Aircraft Icing
602.11 (1) In this section, critical surfaces means the wings, control surfaces, rotors, propellers, horizontal stabilizers, vertical stabilizers or any other stabilizing surfaces of an aircraft, as well as any other surfaces identified as critical surfaces in the aircraft flight manual.
(2) No person shall conduct or attempt to conduct a take-off in an aircraft that has frost, ice or snow adhering to any of its critical surfaces.
(3) Despite subsection (2), a person may conduct a take-off in an aircraft that has frost caused by cold-soaked fuel adhering to the underside or upper side, or both, of its wings if the take-off is conducted in accordance with the aircraft manufacturer’s instructions for take-off under those conditions.
(4) Where conditions are such that frost, ice or snow may reasonably be expected to adhere to the aircraft, no person shall conduct or attempt to conduct a take-off in an aircraft unless
(a) for aircraft that are not operated under Subpart 5 of Part VII,
(i) 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, or
(ii) the operator has established an aircraft inspection program in accordance with the Operating and Flight Rules Standards, and the dispatch and take-off of the aircraft are in accordance with that program; and
(b) for aircraft that are operated under Subpart 5 of Part VII, the operator has established an aircraft inspection program in accordance with the Operating and Flight Rules Standards, and the dispatch and take-off of the aircraft are in accordance with that program.
(5) The inspection referred to in subparagraph (4)(a)(i) shall be performed by
(a) the pilot-in-command;
(b) a flight crew member of the aircraft who is designated by the pilot-in-command; or
(c) a person, other than a person referred to in paragraph (a) or (b), who
(i) is designated by the operator of the aircraft, and
(ii) has successfully completed training relating to ground and airborne icing operations under Subpart 4 or relating to aircraft surface contamination under Part VII.
(6) Where, before commencing take-off, a crew member of an aircraft observes that there is frost, ice or snow adhering to the wings of the aircraft, the crew member shall immediately report that observation to the pilot-in-command, and the pilot-in-command or a flight crew member designated by the pilot-in-command shall inspect the wings of the aircraft before take-off.
(7) Before an aircraft is de-iced or anti-iced, the pilot-in-command of the aircraft shall ensure that the crew members and passengers are informed of the decision to do so.
AIM AIR
The Cold-Soaking Phenomenon: Where fuel tanks are located in the wings of aircraft, the temperature of the fuel greatly affects the temperature of the wing surface above and below these tanks. After a flight, the temperature of an aircraft and the fuel carried in the wing tanks may be considerably colder than the ambient temperature.
An aircraft’s cold-soaked wings conduct heat away from precipitation so that, depending on a number of factors, clear ice may form on some aircraft, particularly on wing areas above the fuel tanks. Such ice is difficult to see and, in many instances, cannot be detected other than by touch with the bare hand or by means of a special purpose ice detector.
Clear ice formations could break loose at rotation or during flight, causing engine damage on some aircraft types, primarily those with rear-mounted engines. A layer of slush on the wing can also hide a dangerous sheet of ice beneath.
The formation of ice on the wing is dependent on the type, depth and liquid content of precipitation, ambient air temperature and wing surface temperature. The following factors contribute to the formation intensity and the final thickness of the clear ice layer:
- (a) low temperature of the fuel uplifted by the aircraft during a ground stop and/or the long airborne time of the previous flight, resulting in a situation that the remaining fuel in the wing tanks is subzero. Fuel temperature drops of up to 18°C have been recorded after a flight of two hours;
- (b) an abnormally large amount of cold fuel remaining in the wing tanks causing fuel to come in contact with the wing upper surface panels, especially in the wing root area;
- (c) weather conditions at the ground stop, wet snow, drizzle or rain with the ambient temperature around 0°C is very critical. Heavy freezing has been reported during drizzle or rain even in a temperature range between +8° to +14°C.
As well, cold-soaking can cause frost to form on the upper and lower wing under conditions of high relative humidity. This is one type of contamination that can occur in above-freezing weather at airports where there is normally no need for de-icing equipment, or where the equipment is deactivated for the summer. This contamination typically occurs where the fuel in the wing tanks becomes cold-soaked to below-freezing temperatures because of low temperature fuel uplifted during the previous stop, or cruising at altitudes where low temperatures are encountered, or both, and a normal descent is made into a region of high humidity.
In such instances, frost will form on the under and upper sides of the fuel tank region during the ground turn-around time, and tends to re-form quickly even when removed.
Available test data indicate that this roughness on the wing lower surface will have no significant effect on lift, but it may increase drag and thereby decrease climb gradient capability which results in a second segment limiting weight penalty.
Skin temperature should be increased to preclude formation of ice or frost prior to take-off. This is often possible by refuelling with warm fuel or using hot freezing point depressant fluids, or both.
In any case, ice or frost formations on upper or lower wing surfaces must be removed prior to takeoff. The exception is that takeoff may be made with frost adhering to the underside of the wings provided it is conducted in accordance with the aircraft manufacturer’s instructions.
