Tel: +47 75585000
Fax: +47 75585005
Civil Aviation Authority
- Norway -
P.O. Box 243
NO-8001 BODØ
17 OKT

Vinteroperasjoner– avising/anti-ising– prosedyrer

Luftfartstilsynet vil i anledning den forestående vinter og i lys av hendelser og uhell oppstått i forbindelse med mangelfull avising/anti-isings behandling av fly henlede oppmerksomheten på betydningen av BSL JAR OPS 1.345, BSL D 2-1 pkt 4.3.1j og BSL D 3-1 pkt 4.3f.

JAA har utarbeidet en Temporary Guidance Leaflet (TGL) nr 4 datert 01.10.02 publisert i JAA Administrative and Guidance Material Section 4 – Operation.

Innholdet i TGL 4 er gjengitt komplett som vedlegg til denne AIC. Alle operatører, også de som ikke har godkjenning etter BSL JAR OPS, oppfordres til gå gjennom sine prosedyrer og sin informasjon til besetninger og personell som forestår avising/antiisings behandling i lys av TGL 4.

- Vedlegg -

JAA Administrative & Guidance Material

Section Four: Operations, Part Three: Temporary Guidance Leaflets (JAR-OPS)


Note: The material contained in this Leaflet has been issued in accordance with Chapter 10 of Administrative & Guidance Material Section Four: Operations, Part Two: Procedures (JAR-OPS).

The content of this Leaflet is based upon on TGL 4 first published October 1997 and subsequentlyamended as a result of further discussion in ICAO, AEA and FAA. The original text was based on draft NPA text circulated for comment under NPA-OPS-7 as a proposed AMC OPS 1.345 entitled “Ice and other contaminants – Procedures”. Following any future NPA, this material will be added to JAR-OPS in the form of an ACJ. It is therefore authorized for use by the national Authorities on a voluntary basis.

1. General

a. Any deposit of ice, snow or frost on the external surfaces of an aeroplane 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. Also, engine operation may be seriously affected by the ingestion of snow or ice into the engine, causing engine stall or compressor damage. In addition ice may form on the top and underside of fuel tanks containing large quantities of cold fuel even in ambient temperatures well above 0° C.

b. The procedures established by the operator for de-icing/anti-icing are intended to ensure that the airframe is clear of contamination so that neither degradation of aerodynamic characteristics nor mechanical interference will occur and, following anti-icing, to maintain the airframe in that condition during the appropriate holdover time. The de-icing/anti-icing procedures should therefore include type-specific requirements and cover:

(i) Contamination checks, including detection of clear ice and under-wing frost. Limits on the thickness/area of contamination published in the AFM or other manufacturers’ documentation, should be followed;

(ii) De-icing/anti-icing procedures including procedures to be followed if de-icing/anti-icing is interrupted or unsuccessful;

(iii) Post de-icing/anti-icing checks;

(iv) Pre take-off checks;

(v) Pre take-off contamination checks;

(vi) The recording of any incidents relating to de-icing/anti-icing; and

(vii) The responsibilities of all personnel involved in de-icing/anti-icing.

c. Under certain conditions de-icing/anti-icing procedures may be ineffective in providing sufficient protection for continued operations. Examples of these conditions are freezing rain, ice pellets and hail, heavy snow, high wind velocity, fast dropping OAT or any time when freezing precipitation with high water content is present.

d. Material for establishing operational procedures can be found for example in:

- ICAO Doc 9640-AN/940 „Manual of aircraft ground de-icing/anti-icing operations“;

- ISO 11075 (*) ISO Type I fluid;

- ISO 11076 (*) Aircraft de-icing/anti-icing methods with fluids;

- ISO 11077 (*) Self propelled de-icing/anti-icing vehicles-functional requirements;

- ISO 11078 (*) ISO Type II fluid;

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- AEA „Recommendations for de-icing/anti-icing of aircraft on the ground“;

- EUROCAE ED-104/SAE AS 5116 Minimum operational performance specification for

- ground ice detection systems;

- SAE ARP 4737 Aircraft de- anti-icing methods;

- SAE AMS 1424 Type I fluids;

- SAE AMS 1428 Type II, III and IV fluids;

- SAE ARD 50102 Forced air or forced air/fluid equipment for removal of frozen

- Contaminants.

