A SNOWTAM is a message describing the conditions of the runways, taxiways and
apron at an aerodrome. During the winter season a SNOWTAM will be issued each
day in the morning, before flying starts. A SNOWTAM is valid for 24 hours, but
there are rules stating that a new SNOWTAM shall be issued sooner if significant
The SNOWTAM consist of different fields, each with its own letter, and the
information is almost entirely given in code. Below are two examples of SNOWTAM
with the most used fields filled in.
Each aerodrome has its own SNOWTAM series, and they are numbered consecutively
for the whole season, starting with 0001.
The SNOWTAM itself contains mostly codes, below are examples of SNOWTAM for
aerodromes with one and two runways.
N) 47 R) 47 T) RWY SANDED)
SWEN0497 ENGM 04200155
(SNOWTAM 0497 A) ENGM B) 04200155
C) 01L F) NIL/NIL/NIL G) XX/XX/XX H) 5/5/5 N) NIL
C) 01R F) NIL/NIL/NIL G) XX/XX/XX H) 5/5/5 N) NIL R) NIL)
SWEN is an international code for SNOWTAM originated in Norway, and the
number indicates how many SNOWTAM has been issued for the aerodrome shown in the
A) ENHF/ENGM is the ICAO 4-letter location indicator for the aerodrome.
B) 04200155 is the day-time group for when the SNOWTAM was issued. The
format is month-day-hour-minute UTC.
C) 05/01L/01R is which runway the SNOWTAM is for. A SNOWTAM
will always tell you the condtions of a runway seen from the end with the lower
designator, for example if the runway orientation is 03/21, then the conditions
for RWY 03 will be in the SNOWTAM.
F) This field show runway contamination (any deposits on the
runway). The runway is divided into three equal parts, and the SNOWTAM will give
the values for each third divided by a slash (/). The following codes are used
to describe the type of contamination:
NIL: Clear and dry
2: Wet or water patches
3: Rime (normally less than 1 mm deep)
4: Dry snow
5: Wet snow
8: Compact or rolled snow
9: Frozen ruts or ridges.
As shown in the ENHF example, there may be more than one code used for each
third of the RWY. If this is done, the codes will show the different layers of
contamination from the top down. 48 thus indicates that there is dry snow on
top of compact snow on the first third of the runway, the next third has ice
(7), while the last third is covered with dry snow on ice (47).
G) This field in a SNOWTAM is the average depth of the contamination,
again for each third of the runway. The depth is given in millimeters, but if
the depth cannot be measured, as would be the case for ice, then the letters XX
H) This field indicates the braking action, the friction on the
runway. Again the runway is divided into three parts, and the numbers are the
mean values for each third. The braking action may be determined by measuring
equipment, or estimated. If measuring equipment have been used, the friction
will always be given in two digits, and an abbreviation stating which equipment
was used is also shown. If the friction have been estimated, a single digit will
39 – 36: Medium/good
35 – 30: Medium
29 – 26: Medium/poor
* If unreliable is used, it is because the contamination is outside the approved
range of whatever equipment is used to measure the braking action. This could
either be because the contamination is too deep, or of a type that the equipment
is not approved for. For example, measured friction by Grip Tester (GRT) on wet
ice is considered to be unreliable and the SNOWTAM will then have the value 9 in
If the friction on the runway has been measured, the type of
equipment used is indicated with the following abbreviations:
GRT: Grip Tester
RFT: Runway friction tester
SFH: Surface friction tester (high pressure tires)
SFL: Surface friction tester (low pressure tires)
SKH: Skiddometer (high pressure tires)
SKL: Skiddometer (low pressure tires)
Any other type of equipment will be stated in clear text.
N) This field shows the conditions on the taxiways associated with the
runway. The codes are the same as for the runway, but the taxiways are not
divided into thirds.
R) This field tells you whats on the apron, again, the codes are the
same as for the runway.
T) This field is a clear text-field. In this field information of significance will be entered. If there is no text in this field, the T) will not
be shown on the SNOWTAM.
SNOWTAM Decode - METAR Format