Introduction

NOTAMs (Notices to Airmen) are essential elements of aeronautical information when preparing for flights. Dispatchers and pilots are required to be aware of them to inform themselves about the operational status of airport infrastructure.

In the event of winter weather conditions, a specific type of NOTAM known as a SNOWTAM is published to report the latest state of the runways. Rain, snow, and ice are all factors that have a considerable impact on take-off and landing performance, and it is absolutely essential to take them into account to assess braking effectiveness and thus calculate the required stopping distance..

Since 2018, a new format for NOTAMs has been defined according to Amendment 39 to Annex 15 of the ICAO.

 

Content

The SNOWTAM describes the current state of a runway using a primary code called the Runway Conditions Code (RWYCC) based on the surface friction level for each 1/3 of the runway length..

The RYWCC is graded on a scale of 0 to 6 (0 being the most slippery, 6 the driest)):

The RWYCC corresponds to a braking efficiency index (Breaking Action) :

This is not included in the SNOWTAM but is used for performance calculations.

The RWYCC is complemented by other indicators:

• Coverage : Percentage of the surface covered for each 1/3 of the runway.
• Depth : Thickness of contamination in millimetres for each 1/3 of the runway.
• Description : Description de l’état pour chaque 1/3 de runway.

Specifically, the SNOWTAM is presented as follows:

ELLX 12220550 06 3/4/5 50/100/NR 06/05/04 DRY SNOW/COMPACTED SNOW/DRY SNOW

• •  Luxembourg airport
  •  Reported on 22nd of december at 05:50 UTC
  • Runway 06/24*

*The track number is the smallest regardless of the track in use.

 Then, for each 1/3 of the runway (X/X/X):

• •  RWYCC : 3 / 4  / 5
  • Coverage : 50% / 100 % / NR
  • Thickness : 06 mm / 05 mm / 03 mm
  • Description : DRY SNOW + 3 mm / COMPACTED SNOW / DRY SNOW - 3 mm

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​Examples

The SNOWTAM appears in the list of NOTAMs for an aerodrome and may include additional information :

SNOWTAM 0456

BIKF 01091200 11/29 4/4/3 60/60/80 05/05/08 WET SNOW/WET SNOW/SLUSH

RWY 11/29 CLEARED FULL WIDTH, SNOWBANKS 0.3M BEYOND RUNWAY EDGES. TWY B SLUSH 10MM. APRON C WET SNOW 15MM

It can also contain information for several runways if applicable :

SNOWTAM 2846

UUEE 01090800

06L 5/5/4 75/75/100 03/03/05 WET/WET SNOW/COMPACTED SNOW

06C 4/4/3 50/75/75 05/05/08 WET SNOW/WET SNOW/SLUSH

06R 3/3/2 100/100/100 10/10/12 COMPACTED SNOW/COMPACTED SNOW/SLUSH

RWY 06L SNOW BANKS 0.5M BEYOND EDGES. RWY 06C CLEARED FULL WIDTH. RWY 06R ADJ SNOW BANKS. TWY A WET SNOW 10MM. APRON B POOR. 01101600

In the United States and Canada, imperial units (here in inches) are used instead of the metric system, as seen here in Saint Johns, Canada. Furthermore, the presentation may slightly differ:

S0095/25 NOTAMR S0084/25

CYYT 2502140856 2502141656 RSC 16 6/6/6 25 PCT 1/8IN DRY SNOW, 25 PCT 1/8IN DRY SNOW, 25 PCT 1/8IN DRY SNOW.

150FT WIDTH. 1FT WINDROWS 10FT ALONG INSIDE WEST AND 10FT ALONG INSIDE EAST RWY EDGE. REMAINING WIDTH 2IN DRY SNOW. SNOW REMOVAL IN PROGRESS. VALID FEB 14 0851 - FEB 14 1651

References 

-ICAO Amendment 39 to Annex 15