by Yvan Chabot, A/Chief, Commercial Flight Standards, Civil Aviation, Transport Canada
With winter on the horizon, the aviation community needs to remain alert to the risks of flying in snow and icing conditions. Transport Canada (TC) is providing this information to renew everyone’s awareness regarding aircraft operations in icing conditions.
The Impact of Ice and Snow on Aircraft and the Importance of De-icing and Anti-icing Inspections
Research and past incidents have shown that even a thin layer of frost can disrupt airflow over an aircraft’s lift and control surfaces, potentially leading to increased drag, loss of lift and impaired maneuverability. Additionally, ice can increase the aircraft’s weight, interfere with control surface movement or hinder the functionality of critical sensors. Therefore, it is crucial to ensure that all critical surfaces of an aircraft are free from contamination before take-off.
This can be verified by the pilot-in-command (PIC) or by trained and qualified personnel through a pre-take-off contamination inspection. The PIC must ensure that aircraft critical surfaces are free of contamination prior to take-off. If the inspection is delegated, an inspection report must be provided to the PIC, who must confirm understanding. Detailed communication guidelines should be in the operator’s manual/ground icing program (GIP), as applicable.
Holdover Time Guidelines
The holdover times (HOT) for aircraft de/anti-icing fluids (ADF) are available in the Transport Canada HOT Guidelines. The HOT Guidelines indicate how long ADFs remain effective against numerous icing conditions. Since various factors may influence these times (e.g., precipitation intensity or temperature change, prevailing winds) the PIC must be aware of these factors and adjust the applicable HOT accordingly. The operators’ manuals/GIP should outline these factors and procedures when using the HOT Guidelines.
Aircraft De/Anti-icing Fluid Considerations
Operators requiring a GIP must have a training component that ensures all personnel applying ADF be properly trained (e.g., use consistent application techniques, inspection procedures).
Only ADFs stored, dispensed and applied according to manufacturers’ instructions should be used, as these have been tested against industry standards. It is important to also ensure that ADFs are within specifications (e.g., lowest on-wing viscosity [LOWV], highest on-wing viscosity [HOWV]) to ensure that holdover times can be safely attained and that the ADF can be used down to its Lowest Operational Use Temperature (LOUT). Using fluids not within their specifications could impact their expected performance and compromise take-off performance.
Recommended Actions for Safe Operations
Pilots, service providers and other personnel involved in de/anti-icing operations should familiarize themselves with the applicable Canadian Aviation Regulations (CARs) and Standard 622 of the General Operating and Flight Rules Standards (GOFRS)—Ground Icing Operations. They should also adhere to procedures recommended by the aircraft manufacturer and comply with all company operations manual (COM) provisions.
Guidance Documents
- Transport Canada’s TP 14052—Guidelines for Aircraft Ground Icing Operations provides detailed information on application methods, fluid types and more. It is a valuable resource for ensuring safe operations in ground icing conditions.
- The holdover times for SAE-qualified de/anti-icing fluids are obtainable in the Transport Canada HOT Guidelines.
By adhering to these best practices and guidelines, pilots, operators and service providers can ensure safe and efficient operations during the winter season. Maintaining vigilance and proper procedures will help mitigate the risks associated with flying in icy conditions, ensuring the safety of all involved.