GM3 CAT.OP.MPA.250 Ice and other contaminants -- ground procedures

• ED Decision 2021/005/R found in: Air Operations (965/2012) Part-ARO Part-ORO Part-CAT Part-SPA Part-NCC Part-NCO Part-SPO (Feb 2025)
• ED Decision 2025/008/R found in: Air Operations Revision 24 Part-ARO Part-ORO Part-CAT Part-SPA Part-NCC Part-NCO Part-SPO (Mar 2026)

GM3 CAT.OP.MPA.250 Ice and other contaminants — ground procedures ED Decision 2021/005/R DE-ICING/ANTI-ICING BACKGROUND INFORMATION Further guidance material on this issue is given in the ICAO *Manual of Aircraft Ground De-icing/Anti-icing Operations* (Doc 9640). (a) General (1) Any deposit of frost, ice, snow or slush on the external surfaces of an aircraft may drastically affect its flying qualities because of reduced aerodynamic lift, increased drag, modified stability and control characteristics. Furthermore, freezing deposits may cause moving parts, such as elevators, ailerons, flap actuating mechanism etc., to jam and create a potentially hazardous condition. Propeller/engine/auxiliary power unit (APU)/systems performance may deteriorate due to the presence of frozen contaminants on blades, intakes and components. Also, engine operation may be seriously affected by the ingestion of snow or ice, thereby causing engine stall or compressor damage. In addition, ice/frost may form on certain external surfaces (e.g. wing upper and lower surfaces, etc.) due to the effects of cold fuel/structures, even in ambient temperatures well above 0 °C. (2) Procedures established by the operator for de-icing and/or anti-icing are intended to ensure that the aircraft is clear of contamination so that degradation of aerodynamic characteristics or mechanical interference will not occur and, following anti-icing, to maintain the airframe in that condition during the appropriate HOT. (3) Under certain meteorological conditions, de-icing and/or anti-icing procedures may be ineffective in providing sufficient protection for continued operations. Examples of these conditions are freezing rain, ice pellets and hail snow exceeding certain intensities, high wind velocity, and fast-dropping OAT. No HOT guidelines exist for these conditions. (4) Material for establishing operational procedures can be found, for example, in: (i) ICAO Annex 3 ‘Meteorological Service for International Air Navigation’; (ii) ICAO ‘Manual of Aircraft Ground De-icing/Anti-icing Operations’; (iii) SAE AS6285 ‘Aircraft Ground Deicing/Anti-Icing Processes’; (iv) SAE AS6286 ‘Aircraft Ground Deicing/Anti-Icing Training and Qualification Program’; (iv) SAE AS6332 ‘Aircraft Ground Deicing/Anti-icing Quality Management’; (v) SAE ARP6257 ‘Aircraft Ground De/Anti-Icing Communication Phraseology for Flight and Ground Crews’; (vi) FAA Holdover Time Guidelines (vii) FAA 8900.xxx series Notice ‘Revised FAA-Approved Deicing Program Updates, Winter 20xx-20yy’. (b) Fluids (1) Type I fluid: Due to its properties, Type I fluid forms a thin, liquid-wetting film on surfaces to which it is applied which, under certain weather conditions, gives a very limited HOT. For anti-icing purposes the fluid/water mixture should have a freezing point of at least 10 °C below OAT; increasing the concentration of fluid in the fluid/water mix does not provide any extension in HOT. (2) Type II and Type IV fluids contain thickeners which enable the fluid to form a thicker liquid-wetting film on surfaces to which it is applied. Generally, this fluid provides a longer HOT than Type I fluids in similar conditions. (3) Type III fluid is a thickened fluid especially intended for use on aircraft with low rotation speeds. (4) Fluids used for de-icing and/or anti-icing should be acceptable to the operator and the aircraft manufacturer. These fluids normally conform to specifications such as SAE AMS1424 (Type I) or SAE AMS1428 (Types II, III and IV). Use of non-conforming fluids is not recommended due to their characteristics being unknown. The anti-icing and aerodynamic properties of thickened fluids may be seriously degraded by, for example, inappropriate storage, treatment, application, application equipment, age and in case they are applied on top of non-chemically compatible de-icing fluids. (c) Hold-over