SIGMET
• These messages are intended to provide short
•
term warnings of certain potentially hazardous
weather phenomena.
Warnings are issued for:
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active thunderstorm areas,
lines of thunderstorms,
heavy hail,
severe turbulence or icing,
marked mountain waves,
hurricanes,
widespread sand or dust storms,
volcanic ash,
and low level windshear.
SIGMET
• Sigmets are meant especially to warn
pilots who are already flying about severe
weather
• Sigmets are broadcast by VFR and IFR air
traffic control units, FSS, and are available
on the Navcanada weather website.
SIGMET
Significant Meteorological Report
WSCN31 CWTO 250430
SIGMET A1 VALID 250430/250830
LN TSTMS 30NM WIDE MAX TOPS 400 OBSRVD AT 0400Z FROM
LONDON-TORONTO-PETERBOROUGH. LN MOVG SWD ABT 20
KTS AND INTSFYG. TSTMS MOVG OUT OF AREA BY 0730Z.
Severe Icing or Turbulence not associated with convective clouds
Large area for dust storm or sandstorm (most likely in the Prairies)
Possible volcanic ash clouds, hurricanes and tropical storms (uncommon in Canada)
SIGMET
Line of thunderstorms or active area of thunderstorms
Severe Squall Line
Mountain Waves (mostly Rockies)
Heavy hail (rarely)
Tornado or Water Spout
Low level wind shear
PIREPs (PIlot REPorts)
• PIREPs are reports of weather conditions
encountered by aircraft during flight.
• Pilots are encouraged to file brief reports
of weather conditions especially reports of
any significant atmospheric phenomena
that differ from forecast.
• PIREPs are usually reported to Flight
Service Stations but can be passed along
to Air Traffic Control as well.
PIREP (AIM MET 2-0)
UACN10 CYXU 032133 YZ UA /OV YXU 090010 /TM 2120 /FL080 /TP
PA31 /SK 020BKN040 110OVC /TA 12 /WV 030045 /TB MDT BLO
040 /IC LGT RIME 020040 /RM NIL TURB CYYZ CYHM
TRY TO DECIPHER THIS FOR YOURSELF
Go to:
http://www.tc.gc.ca/civilaviation/publications
/tp14371/met/3-0.htm#3-17
to see how you did!
PIREPS
• Significant weather that can be reported
by PIREP includes, but is not limited to:
– Clear Air Turbulence
– Wind Shear
– Airframe Icing
– Volcanic Ash
– Pilot Estimation of Surface Wind
Levels of Turbulence (AIM-MET 3.7)
INTENSITY AIRCRAFT REACTION
Turbulence that momentarily
causes slight, erratic changes in
altitude and/or attitude (pitch,
roll, yaw).
Report as “Light Turbulence”.
LIGHT
OR Turbulence that causes
slight, rapid and somewhat
rhythmic bumpiness without
appreciable changes in altitude
or attitude.
Report as “Light Chop”.
REACTION INSIDE AIRCRAFT
Occupants may feel a slight
strain against seat belts or
shoulder straps. Unsecured
objects may be displaced
slightly. Food service may be
conducted and little or no
difficulty is encountered in
walking.
Levels of Turbulence (AIM-MET 3.7)
INTENSITY
AIRCRAFT REACTION
REACTION INSIDE AIRCRAFT
MODERATE
Turbulence that is similar to Light
Turbulence but of greater intensity.
Changes in altitude and/or attitude
occur but the aircraft remains in
positive control at all times. It
usually causes variations in
indicated airspeed.
Report as “Moderate Turbulence”.
OR Turbulence that is similar to
Light Chop but of greater intensity.
It causes rapid bumps or jolts
without appreciable changes in
aircraft altitude or attitude.
Report as “Moderate Chop”.
Occupants may feel a slight
strain against seat belts or
shoulder straps. Unsecured
objects may be displaced
slightly. Food service may be
conducted and little or no
difficulty is encountered in
walking.
Levels of Turbulence (AIM-MET 3.7)
INTENSITY AIRCRAFT REACTION
SEVERE
Turbulence that causes large,
abrupt changes in altitude
and/or attitude. It usually
causes large variations in
indicated airspeed. Aircraft
may be momentarily out of
control.
Report as “Severe Turbulence”.
REACTION INSIDE AIRCRAFT
Occupants are forced
violently against seat belts
or shoulder straps.
Unsecured objects are
tossed about. Food service
and walking impossible.
NOTES 1: Occasional: Less than 1/3 of the time. Intermittent: 1/3 to
2/3. Continuous: More than 2/3.
Icing Types and Intensities
INTENSITY ICE ACCUMULATION
Trace
Ice becomes perceptible. The rate of accumulation is slightly greater
than the rate of sublimation. It is not hazardous, even though deicing or anti-icing equipment is not used, unless encountered for
an extended period of time (over 1 hour).
Light
The rate of accumulation may create a problem if flight is prolonged
in this environment (over 1 hour).
Moderate
The rate of accumulation is such that even short encounters become
potentially hazardous, and use of de-icing or anti-icing equipment
or diversion is necessary.
Severe
The rate of accumulation is such that de-icing or anti-icing
equipment fails to reduce or control the hazard. Immediate
diversion is necessary.
*Rime ice:
Rough, milky, opaque ice formed by the instantaneous freezing of
small supercooled water droplets.
*Clear ice:
Glossy, clear, or translucent ice formed by the relatively slow
freezing of large supercooled water droplets.
Icing types
Rime Ice
Clear Ice
(there is a bit of
mixed here too)
PIREP report Mixed Icing