Deicing clears aircraft of winter precipitation and anti-icing protects it from further contamination. The Holdover Time (HOT) Guidelines presented here are the Transport Canada guidance material to help aircrew assess how long their aircraft is protected from further contamination by winter precipitation. These guidelines, prepared and approved by industry specialists and government agencies, provide holdover times for fluids meeting SAE specifications [1, 2] for a wide range of winter weather operating conditions. The ISO and ICAO holdover time documents refer to these same tables.

Table 5 is a list of de/anti-icing fluids that meet the SAE required water spray and high humidity endurance times and that are aerodynamically acceptable [1, 2].

The SAE procedural tables for deicing and anti-icing fluid application are also included [3].

Light snow and very light snow columns are included in the Type I and Type III tables. All other tables provide holdover times for moderate snowfall only. A table linking snow intensity to visibility is provided (Table 8). This table was prepared by Transport Canada [4].

References

1. SAE Aerospace Material Specification, Deicing/Anti-icing Fluids, Aircraft, SAE Type I, AMS 1424, latest revision

2. SAE Aerospace Material Specification, Fluid, Aircraft Deicing/Anti-icing Non-Newtonian (Pseudoplastic), SAE Types II, III, and IV, AMS 1428, latest revision

3. SAE Aerospace Recommended Practice, Aircraft Deicing/Anti-icing Methods with Fluids, ARP 4737, latest revision

4. Relation between Visibility and Snowfall Intensity (TP 14151E), APS Aviation Inc., November 2003

Download the Tables here: PDF version