protection (1) Hold-over protection is achieved by a layer of anti-icing fluid remaining on and protecting aircraft surfaces for a period of time. With an one-step de-icing/anti-icing procedure, the HOT begins at the commencement of de-icing/anti-icing. With a two-step procedure, the HOT begins at the commencement of the second (anti-icing) step. The hold-over protection runs out: (i) at the commencement of the take-off roll (due to aerodynamic shedding of fluid); or (ii) when frozen deposits start to form or accumulate on treated aircraft surfaces, thereby indicating the loss of effectiveness of the fluid. (2) The duration of hold-over protection may vary depending on the influence of factors other than those specified in the HOT tables. Guidance should be provided by the operator to take account of such factors, which may include: (i) atmospheric conditions, e.g. exact type and rate of precipitation, wind direction and velocity, relative humidity and solar radiation; and (ii) the aircraft and its surroundings, such as aircraft component inclination angle, contour and surface roughness, surface temperature, operation in close proximity to other aircraft (jet or propeller blast) and ground equipment and structures. (3) HOTs are not meant to imply that flight is safe in the prevailing conditions if the specified HOT has not been exceeded. Certain meteorological conditions, such as freezing drizzle or freezing rain, may be beyond the certification envelope of the aircraft. GM3 CAT.OP.MPA.250 Ice and other contaminants — ground procedures ED Decision 2021/005/R DE-ICING/ANTI-ICING BACKGROUND INFORMATION Further guidance material on this issue is given in the ICAO *Manual of Aircraft Ground De-icing/Anti-icing Operations* (Doc 9640). (a) General (1) Any deposit of frost, ice, snow or slush on the external surfaces of an aircraft may drastically affect its flying qualities because of reduced aerodynamic lift, increased drag, modified stability and control characteristics. Furthermore, freezing deposits may cause moving parts, such as elevators, ailerons, flap actuating mechanism etc., to jam and create a potentially hazardous condition. Propeller/engine/auxiliary power unit (APU)/systems performance may deteriorate due to the presence of frozen contaminants on blades, intakes and components. Also, engine operation may be seriously affected by the ingestion of snow or ice, thereby causing engine stall or compressor damage. In addition, ice/frost may form on certain external surfaces (e.g. wing upper and lower surfaces, etc.) due to the effects of cold fuel/structures, even in ambient temperatures well above 0 °C. (2) Procedures established by the operator for de-icing and/or anti-icing are intended to ensure that the aircraft is clear of contamination so that degradation of aerodynamic characteristics or mechanical interference will not occur and, following anti-icing, to maintain the airframe in that condition during the appropriate HOT. (3) Under certain meteorological conditions, de-icing and/or anti-icing procedures may be ineffective in providing sufficient protection for continued operations. Examples of these conditions are freezing rain, ice pellets and hail snow exceeding certain intensities, high wind velocity, and fast-dropping OAT. No HOT guidelines exist for these conditions. (4) Material for establishing operational procedures can be found, for example, in: (i) ICAO Annex 3 ‘Meteorological Service for International Air Navigation’; (ii) ICAO ‘Manual of Aircraft Ground De-icing/Anti-icing Operations’; (iii) SAE AS6285 ‘Aircraft Ground Deicing/Anti-Icing Processes’; (iv) SAE AS6286 ‘Aircraft Ground Deicing/Anti-Icing Training and Qualification Program’; (iv) SAE AS6332 ‘Aircraft Ground Deicing/Anti-icing Quality Management’; (v) SAE ARP6257 ‘Aircraft Ground De/Anti-Icing Communication Phraseology for Flight and Ground Crews’; (vi) FAA Holdover Time Guidelines (vii) FAA 8900.xxx series Notice ‘Revised FAA-Approved Deicing Program Updates, Winter 20xx-20yy’. (b) Fluids (1) Type I fluid: Due to its properties, Type I fluid forms a thin, liquid-wetting film on surfaces to which it is applied which, under certain weather