Q6. Q7. Q8. Q9. Q10. What  does  the  element  541003  indicate  in  a TAF? What  does  the  element  QNH2991INS  indicate  in a TAF? When is the abbreviation "FM" used in a TAF? What change group should be used to indicate a forecast   period   of   rain   showers   lasting approximately 30 to 45 minutes? Relative to surface winds, what are the minimum requirements for amending a TAF? PILOT  WEATHER  REPORTS LEARNING   OBJECTIVES:   Identify   the primary reference publication concerning pilot weather  reports  (PIREPs).  Identify  when PIREPs  should  be  submitted  by  pilots,  and when these reports should be forwarded to data collection   centers.   Describe   the   format, elements, and abbreviations used in PIREPs. Pilot-reported   weather   conditions   are   used throughout  the  world  to  supplement  weather  conditions observed  from  the  ground.  There  are  several  types  of reports that are routinely used and should be identified by  Navy  and  Marine  Corps  observers.  As  we mentioned in chapter 1,  “Upper-air Observations,” the AMDAR  code  (WMO  International  code  42-XI)  is automatically  encoded  by  equipment  installed  aboard civilian  aircraft. These  reports  contain  pressure, temperature, and turbulence reports. The CODAR code (WMO   International   code   FM   41-IV)   is   manually encoded  and  transmitted  by  civilian  aircraft  pilots  to report flight-level temperatures and winds, mostly over ocean areas. Many countries throughout the world use national code  forms  to  transmit  pilot-reported  weather conditions.  Most  of  these  code  forms  are  not  readily disseminated  outside  the  originating  country.  Within the United States, its territories, and in some countries where U.S. military forces are stationed, a national code form, the PIREP code, is used to encode and transmit significant weather o b s e r v e d    b y    p i l o t s . NAVMETOCCOMINST  3142.1,  Procedures Governing  Pilot  Weather  Reports  (PIREPS),  outlines procedures for reporting and encoding PIREPS for ail U.S. Navy and Marine Corps weather activities. PILOT-REPORTED  CRITERIA In   the   United   States,   pilots   are   encouraged   to provide a PIREP whenever they encounter any weather during  takeoff,  climb  to  flight  level,  at  flight  level, during descent, or on landing that is of meteorological significance  to  other  aircraft  or  to  surface  activities. Significant weather is defined as any weather that may affect the flight performance of an aircraft, or is capable of causing injury or damage to personnel or property on the ground. Such phenomena as low-level wind shear (LLWS),  thunderstorms  and  associated  thunderstorm phenomena,  icing,  and  turbulence  are  all  considered significant. Pilots  are  also  encouraged  to  make  negative  reports for  conditions  that  are  forecast  but  not  observed  in flight.  For  instance,  if  clear-air  turbulence  (CAT)  or thunderstorms are briefed as occurring in the area and no evidence of the phenomena is observed by a pilot, the pilot should report these conditions as “not occurring.” In particular situations, a briefer may request that a pilot provide information that is not observable from the ground. This may include information on the height of cloud tops, the actual height of cloud bases, the presence of clear levels in a deep layer of assumed solid cloud, or the presence or absence of en route weather over data sparse  areas.  Pilots  are  also  encouraged  to  report  actual measurements of flight level winds and temperatures. To provide a means to evaluate the report, pilots are asked  to  provide  certain  information  with  all  reports. The minimum information required with any PIREP is (a)  the  location  of  the  aircraft  with  respect  to  a navigational aid, (b) the flight level of the aircraft, (c) the type of aircraft, and (d) at least one meteorological element  observed,  with  time  of  occurrence. The observer  evaluates  the  reported  conditions,  and  then prepares the report for transmission. RECORDING  AND  ENCODING INFORMATION As   previously   mentioned,   the   recording   and reporting of PIREP information for Navy and Marine Corps   activities i s    c o v e r e d    i n    d e t a i l    i n NAVMETOCCOMINST  3142.1.  All  military  weather observers,   particularly   those   stationed   within   the United  States,  must  be  thoroughly  familiar  with  this instruction. In addition, forecasters should monitor all PIREPS  received,  paying  particular  attention  to  the those  PIREPS  reporting  hazardous  flight  conditions. PIREP information can also be used to supplement in- flight weather briefings as appropriate. 3-5