Revision 6 Feb/2009
A-7
KMD 550/850 FIS Addendum
Appendix A
Understanding Weather Reports
The next series of elements contain data that is read much like that in
METARs and TAFs. Each element starts with a 2-letter designator
which denotes the type of data with that element. The following defines
the element designators:
/TM
: Time as Coordinated Universal Time
/FL
: Altitude as Flight Level
/TP
: Aircraft Type
/SK
: Sky Cover (may include cloud height and coverage)
/WX
: Weather Phenomenon (can include flight visibility, precipitation
and restrictions to visibility.
/TA
: Outside air temperature at altitude in degrees Celsius.
/WV
: Wind (direction in degrees magnetic north and speed in knots)
/TB:
Turbulence (refer to the Airman’s Information Manual)
CAT
- Clear Air Turbulence
CHOP
- Choppy Turbulence
OCNL
- Occasional
NEG
- No Turbulence
ABV
- Above
BLO
- Below
LGT
- Light - Momentarily causes slight, erratic changes in
altitude and/or attitude.
MOD
- Moderate - Greater intensity changes in altitude and/or
attitude, but aircraft remains in positive control at all times.
Usually causes changes in indicated airspeed.
SEV
- Severe - Causes large and abrupt changes to aircraft
altitude and/or attitude. Large variations in indicated airspeed
and momentary loss of control.
EXTRM
- Extreme - Aircraft is violently tossed about and is
nearly impossible to control. May cause structural damage.
/IC
:
Icing (refer to the Airman’s Information Manual)
CLR
- Clear
MX
- Mixed (combination of rime and clear icing)
NEG
- No Icing
ABV
- Above
BLO
- Below
Trace - Ice becomes perceptible. Rate of evaporation is
almost equal to the rate of accumulation. Deicing/anti-icing
equipment is not utilized unless encountered for a period of
time greater than 1 hour.