NOTES :
1 These holdover times are derived from tests of this fluid having a viscosity as listed in Table 9.
2 Heavy snow, snow pellets, ice pellets, moderate and heavy freezing rain, and hail.
3 These holdover times only apply to outside air temperatures to -10.C (14.F) under freezing drizzle and light freezing rain.
4 Use light freezing rain holdover times if positive identification of freezing drizzle is not possible.
5 Radiational cooling during active frost conditions may reduce holdover times when operating close to the lower end of the outside air temperature range.
CAUTIONS
.
The only acceptable decision criterion, for takeoff without a pre-takeoff contamination inspection, is the shorter time within the applicable holdover time table cell.
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The time of protection will be shortened in heavy weather conditions, heavy precipitation rates, or high moisture content.
.
High wind velocity or jet blast may reduce holdover time.
.
Holdover time may be reduced when aircraft skin temperature is lower than outside air temperature.
.
Fluids used during ground deicing/anti-icing do not provide in-flight icing protection.
APPENDIX “G”
TABLE 8 VISIBILITY IN SNOW VS. SNOWFALL INTENSITY CHART1
Lighting Temperature Range Visibility in Snow (Statute Miles)
.C .F Heavy Moderate Light Very Light
Darkness -1 and above 30 and above ≤1 >1 to 2 . >2 . to 4 >4
Below -1 Below 30 ≤3/4 >3/4 to 1 . >1 . to 3 >3
Daylight -1 and above 30 and above ≤ . > . to 1 . >1 . to 3 >3
Below -1 Below 30 ≤3/8 >3/8 to 7/8 >7/8 to 2 >2
1 Based on : Relationship between Visibility and Snowfall Intensity (TP 14151E), Transportation Development Centre, Transport Canada, November 2003; and Theoretical Considerations in the Estimation of Snowfall Rate Using Visibility (TP 12893E), Transportation Development Centre, Transport Canada, November, 1998.
HOW TO READ THE TABLE
Assume that the daytime visibility in snowfall is 1 statute mile and the temperature is -7.C. Based on these conditions, the snowfall intensity is light. This snowfall intensity is used to determine which holdover time guideline value is appropriate for the fluid in use.
OPERATING PLAN – CENTRAL DEICING FACILITY (continued)