(*) As the revision period of ISO documents in general lasts several years even in the case of fasttrack updating procedure, these documents may not reflect the latest industry standards.

2. Terminology

Terms used in the context of this TGL have the following meanings:

a. Anti-icing. The precautionary procedure that provides protection against the formation of frost or ice and accumulation of snow on treated surfaces of the aeroplane for a limited period of time (holdover time).

b. Anti-icing fluid. Anti-icing fluid includes but is not limited to the following:

(i) Type I fluid;

(ii) Mixture of water and Type I fluid;

(iii) Type II fluid;

(iv) Mixture of water and Type II fluid;

(v) Type IV fluid;

(vi) Mixture of water and Type IV fluid.

Note: On uncontaminated aeroplane surfaces anti-icing fluid is normally applied unheated.

c. Clear ice. A coating of ice, generally clear and smooth, but with some air pockets. It is formed on exposed objects at temperatures at, below or slightly above the freezing temperature by freezing of super-cooled drizzle, droplets or raindrops.

d. Conditions conducive to aeroplane icing on the ground. Freezing fog, freezing precipitation, frost, rain or high humidity (on cold soaked wings), mixed rain and snow and snow.

e. Contamination. Contamination in this context is understood as all forms of frozen or semi-frozen moisture such as frost, snow, slush, or ice.

f. Contamination check. Check of aeroplane surfaces for contamination to establish the need for deicing.

g. De-icing. The procedure by which frost, ice, snow or slush is removed from an aeroplane in order to provide uncontaminated surfaces.

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h. De-icing fluid. De-icing fluid includes but is not limited to the following:

(i) Heated water;

(ii) Type I fluid;

(iii) Mixture of water and Type I fluid;

(iv) Type II fluid;

(v) Mixture of water and Type II fluid;

(vi) Type IV fluid;

(vii) Mixture of water and Type IV fluid.

Note: De-icing fluid is normally applied heated to ensure maximum efficiency

i. De-icing/anti-icing. De-icing/anti-icing is the combination in which the procedure described in subparagraph a. above and/or the procedure described in subparagraph f. above may be performed in one or two steps. One-step de-icing means that de-icing and anti-icing are carried out at the same time using a mixture of anti-icing fluid and water. Two-step de-icing means that de-icing and anti-icing are carried out in two separate steps. The areoplane is first de-iced using heated water only or a heated mixture of de-icing fluid and water. After completion of the de-icing operation a layer of a mixture of anti-icing fluid and water, or of anti-icing fluid only, is to be sprayed over the aeroplane surfaces. The second step will be applied before the first step fluid freezes, typically within threeminutes and, if necessary, area by area.

j. Freezing drizzle. Fairly unifo rm precipitation composed exclusively of fine drops (diameter less than 0.5 mm (0.02 in) very close together, which freezes upon impact with the ground or other exposed objects.

k. Freezing fog. A suspension of numerous minute water droplets which freezes upon impact with the ground or other exposed objects forming a coat of glaze or rime ice. This suspension generally reduces the horizontal visibility at the earth’s surface to less than 1 km (5/8 mile).

l. Freezing precipitation. Corresponds to freezing rain or freezing drizzle.

m. Frost. Ice crystals formed by sublimation when water vapour freezes on the ground or on any other exposed object, which temperature is at or below 0 deg C.

n. Ground Ice Detection System (GIDS). System used during aeroplane ground operations to inform the ground crew and/or the flight crew about the presence of frost, ice, snow or slush on aeroplane monitored surfaces. It can also be used for de-/anti-icing fluid condition monitoring on aeroplane surfaces.

o. Holdover time. The estimated period of time for which any anti-icing will prevent the formation of frost or ice and the accumulation of snow on the protected surfaces of an aeroplane on the ground.

p. Light freezing rain. Precipitation of liquid water particles which freezes upon impact with exposed objects, either in the form of drops of more than 0.5 mm (0.02 in) or smaller drops which, in contrastto drizzle, are widely separated. Measured intensity of liquid water particles are up to 2.5 mm (0.10in) /hour or 25 grams/dm2/hour with a maximum of 0.25 mm (0.01 in) in 6 minutes.