Aircraft Icing
602.11 (1) In this section, critical surfaces means the wings, control surfaces, rotors, propellers, horizontal stabilizers, vertical stabilizers or any other stabilizing surfaces of an aircraft, as well as any other surfaces identified as critical surfaces in the aircraft flight manual.
(2) No person shall conduct or attempt to conduct a take-off in an aircraft that has frost, ice or snow adhering to any of its critical surfaces.
(3) Despite subsection (2), a person may conduct a take-off in an aircraft that has frost caused by cold-soaked fuel adhering to the underside or upper side, or both, of its wings if the take-off is conducted in accordance with the aircraft manufacturer’s instructions for take-off under those conditions.
(4) Where conditions are such that frost, ice or snow may reasonably be expected to adhere to the aircraft, no person shall conduct or attempt to conduct a take-off in an aircraft unless
(a) for aircraft that are not operated under Subpart 5 of Part VII,
(i) 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, or
(ii) the operator has established an aircraft inspection program in accordance with the Operating and Flight Rules Standards, and the dispatch and take-off of the aircraft are in accordance with that program; and
(b) for aircraft that are operated under Subpart 5 of Part VII, the operator has established an aircraft inspection program in accordance with the Operating and Flight Rules Standards, and the dispatch and take-off of the aircraft are in accordance with that program.
(5) The inspection referred to in subparagraph (4)(a)(i) shall be performed by
(a) the pilot-in-command;
(b) a flight crew member of the aircraft who is designated by the pilot-in-command; or
(c) a person, other than a person referred to in paragraph (a) or (b), who
(i) is designated by the operator of the aircraft, and
(ii) has successfully completed training relating to ground and airborne icing operations under Subpart 4 or relating to aircraft surface contamination under Part VII.
(6) Where, before commencing take-off, a crew member of an aircraft observes that there is frost, ice or snow adhering to the wings of the aircraft, the crew member shall immediately report that observation to the pilot-in-command, and the pilot-in-command or a flight crew member designated by the pilot-in-command shall inspect the wings of the aircraft before take-off.
(7) Before an aircraft is de-iced or anti-iced, the pilot-in-command of the aircraft shall ensure that the crew members and passengers are informed of the decision to do so.
AIM AIR
The Cold-Soaking Phenomenon: Where fuel tanks are located in the wings of aircraft, the temperature of the fuel greatly affects the temperature of the wing surface above and below these tanks. After a flight, the temperature of an aircraft and the fuel carried in the wing tanks may be considerably colder than the ambient temperature.
An aircraft’s cold-soaked wings conduct heat away from precipitation so that, depending on a number of factors, clear ice may form on some aircraft, particularly on wing areas above the fuel tanks. Such ice is difficult to see and, in many instances, cannot be detected other than by touch with the bare hand or by means of a special purpose ice detector.
Clear ice formations could break loose at rotation or during flight, causing engine damage on some aircraft types, primarily those with rear-mounted engines. A layer of slush on the wing can also hide a dangerous sheet of ice beneath.
The formation of ice on the wing is dependent on the type, depth and liquid content of precipitation, ambient air temperature and wing surface temperature. The following factors contribute to the formation intensity and the final thickness of the clear ice layer:
- (a) low temperature of the fuel uplifted by the aircraft during a ground stop and/or the long airborne time of the previous flight, resulting in a situation that the remaining fuel in the wing tanks is subzero. Fuel temperature drops of up to 18°C have been recorded after a flight of two hours;
- (b) an abnormally large amount of cold fuel remaining in the wing tanks causing fuel to come in contact with the wing upper surface panels, especially in the wing root area;
- (c) weather conditions at the ground stop, wet snow, drizzle or rain with the ambient temperature around 0°C is very critical. Heavy freezing has been reported during drizzle or rain even in a temperature range between +8° to +14°C.
As well, cold-soaking can cause frost to form on the upper and lower wing under conditions of high relative humidity. This is one type of contamination that can occur in above-freezing weather at airports where there is normally no need for de-icing equipment, or where the equipment is deactivated for the summer. This contamination typically occurs where the fuel in the wing tanks becomes cold-soaked to below-freezing temperatures because of low temperature fuel uplifted during the previous stop, or cruising at altitudes where low temperatures are encountered, or both, and a normal descent is made into a region of high humidity.
In such instances, frost will form on the under and upper sides of the fuel tank region during the ground turn-around time, and tends to re-form quickly even when removed.
Available test data indicate that this roughness on the wing lower surface will have no significant effect on lift, but it may increase drag and thereby decrease climb gradient capability which results in a second segment limiting weight penalty.
Skin temperature should be increased to preclude formation of ice or frost prior to take-off. This is often possible by refuelling with warm fuel or using hot freezing point depressant fluids, or both.
In any case, ice or frost formations on upper or lower wing surfaces must be removed prior to takeoff. The exception is that takeoff may be made with frost adhering to the underside of the wings provided it is conducted in accordance with the aircraft manufacturer’s instructions.