HOW TO OBTAIN A GOOD WEATHER BRIEFING
The "Anatomy" of a Good Weather Briefing Here are some "tips" on
how to get a good weather briefing. A good weather briefing starts
with developing an awareness of the overall "big picture" before
attempting to get a detailed weather briefing. At many locations,
you can learn about the big picture by listening to the TWEB, an
acronym for Transcribed Weather Broadcast; the TIBS for Telephone
Information Briefing Service (automated FSSs); or PATWAS, for
Pilot's Automatic Telephone Weather Answering Service (nonautomated
FSSs); IVRS, for Interim Voice Response System; or by watching a
good television weather report such as AM Weather. The Airport
Facility Directory, the AOPA Handbook for Pilots, and other aviation
reference materials list the sources of weather information. When
you are ready to call for a weather briefing, the telephone number
for the Federal Aviation Administration (FAA) may be found in these
In a telephone book, look under United States
Government/Department of Transportation/Federal Aviation
Administration/Flight Service Station. Make sure your planned route
of flight is worked out and your flight plan partially completed
before you make the telephone call.
A universal toll free number for Flight Service Stations (FSS) is
being established in conjunction with the FSS Modernization Program.
In the areas of the country where this system is operational, you
can dial 1-800 WX BRIEF (1-800-992-7433) and you will be switched
automatically to the FSS or automated flight service station that
serves the area from which you are calling. When you reach the FSS,
you will be answered by a briefer. If you are connected to one of
our automated FSSs, you will be answered by a recorded announcement
which includes the name of the facility, followed by instructions
for both touch-tone and rotary dial telephone users. Touch-tone
users can elect to talk to a briefer or any of the direct access
services, or can select a menu which identifies those services and
the associated codes for each. The direct access services available
from an automated FSS are recorded weather and aeronautical
information and "fast file" flight plan filing. If you are using a
rotary dial or pulse-tone equipped telephone, you will be switched
automatically to a briefer, who will provide the information
desired; or, if requested, can connect you to one of the direct
So that your preflight briefing can be tailored to your needs,
give the briefer the following information:
- Your qualifications, e.g., student, private, commercial, and
whether instrument rated. - The type of flight contemplated, either
VFR or IFR. - The aircraft's N-number identification. If you do not
know the N-number, the pilot's name. - The aircraft type. - Your
departure point. - Your proposed route of flight. - Your
destination. - Your proposed flight altitude(s). - Your estimated
time of departure (ETD). - Your estimated time enroute.
Request that the briefer provide you with a standard weather
briefing. Then LISTEN to the briefer. The briefer will be following
procedures and phraseology used by FAA personnel providing flight
services. The briefer will advise you of any adverse conditions
along your proposed route of flight. When a VFR flight is proposed
and actual or forecast conditions make VFR flight questionable, the
briefer will describe the conditions and may advise you that "VFR
flight (is) not recommended." If this occurs, or if you feel that
the weather conditions are clearly beyond your capabilities (or that
of your aircraft or equipment), you should consider terminating the
briefing. This will free the briefer to handle other incoming calls.
The briefer will summarize weather reports and forecasts. After
the conclusion of the briefing, if there is anything that you do not
understand about the weather briefing, let the briefer know. If
terminology is used that you do not understand, ask the briefer to
explain it. A briefer who talks too fast should be asked to speak
more slowly. The amount of detail in your weather briefing will
depend upon how complicated the weather situation really is.
Remember, if the weather situation really is "iffy," expect - and
insist upon - a standard weather briefing. It is both your legal
responsibility and your prerogative as a pilot to do so.
Standard Preflight Weather Briefing
At a minimum, your preflight briefing should include the
- Adverse Conditions - Significant meteorological and
aeronautical information that might influence you, the pilot, to
alter your proposed route of flight or even cancel your flight
entirely (e.g., thunderstorms, icing, turbulence, low ceilings or
visibilities, airport closures). Expect the briefer to emphasize
conditions that are particularly significant, such as low level wind
shear, embedded thunderstorms, reported icing, or frontal zones.
- Synopsis - A brief statement as to the cause of the weather
(e.g., fronts or pressure systems) which might affect your proposed
route of flight.
- Current Conditions - When your proposed time of departure is
within 2 hours, a summary of the current weather, including PIREPs,
applicable to your flight will be given.
