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|Tag(s)||Weather Risk Management|
International Civil Aviation Organisation (ICAO) defines SNOWTAM as a special series Notice To Airmen notifying the presence, or removal, of hazardous conditions due to snow, ice, slush or standing water associated with snow, slush and ice on the movement area, by means of a specific format (Annex 15 Chapter 2).
A SNOWTAM will be issued by the airport authority, when warranted, to notify users of the presence of, or the removal of, hazardous conditions due to snow, ice, slush or the resulting standing water on the movement surfaces of the aerodrome. The maximum validity period for a SNOWTAM is 24 hours and a new SNOWTAM will be issued whenever there is a significant change in conditions. The following runway condition related changes are considered significant:
- A change in the coefficient of friction of approximately 0.05.
- Changes in depth of deposit greater than the following: 20 mm for dry snow, 10 mm for wet snow, 3 mm for slush.
- A change in the available length or width of a runway of 10 percent or more.
- Any change in the type of deposit or extent of coverage which requires reclassification in Items F or T of the SNOWTAM.
- When critical snow banks exist on one or both sides of the runway, any change in the height or distance from centre line.
- Any change in the conspicuity of runway lighting caused by obscuring of the lights.
- Any other conditions known to be significant according to experience or local circumstances.
Format and Decode
A typical SNOWTAM will consist of a header block, which contains the addressees, the date and time of issue and the SNOWTAM serial number, and the body of the SNOWTAM which contains all of the pertinent airfield information. The airfield information is consistently formatted as items A) through T) as follows:
- AERODROME IDENTIFIER
- DATE/TIME OF OBSERVATION (UTC)
- RUNWAY DESIGNATOR
- CLEARED RUNWAY LENGTH (if less than published length)
- CLEARED RUNWAY WIDTH (if less than published width)
- DEPOSITS OVER TOTAL RUNWAY LENGTH (Observed on each third of the runway)
- MEAN DEPTH OF DEPOSITS (mm) (for each third of total runway length)
- FRICTION MEASUREMENTS OR ESTIMATES (for each third of runway length)
- not used
- CRITICAL SNOWBANKS (if present)
- RUNWAY LIGHTS (if obscured)
- FURTHER CLEARING OPERATIONS (if planned)
- FURTHER CLEARANCE EXPECTED TO BE COMPLETED BY . . . (UTC)
- not used
- TAXIWAY SNOWBANKS
- not used
- NEXT PLANNED OBSERVATION/MEASUREMENT
- PLAIN LANGUAGE REMARKS
Any items not pertinent to existing conditions will not be included in the report. For aerodromes with more than one runway, items C) through P) will be repeated in ascending order of runway identifier. For contaminate codes, friction measurement device codes and complete format and decode information, see ICAO Annex 15, Appendix 2.
- Landing on Contaminated Runways
- Notice To Airmen (NOTAM)
- Surface Friction Measurement and Prediction in Winter Operations