All Air Operators and De/Anti-Icing Service Providers
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The purpose of this Civil Aviation Safety Alert (CASA) is to inform air operators and de/anti-icing service providers on the expected methods of application of SAE Type II, III, and IV aircraft anti-icing fluids (AAF).
Transport Canada (TC) is aware of a potential safety risk described in this CASA associated with the use of minimum AAF quantities and guidance found in a separate industry document.
This CASA serves as an awareness tool to all stakeholders with the recommended methodology to minimize safety risks for air operations in ground icing conditions.
Transport Canada Holdover Time Guidelines and TP 14052 – Guidelines for Aircraft Ground Icing Operations
The Holdover Time (HOT) Guidelines and TP 14052 - Guidelines for Aircraft Ground Icing Operations serve as the principal TC publications applicable to the operations of aircraft in ground icing conditions.
The guidance material in TP 14052 addresses elements critical in an air operator’s ground icing program (GIP), including the use of AAF and the HOT Guidelines, aircraft de/anti-icing procedures, inspections, and training. Due to the breadth of expertise involved in ground icing related activities, TP 14052 also references many industry standards including those published by SAE International.
SAE International publication - Aerospace Specification (AS) 6286 Aircraft Ground Deicing/Anti-Icing Training and Qualification Program
Industry standard AS6286 establishes the minimum training and qualification requirements for ground-based aircraft deicing/anti-icing methods and procedures and is referenced in TP 14052 as a source of information for training and fluid application guidance.
TC was recently made aware that the most recent revision of AS6286 (Revision C) was not published as planned due to limited resource availability, and that the active version (Revision B) of AS6286 remains available where it still contains a table entitled Table B.2.4 Amount of Fluid for Anti-Icing with Thickened Fluids, found in Appendix B.
The quantities provided in this table do not factor in AAF thickness variability. Factors leading to the variability include:
- Outdoor Ambient Temperature (OAT)
- Fluid Type and Brand
- Fluid Viscosity
TC has been advised that Revision C of AS6286 will be published in Spring 2023.
Risks to expected holdover times
Transport Canada tests SAE Type II, III, and IV AAF and publishes their holdover times annually. The holdover time provided by an AAF at any spot on an aircraft’s surface is given by its stabilized thickness after its application and not the overall fluid quantity applied.
There is a risk that a fluid’s expected holdover times may not be attained if the quantities found in ‘Table B.2.4 Amount of Fluid for Anti-Icing with Thickened Fluids’ are used as the basis for aircraft anti-icing.
Furthermore, there exist external factors requiring consideration when applying AAFs effectively, including:
- Aircraft wing configuration
- Prevailing precipitation type and intensity
- Wind intensity and direction
- Spraying distance and fluid application technique
The specific properties of each AAF also have an influence on the quantity required to be sprayed.
In consideration of the safety concern identified, TC recommends that directors of safety, directors of operations, chief pilots, check pilots, pilot instructors, training providers, and service providers ensure that all staff involved in ground icing operations are aware of the adequate application of AAF to ensure the expected holdover time is achieved.
- ‘Table B.2.4 Amount of Fluid for Anti-Icing with Thickened Fluids’, found in Appendix B of AS6286 should not be used.
- AAF must be applied so that it can completely cover the surfaces and form a uniform coating. Enough AAF has been applied when it can be visually confirmed that the AAF is just beginning to run off the leading and trailing edges of the surfaces.
- The AAF application process should be continuous and carried out as near to the departure time as possible to maximize the available holdover time.
- While AAF thickness will vary in time over the profile of the wing surface, it should be distributed uniformly. To control the uniformity of application, all horizontal aircraft surfaces should be visually checked during the application of the AAF.
- Ground Icing Programs (GIP), Standard Operating Procedures (SOP), Winter Operations Manuals (WOM), or other relevant documentation should be reviewed and revised where applicable to reflect the need to ensure that AAF is applied accordingly.
Training on proper fluid application can be achieved through processes described in TP 14502 and methodology in SAE AS6285.
For more information concerning this issue, contact a Transport Canada Centre; or contact Commercial Flight Standards in Ottawa by e-mail at AARTFinfo-InfoAARTF@tc.gc.ca.
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The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.