- Enroute Forecast - Expect the briefer to summarize forecast
conditions along your proposed route in a logical order, i.e.,
climbout, enroute, and descent.
- Destination Forecast - The destination forecast for your
planned ETA will be provided, including any significant changes
within 1 hour before and after your planned time of arrival.
- Winds Aloft - The briefer will summarize forecast winds aloft
for the proposed route. Temperature information will be provided on
- Notice to Airmen (NOTAMs) - "Current" NOTAMs pertinent to your
proposed route of flight will be provided. However, information on
military training routes and areas (MTR and MOA), along with
PUBLISHED NOTAMs and Special Notices, must be specifically
The Standard Preflight Briefing
In person or by phone from an FSS, your preflight weather
briefing should include:
* Adverse conditions, Including SIGMETs, convective SIGMETs,
AIRMETs, and CWAs. * Synopsis * Current conditions, including PIREPs
* Enroute forecast * Destination forecast * Winds aloft forecast *
Don't forget - first give the briefer the flight information
needed to compile a good briefing; then listen to the briefer. Ask
questions If you don't understand or need more information.
Abbreviated Preflight Briefing
Request an Abbreviated Briefing when you need information to
supplement mass disseminated data, update a previous briefing, or
when you need only one or two specific items. Provide the briefer
with appropriate background information, the time you received the
previous information, and/or the specific items needed. You should
indicate the source of the information already received so that the
briefer can limit the briefing to the information that you have not
received, and/or appreciable changes in meteorological conditions
since your previous briefing. To the extent possible, the briefer
will provide the information in the sequence shown for a Standard
Briefing. If you request only one or two specific items, the briefer
will advise you if adverse conditions are present or forecast.
Details on these conditions will be provided at your request.
Outlook Preflight Briefing
You should request an Outlook Briefing whenever your proposed
time of departure is 6 or more hours from the time of the briefing.
The briefer will provide available forecast data applicable to the
proposed flight. This type of briefing is provided for planning
purposes only. You should obtain a Standard Briefing prior to
departure in order to obtain such items as current conditions,
updated forecasts, winds aloft and NOTAMs.
You are encouraged to obtain your preflight briefing by telephone
or in person before departure. In those cases where you need to
obtain a preflight briefing or an update to a previous briefing by
radio, you should contact the nearest FSS to obtain this
information. After communications have been established, advise the
specialist of the type of briefing you require and provide
appropriate background information. You will be provided information
as specified in the above paragraphs, depending on the type of
briefing requested. In addition, the specialist will recommend
shifting to the FLIGHT WATCH frequency when conditions along the
intended route indicate that it would be advantageous to do so.
Following any briefing, feel free to ask for any information that
you or the briefer may have missed. It helps to save your questions
until the briefing has been completed. This enables the briefer to
present the information in a logical sequence, and reduces the
chance of important items being overlooked.
Judgment, which may be defined as the power of arriving at a wise
decision, is the combined result of knowledge, skills, and
experience. You can improve your "Go or No-Go" weather judgment by
setting personal weather minimums that are higher than the legal
minimums. For instance, use a 2,000 foot ceiling and 5 miles
visibility, instead of the legal 1,000 and 3, until you are familiar
with flight under those conditions. You may then gradually reduce
your personal minimums to whatever limits you find comfortable, a or
above the legal limits.
Here are some obvious "DO NOTS" for everyone beginner and pro
* DO NOT fly in or near thunderstorms. Scattered thunderstorms
may be safely circumnavigated, but do not try to fly through or
* DO NOT continue VFR into IFR weather conditions at any time
unless you are IFR rated and have the appropriate Air Traffic
Control (ATC) clearance. Wait it out or turn around if you find
enroute weather lowering to IFR conditions. Do not forget there will
be areas enroute - or even near airports - which are below VFR
minimums, whenever reporting stations are at or near VFR minimums.
Be especially cautious when the temperature and dewpoint spread is
50 or less - fog may result.
* DO NOT proceed "on top," hoping to find a hole at the other end
or hoping to get ATC to "talk you down" if you get caught on top.