conditions, gives a very limited HOT. For anti-icing purposes the fluid/water mixture should have a freezing point of at least 10 °C below OAT; increasing the concentration of fluid in the fluid/water mix does not provide any extension in HOT. (2) Type II and Type IV fluids contain thickeners which enable the fluid to form a thicker liquid-wetting film on surfaces to which it is applied. Generally, this fluid provides a longer HOT than Type I fluids in similar conditions. (3) Type III fluid is a thickened fluid especially intended for use on aircraft with low rotation speeds. (4) Fluids used for de-icing and/or anti-icing should be acceptable to the operator and the aircraft manufacturer. These fluids normally conform to specifications such as SAE AMS1424 (Type I) or SAE AMS1428 (Types II, III and IV). Use of non-conforming fluids is not recommended due to their characteristics being unknown. The anti-icing and aerodynamic properties of thickened fluids may be seriously degraded by, for example, inappropriate storage, treatment, application, application equipment, age and in case they are applied on top of non-chemically compatible de-icing fluids. (c) Hold-over protection (1) Hold-over protection is achieved by a layer of anti-icing fluid remaining on and protecting aircraft surfaces for a period of time. With an one-step de-icing/anti-icing procedure, the HOT begins at the commencement of de-icing/anti-icing. With a two-step procedure, the HOT begins at the commencement of the second (anti-icing) step. The hold-over protection runs out: (i) at the commencement of the take-off roll (due to aerodynamic shedding of fluid); or (ii) when frozen deposits start to form or accumulate on treated aircraft surfaces, thereby indicating the loss of effectiveness of the fluid. (2) The duration of hold-over protection may vary depending on the influence of factors other than those specified in the HOT tables. Guidance should be provided by the operator to take account of such factors, which may include: (i) atmospheric conditions, e.g. exact type and rate of precipitation, wind direction and velocity, relative humidity and solar radiation; and (ii) the aircraft and its surroundings, such as aircraft component inclination angle, contour and surface roughness, surface temperature, operation in close proximity to other aircraft (jet or propeller blast) and ground equipment and structures. (3) HOTs are not meant to imply that flight is safe in the prevailing conditions if the specified HOT has not been exceeded. Certain meteorological conditions, such as freezing drizzle or freezing rain, may be beyond the certification envelope of the aircraft. ##### GM3 CAT.OP.MPA.250 Ice and other contaminants — ground procedures *ED Decision 2025/008/R* **DE-ICING/ANTI-ICING BACKGROUND INFORMATION** Further guidance material on this issue is given in the ICAO *Manual of Aircraft Ground De-icing/Anti-icing Operations* (Doc 9640). (a) General (1) Any deposit of frost, ice, snow or slush on the external surfaces of an aircraft may drastically affect its flying qualities because of reduced aerodynamic lift, increased drag, modified stability and control characteristics. Furthermore, freezing deposits may cause moving parts, such as elevators, ailerons, flap actuating mechanism etc., to jam and create a potentially hazardous condition. Propeller/engine/auxiliary power unit (APU)/systems performance may deteriorate due to the presence of frozen contaminants on blades, intakes and components. Also, engine operation may be seriously affected by the ingestion of snow or ice, thereby causing engine stall or compressor damage. In addition, ice/frost may form on certain external surfaces (e.g. wing upper and lower surfaces, etc.) due to the effects of cold fuel/structures, even in ambient temperatures well above 0 °C. (2) Procedures established by the operator for de-icing and/or anti-icing are intended to ensure that the aircraft is clear of contamination so that degradation of aerodynamic characteristics or mechanical interference will not occur and, following anti-icing, to maintain the airframe in that condition during the appropriate HOT. (3) Under certain meteorological