Chapter 4 - Preventative Measures and Deicing Procedures

Take-off After Holdover Times Have Been Exceeded

83.  In accordance with the operator's program, take-off may occur after holdover time has been exceeded only if a pre-take-off contamination inspection is conducted and it is determined that critical surfaces are not contaminated.

84.  Subparagraph 602.11(4)(a)(i) of the Canadian Aviation Regulations (CARs) states:  "The aircraft has been inspected immediately prior to take-off to determine whether any frost, ice or snow is adhering to any of its critical surfaces".

85.  Section 622.11 (6.3) of the General Operating and Flight Rules (GOFR) states, in part:  "When holdover time tables are used as decision making criteria, take-off after holdover times have been exceeded can occur only if a pre-take-off contamination inspection is conducted, or the aircraft is de-iced/anti-iced again".

86.  Transport Canada's interpretation of the phrase "inspected immediately prior to take-off", in the ground icing context, is that the inspection must be conducted within five minutes prior to beginning of the take-off roll.

87.  Fluid testing has indicated that this procedure must not be applied to Type I fluids. Type I fluids have very short HOT performance and fluid failure occurs suddenly. The procedure should only be applied to Types II, III and IV anti-icing fluids and then only when the pertinent minimum holdover time equals or exceeds 20 minutes. This practice is not intended to be used continuously every 5 minutes but as a one time only condition after hold over times have been exceeded.

If, after conducting the contamination inspection, it is not possible to take-off within five minutes, the aircraft must return for deicing/anti-icing.