* Allow more margin for weather at night. Scud and lower clouds
do not show up very far ahead, particularly when it is a really dark
* DO NOT fly into areas of rain when the air temperature is near
freezing. Ice on the windshield and on the wings makes for poor VFR
flying conditions. Remember too, flight into known icing conditions
is prohibited for all aircraft not properly equipped.
And finally, if you do get caught in weather, tell an FSS or
another ATC facility. They will do their utmost to help you.
THE "GO" OR "NO-GO" DECISION
Preliminary Flight Planning - Getting the "Big Picture"
- AM Weather on public television stations (consult local TV
listings for exact time) - Newspaper weather maps - TV and radio
* Transcribed Radio Broadcasts:
- National Oceanic and Atmospheric Administration (NOAA) Weather
Radio - Transcribed Weather Broadcast (TWEB) on NDBs, VORs, and
available by telephone at some locations
* Recorded Telephone Weather:
- Interim Voice Response System (IVRS) - Pilot's Automatic
Telephone Weather Answering Service (PATWAS) - Telephone Information
Briefing Service (TIBS)
To Obtain a Standard Preflight Weather Briefing:
* In person or by telephone:
- An FSS
If You Go ...
Inflight Weather Update - Sources of inflight weather include:
* Via VHF radio:
- EFAS (FLIGHT WATCH on 122.0 MHz below FL 180 and as published
at FL 180 and above for "real time" weather. - FSS -Centers and
terminal area facilities will broadcast a SIGMET or CWA alert once
on all frequencies upon receipt. - To the extent possible, centers
and terminal area facilities will issue pertinent information on
weather and assist pilots in avoiding hazardous weather areas, when
* Transcribed radio broadcasts:
- Transcribed Weather Broadcasts (TWEBs) - Hazardous Inflight
Weather Advisory Service (HIWAS)
Destination/Arrival Weather can be obtained from the following
sources as available:
* Via VHF radio from:
- Enroute Flight Advisory Service (EFAS) - FSSs or other air
traffic control facilities - Unicom
* Transcribed VHF radio broadcasts:
- Automatic Terminal Information Service (ATIS)
- On site automated weather observations
If You Don't Go ... Your Alternatives
* Delay/postpone (and get a later preflight weather briefing), or
WEATHER INFORMATION SOURCES USED BY BRIEFERS
Area Forecasts (FA)
What are they? Area Forecasts are 12 hour aviation forecasts plus
a 6 hour categorical outlook giving general descriptions of cloud
cover, weather conditions, and potentially hazardous weather which
could impact aircraft operations.
Heights of cloud bases, tops, freezing level, icing, and
turbulence, are referenced to mean sea level (MSL). Ceilings,
however, are given in heights above ground level (AGL). SIGMET type
information affecting a particular area is included in the Area
Forecast and, in addition, a separate SIGMET is always issued.
AIRMETs are issued only when hazardous conditions develop or are
expected to develop which were not adequately covered in the
Categorical outlook terms, describing general ceiling and
visibility conditions for advanced planning purposes, are defined as
* LIFR (Low IFR) - Ceiling less than 500 feet and/or visibility
less than 1 statute mile. * IFR - Ceiling 500 feet to less than
1,000 feet and/or visibility 1 to less than 3 statute miles. * MVFR
(Marginal VFR) - Ceiling 1,000 to 3,000 feet and/or visibility 3 to
5 statute miles, inclusive. * VFR - Ceiling greater than 3,000 feet
and visibility greater than 5 statute miles; includes sky "clear."
The causes of LIFR, IFR, or MVFR are indicated by either ceiling
or restrictions to visibility, or both. The contraction CIG (for
ceiling) and/or weather and obstruction to visibility symbols are
used. If winds (or gusts) of 25 knots or greater are forecast for
the outlook period, the word WIND is also included for all
categories, including VFR.
Example: LIFR CIG - Low IFR due to a low ceiling. Example. IFRF -
IFR due to visibility restricted by fog. Example: MVFR CIG H K -
Marginal VFR due both to ceiling and to visibility restricted by
haze and smoke. Example: IFR CIG R WIND - IFR due both to low
ceiling and to visibility restricted by rain; the wind is expected
to be 25 knots or greater.
When disseminated? Area Forecasts, each covering a broad
geographical area are issued three times a day in the contiguous
United States and Alaska, and four times a day in Hawaii.
