What does the element 541003 indicate in a
What does the element QNH2991INS indicate in
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
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
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
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.
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
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.
observer evaluates the reported conditions, and then
prepares the report for transmission.
RECORDING AND ENCODING
As previously mentioned, the recording and
reporting of PIREP information for Navy and Marine
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.