b. Inflight weather advisories
      1) Hazardous inflight weather advisory service (HIWAS)
        a) Broadcast continuously over selected VORs
          i) AIRMETs
          ii) SIGMETs
          iii) Convective SIGMETs
          iv) AWWs
          v) CWAs
          vi) Urgent PIREPs
        b) Broadcast states "no hazardous weather advisories" when none exist
        c) Includes area within 150 NM
        d) HIWAS update or out-of-service announcements are made on all communication, NAVAID frequencies and EFAS
        e) Broadcast includes
          i) Area covered and time recorded
          ii) Summary of in-flight aviation advisories
          iii) Request for PIREPs
          iv) Recommendation to contact FSS or Flight Watch for more details
      2) En route flight advisory service (EFAS), Flight Watch
        a) Provided by selected FSSs
          i) 122.0 MHz from 5,000 to 17,500 MSL
          ii) Other discrete frequencies from FL 180 to 450
        b) For timely en route weather information tailored to specific flight type, route and altitude
        c) Focal point for receipt and dissemination of PIREPs
        d) Normally available 0600-2200 local time
        e) Contact Flight Watch by stating the name of ARTCC facility serving that area if known or just "Flight Watch" + aircraft ID + nearest VOR
      3) AIRMET (WA)
        a) Significant weather with intensities less than that required for a SIGMET
        b) Issued every 6 hours and whenever updates or corrections are needed
        c) AIRMET Sierra
          i) IFR conditions
          • Ceilings < 1,000 FT and/or
          • Visibility < 3 SM
          • Over at least 50% of area at one time
          ii) Extensive mountain obscuration
        d) AIRMET Tango
          i) Moderate turbulence
          ii) Sustained surface winds at least 30 kts
          iii) Nonconvective LLWS
        e) AIRMET Zulu
          i) Moderate icing
          ii) Freezing levels
      4) SIGMET (WS)
        a) Nonconvective weather potentially hazardous to all aircraft
        b) Issued in conterminous U.S. for
          i) Severe icing (not associated with thunderstorms)
          ii) Severe or extreme turbulence
          iii) Duststorm, sandstorm or volcanic ash lowering visibilities to < 3 SM
          iv) Volcanic eruption
        c) Valid for 4 hours (6 hours if associated with a hurricane)
        d) Designated alphabetically from N through Y
          i) First issuance labeled UWS (urgent weather SIGMET)
          ii) No two different SIGMETs can have the same letter identifier at the same time
      5) Convective SIGMET (WST)
        a) Issued in the 48 states for
          i) Severe thunderstorms due to
          • Surface winds at least 50 kts
          • Surface hail at least ¾ in diameter
          • Tornadoes
          ii) Embedded thunderstorms
          iii) Line(s) of thunderstorms
          iv) Thunderstorm precipitation heavy or greater affecting at least 40% of at least 3,000 sq miles
        b) Any convective SIGMET implies
          i) Severe or greater turbulence
          ii) Severe icing
          iii) LLWS
        c) Issued hourly at 55 minutes after the hour (H + 55) and whenever required
        d) Designated for the eastern (E), central (C) or western (W) U.S.
        e) Numbered suquentially (for each of the 3 areas) from 1 each day, starting at 0000Z
        f) Text consists of a foreast valid for up to 2 hours and sometimes an observation

Greg Gordon MD, CFII