conditions, de-icing and/or anti-icing procedures may be ineffective in providing sufficient protection for continued operations. Examples of these conditions are freezing rain, ice pellets and hail snow exceeding certain intensities, high wind velocity, and fast-dropping OAT. No HOT guidelines exist for these conditions. (4) Material for establishing operational procedures can be found, for example, in: (i) ICAO Annex 3 ‘Meteorological Service for International Air Navigation’; (ii) ICAO ‘Manual of Aircraft Ground De-icing/Anti-icing Operations’; (iii) SAE AS6285 ‘Aircraft Ground Deicing/Anti-Icing Processes’; (iv) SAE AS6286 ‘Aircraft Ground Deicing/Anti-Icing Training and Qualification Program’; (iv) SAE AS6332 ‘Aircraft Ground Deicing/Anti-icing Quality Management’; (v) SAE ARP6257 ‘Aircraft Ground De/Anti-Icing Communication Phraseology for Flight and Ground Crews’; (vi) FAA Holdover Time Guidelines; *[applicable until 26 March 2028 — ED Decision 2021/005/R]* (vi) FAA Holdover Time Guidelines [*for the corresponding Winter*]; *[applicable from 27 March 2028* — *ED Decision 2025/008/R]* (vii) FAA 8900.xxx series Notice ‘Revised FAA-Approved Deicing Program Updates, Winter 20xx-20yy’. *[applicable until 26 March 2028 — ED Decision 2021/005/R]* (vii) FAA Ground Deicing Program – General Information. *[applicable from 27 March 2028 — ED Decision 2025/008/R]* (b) Fluids (1) Type I fluid: Due to its properties, Type I fluid forms a thin, liquid-wetting film on surfaces to which it is applied which, under certain weather conditions, gives a very limited HOT. For anti-icing purposes the fluid/water mixture should have a freezing point of at least 10 °C below OAT; increasing the concentration of fluid in the fluid/water mix does not provide any extension in HOT. (2) Type II and Type IV fluids contain thickeners which enable the fluid to form a thicker liquid-wetting film on surfaces to which it is applied. Generally, this fluid provides a longer HOT than Type I fluids in similar conditions. (3) Type III fluid is a thickened fluid especially intended for use on aircraft with low rotation speeds. (4) Fluids used for de-icing and/or anti-icing should be acceptable to the operator and the aircraft manufacturer. These fluids normally conform to specifications such as SAE AMS1424 (Type I) or SAE AMS1428 (Types II, III and IV). Use of non-conforming fluids is not recommended due to their characteristics being unknown. The anti-icing and aerodynamic properties of thickened fluids may be seriously degraded by, for example, inappropriate storage, treatment, application, application equipment, age and in case they are applied on top of non-chemically compatible de-icing fluids. (c) Hold-over protection (1) Hold-over protection is achieved by a layer of anti-icing fluid remaining on and protecting aircraft surfaces for a period of time. With an one-step de-icing/anti-icing procedure, the HOT begins at the commencement of de-icing/anti-icing. With a two-step procedure, the HOT begins at the commencement of the second (anti-icing) step. The hold-over protection runs out: (i) at the commencement of the take-off roll (due to aerodynamic shedding of fluid); or (ii) when frozen deposits start to form or accumulate on treated aircraft surfaces, thereby indicating the loss of effectiveness of the fluid. (2) The duration of hold-over protection may vary depending on the influence of factors other than those specified in the HOT tables. Guidance should be provided by the operator to take account of such factors, which may include: (i) atmospheric conditions, e.g. exact type and rate of precipitation, wind direction and velocity, relative humidity and solar radiation; and (ii) the aircraft and its surroundings, such as aircraft component inclination angle, contour and surface roughness, surface temperature, operation in close proximity to other aircraft (jet or propeller blast) and ground equipment and structures. (3) HOTs are not meant to imply that flight is safe in the prevailing conditions if the specified HOT has not been exceeded. Certain meteorological conditions, such as freezing drizzle or freezing rain, may be beyond the certification envelope of the aircraft.