The dissemination time differs from area to area. Specific
schedule times for your location can be obtained by calling the
nearest FSS. These forecasts are amended as required.
Sequence (or hourly) Weather Reports (SA)
What are they? Sequence (or hourly) weather reports are specific
aviation weather observations taken at designated reporting sites
throughout the United States. Usually, but not always, these sites
are located on airports.
When produced? Observations are usually made hourly at about 50
minutes past each hour. These observations are transmitted between
55 minutes past each hour and 3 minutes past the hour, and are
generally available at all FSSs within 10 minutes of transmission
time. Of course, special observations are taken whenever changing
weather conditions warrant.
Example of an Hourly Sequence Report:
RDU SA 0150 M50 OVC 10RW - 094/74/59/1009/982/ RB 40/OCNL LTG
Translation - Raleigh-Durham, observation at 0150 ZULU, measured
ceiling 5,000 feet overcast, visibility 10 statute miles; light rain
showers; sea level pressure 1009.4 millibars; temperature 74° F;
dewpoint 59° F; wind from 100° true at 9 knots; altimeter 29.82
inches. Remarks: Rain began at 40 minutes past the hour; occasional
lightning to the distant southwest. (Note: When providing advisories
to departing or arriving aircraft, air traffic control will give
current winds relative to magnetic north.)
Terminal Forecasts (FT)
What are they? Terminal forecasts are issued for specific
airports and generally cover a 5 nautical mile radius from the
center of the runway complex. They contain information on the
expected ceilings, cloud heights and coverage, visibility, weather,
obstructions to vision, and surface winds. They are valid for a 24
hour period. The last 6 hours of each forecast contains a
categorical outlook statement indicating whether VFR, MVFR, IFR, or
LIFR conditions are expected.
Terminal forecasts are written in the following format:
* Station identifier * Date/time group * Ceilings are identified
by the letter "C". * Cloud heights in terminal forecasts are always
reported in hundreds of feet above ground level (AGL). This differs
from area forecasts where, except for ceilings, the bases of clouds
are reported in feet above mean sea level (MSL). * Cloud layers are
stated in ascending order of height. * Visibility is reported in
statute miles (or fractions thereof up to 2 statute miles), but
omitted if the visibility is greater than 6 statute miles. * Weather
and obstructions to vision are displayed in standard weather and
obstructions to visibility symbols. * Surface wind is reported in
tens of degrees from true north and in knots; omitted when less than
10 knots. (Note: Wind direction indicates the direction from which
the wind is blowing.) * Remarks
When disseminated? Terminal forecasts are issued three times a
day based on the time zone in which the forecast office is located
and they are disseminated within 20 minutes after release. Each
forecast is amended according to prescribed criteria when required.
For specific issuance times contact your local FSS.
Example of a Terminal Forecast:
BOS FT 221010 10 SCT C18 BKN 5SW- 3415G25 OCNL C8X1/2SW 12Z C50
BKN 3312G22 04Z MVFR CIG
Translation - Boston terminal forecast for the 22nd day of the
month, valid time 10Z-10Z. Scattered clouds at 1,000 feet (AGL);
ceiling 1,800 feet broken (AGL), visibility 5 statute miles; light
snow showers; surface wind from 3400 at 15 knots with peak gusts to
25 knots; occasionally, ceiling 800 feet obscured; visibility
one-half mile in moderate snow showers. After 12Z, becoming ceiling
5,000 feet broken (AGL); surface wind from 3300 at 12 knots with
gusts to 22 knots. After 04Z and for the last 6 hours of the
terminal forecast, becoming marginal VFR due to ceiling.
Wind and Temperatures Aloft Forecasts (FD)
What are they? Winds and temperatures aloft forecasts contain
upper air velocity and temperature forecasts for some 160 locations
in 48 states. Winds for in between points can be calculated by
interpolation. Winds and temperatures aloft forecasts are 6 hour, 12
hour, and 24 hour forecasts of wind direction to the nearest 10
degrees relative to true north along with wind speed, in knots, for
Temperatures aloft, always in degrees Celsius, are given for all
but the lowest forecast level (with the possible exception of
mountainous areas where temperatures for the lowest level may also
be available, depending upon the elevation of the reporting
When disseminated? Prepared twice daily from 0000Z and 1200Z
radiosonde upper air observations. These forecasts are available
about 4 hours after each observation.
