Over the years, Transport Canada (TC) has received numerous requests for advice, information and direction regarding aircraft ground deicing and anti-icing operations. The requests included information on personnel training, equipment requirements, fluid specifications and performance, the use of hold over time (HOT) guidelines, required communications, Canadian Aviation Regulations (CARs), the deicing process, and other related topics.
This guidance document has been generated to serve as an Aircraft Ground Icing resource to the Canadian Aviation Industry.
It is anticipated that the information contained in this TP guidance document will serve Air Operators, Airport Operators, deicing service providers, Central Deicing Facility (CDF) operators, maintenance personnel, managers, Transport Canada Operations Inspectors, and others involved in aircraft ground icing operations.
No attempt has been made to regenerate existing documents, rather, whenever, possible, reference has been made to authoritative documents or organizations with subject matter expertise. In this way the user of this guidance document can pursue a greater depth of subject matter knowledge.
A very small amount of roughness, in thickness as low as 0.40 mm (1/64in.), caused by ice, snow or frost, disrupts the air flow over the lift and control surfaces of an aircraft. The consequence of this roughness is severe lift loss, increased drag and impaired manouverability, particularly during the take off and initial climb phases of flight. Ice can also interfere with the movement of control surfaces or add significantly to aircraft weight. There is no such thing as an insignificant amount of ice.
Ice can form even when the Outside Air Temperature (OAT) is well above 0°C (32°F). An aircraft equipped with wing fuel tanks may have fuel that is at a sufficiently low temperature such that it lowers the wing skin temperature to below the freezing point. This phenomenon is known as cold-soaking. This situation can also occur when an aircraft has been cruising at high altitude for a period of time followed by a quick descent to a landing in a humid environment. Liquid water coming in contact with a wing, which is at a below freezing temperature, will then freeze to the wing surfaces.
Cold-soaking can also be caused by fueling an aircraft with cold fuel. If there is rain or high humidity, ice can form on the cold-soaked wing and accumulate over time. This ice can be invisible to the eye and is often referred to as clear ice. This ice can be detected by performing a tactile inspection or by using specially designed ice detecting systems such as a Ground Ice Detection System (GIDS).
Sheets of clear ice dislodged from the wing or fuselage during takeoff or climb can be ingested by aft fuselage mounted engines, thereby causing a flameout or damage. Sheets of dislodged clear ice can also cause impact damage to critical surfaces such as the horizontal stabilizer.
Canadian Aviation Regulations (CARs) 602.11 states, in part that: "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"; and the associated General Operating Flight Rules Standard (GOFR) 622.11, outlines the requirements of a ground icing program.
The following Regulations and Standards are also applicable:
1.4.1 General Operating Flight Rules and Standards
1.4.2 Commercial Air Service - Aerial Work
1.4.3 Commercial Air Service - Air Taxi Operations
1.4.4 Commercial Air Service - Commuter Operations
1.4.5 Commercial Air Service - Airline Operations