Holdover time (HOT) guidelines for de-icing aircraft

From Transport Canada

The holdover time (HOT) guidelines provide estimates of how long aircraft anti-icing fluids will be effective. The HOT guidelines are for the application of de-icing and anti-icing fluids to an aircraft on the ground.

The document, which is updated and reissued every year, contains several tables with explanatory notes. The guidelines in the tables provide aircraft flight crews with decision-making criteria.

The criteria are based on:

  • temperature
  • type of precipitation
  • rate of precipitation
  • type of de-icing and/or anti-icing fluid

The table provides safe holdover times based on each of these factors.

Normally, aircraft should not take off after the holdover time has expired. Take-off is then allowed only if a pre-take-off contamination inspection is done, or the aircraft is de-iced/anti-iced again.

The HOT guidelines should be used together with the Guidelines for Aircraft Ground-Icing Operations (TP 14052). This document covers the following subjects related to aircraft de-icing:

  • roles and responsibilities
  • training and testing
  • personnel safety
  • environmental issues
  • operational issues
  • facilities
  • emergencies
  • due diligence

Holdover time rules and all other airport and aerodrome rules are based on Part III (Airports, Aerodromes and Heliports) of the Canadian Aviation Regulations.

Contact us about HOT guidelines

Transport Canada
Civil Aviation Communications Centre

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