Example and Format of a Winds and Temperatures Aloft Forecast:
Altitude 3,000, 6,000, 9,000, etc. JFK 2925 2833 00 2930-04, etc.
Partial Translation - Kennedy Airport, at 6,000 feet MSL, the
forecast wind is from 2800 true north at 33 knots with a temperature
Inflight Advisories (WS, WST, WA, CWA)
What are they?
An advisory of hazardous weather conditions of concern to all
aircraft issued as necessary.
Convective SIGMET (WST)
An advisory also of concern to all aircraft issued hourly during
periods of hazardous convective weather.
An advisory of hazardous conditions, mainly of concern to small
aircraft issued as necessary except when already part of an area
Center Weather Advisory (CWA)
An unscheduled inflight flow control air traffic and aircrew
advisory. CWAs are considered as "nowcast," rather than a flight
planning product. They normally provide a narration of conditions
existing at the time of issuance and a forecast for the next 2
SIGMETs and AIRMETs warn pilots of potentially hazardous weather.
SIGMETs warn of severe and extreme conditions of importance to all
aircraft, e.g., icing, turbulence, dust storms, sandstorms, etc.
Convective SIGMETs are issued by the National Severe Storms Forecast
Center in Kansas City for the continental United States and warn of
tornadoes, thunderstorms, and hail. Appended hourly to convective
SIGMETs is a 2 to 6 hour outlook that describes the area where and
why expected convective conditions may meet issuance criteria.
AIRMETs concern weather of less severity than SIGMETs or convective
SIGMETs which may be hazardous to aircraft having limited capability
because of lack of equipment, instrumentation, or pilot
When produced? SIGMETs and convective SIGMETs are produced
whenever conditions dictate. Convective SIGMETs are updated on an
hourly basis. AIRMETs are issued only when the conditions were not
adequately described in the area forecast.
Example of an inflight advisory relayed by ATC: "Attention all
aircraft, a line of thunderstorms exists from Williamsport, PA,
southeast to Norfolk, VA. Line moving east at one five knots,
maximum tops to flight level four five zero. Possibility of strong
winds, hail, and heavy rain. Expected to continue beyond two three
zero zero ZULU".
What are they? The best way to eliminate (or at least reduce)
enroute weather surprises is to give - and obtain - pilot reported
inflight weather observations, or PIREPs. A PIREP gives a pilot
valuable information on weather conditions actually being
experienced inflight by other pilots. This information supplements
data reported by ground stations.
When disseminated? Pilot reports are utilized in the receiving
facility immediately, and disseminated to other FAA facilities, the
NWS, and pilots as soon as possible after receipt. They remain in
the system for approximately 3 hours.
Example of PIREP:
LYH UA /OV RIC-LYH 180010/TM 1415/FL065/TP C152/SK 030 SCT-BKN
040 100 OVC/WX FV5 H/TA 06 /TB LGT/RM MDT TURBC SFC-045 DURGC RIC
Translation - Pilot report; from Richmond, VA, to 10 nautical
miles south of Lynchburg, VA; time-1415 UTC; altitude 6,500 feet MSL;
type aircraft, Cessna 152; cloud bases 3,000 feet MSL, coverage
scattered to broken, tops 4,000 feet MSL, higher cloud bases 10,000
feet MSL, coverage overcast; flight visibility 5 statute miles,
haze; temperature 6° C; light turbulence; remarks - moderate
turbulence from the surface to 4,500 feet MSL during climb from
How to Put PIREPs into the System
The best way to get PIREPs into the system is via Flight Watch,
FAA's real time weather service to pilots. Contact Flight Watch and
give (or ask for) PIREPs along your route of flight. If you are
unable to reach Flight Watch, PIREP information should be reported
to the nearest FSS, approach or departure control, or the Air Route
Traffic Control Center (ARTCC) controller. Remember, by providing
real time weather input to the system you will be improving the
quality of the weather information available to pilots following you
over the same area or route. A good PIREP consists of the following:
* Your type of aircraft, altitude, and location (ideally, in
reference to a VOR or significant geographical landmark) * Cloud
cover, including base and top reports * Turbulence and icing *
Visibility restrictions * Outside air temperature (OAT) * Other
significant weather data