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q. Lowest Operational Use Temperature (LOUT). The lowest temperature at which a fluid has been tested and certified as acceptable in accordance with the appropriate aerodynamic acceptance test while still maintaining the 7 degrees Centigrade freezing point temperature buffer.

r. Post de-icing/anti-icing check. A check after de-icing/anti-icing treatment covering all critical parts of the aeroplane and performed from points offering sufficient visibility of these parts (e.g. from the deicing equipment itself or another elevated piece of equipment) to ensure that these parts are free from any frost, ice, snow, or slush.

s. Pre take-off check. A check to assess whether the applied hold-overtime is still appropriate. This check is normally performed from inside the flight-deck.

t. Pre-take-off contamination check. A check of the critical surfaces for contamination. This check will be performed when the condition of the critical surfaces of the aeroplane cannot be effectively assessed by a pre-take-off check or when the applied hold over time has been exceeded or if any doubt exists of the effectivity of anti-icing This check is normally accomplished from outside the aircraft just before commencing take-off roll.

u. Rain on cold soaked wing. Water forming ice on the wing surface when the temperature of the aeroplane’s wing surface is at or below 0°C (32°F).

v. Mixed rain and snow. Precipitation in the form of a mixture of rain and snow.

w. Slush. Snow or ice that has been reduced to a soft watery mixture by rain, warm temperature and/or chemical treatment.

x. Snow. Precipitation of ice crystals, most of which are branched, star-shaped or mixed with unbranched crystals. At temperature higher than -5°C (23°F), the crystals are generally agglomerated into snowflakes.

3. Fluids

a. Type I fluid. Due to its properties, Type I fluid forms a thin, liquid-wetting film on surfaces to which it is applied, which gives a reduced holdover time depending on the prevailing weather condition. With this type of fluid, increasing the concentration of fluid in the fluid/water mix does not provide any extension in holdover time.

b. Type II/IV fluid. This fluid contains a thickener which enables the fluid to form a thicker liquid-wetting film on surfaces to which it is applied. Generally, this fluid provides a longer holdover time than Type I fluid in similar conditions. With this type of fluid, the holdover time can be extended by increasing the concentration of fluid in the fluid/water mix, up to the maximum holdover time available from undiluted fluid.

c. Type III fluid. A fluid meeting aerodynamic performance requirements applicable to aeroplanes with low rotation speed or short take-off run.

4. Communications

4.1 Before aeroplane treatment.

When the aeroplane is to be treated with the flight crew on board, the flight and ground crews should confirm the fluid to be used, the extent of treatment required, and any aeroplane type specific procedures to be used.

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4.2 Anti-icing code

a. The operator’s procedures should include an anti-icing code, which indicates the treatment the airplane has received. This code provides the flight crew with the minimum details necessary to assess the holdover time (see par. 5 below) and confirms that the aeroplane’s critical surfaces are free of contamination.

b. The procedures for releasing the aeroplane after the treatment should therefore provide the Commander with the anti-icing code.

c. Anti-icing Codes to be used (examples):

(i) „Type I“ at ( -start time) – To be used if /anti-icing treatment has been performed with

a Type I fluid;

(ii) „Type II/100“ at (start time) – To be used if /anti-icing treatment has been performed with undiluted Type II fluid;

(iii) „Type II/75“ at (start time) – To be used if /anti-icing treatment has been performed with a mixture of 75% Type II fluid and 25% water;

(iv) „Type IV/50“ at (start time) – To be used if /anti-icing treatment has been performed with a mixture of 50% Type IV fluid and 50% water.

Note: When a two-step de-icing/anti-icing operation has been carried out, the Anti-Icing Code is determined by the second step fluid.

4.3 After Treatment

The flight crew should receive a confirmation from the ground crew that all de/anti-icing operations are complete and that all personnel and equipment are clear of the aeroplane before reconfiguring or moving the aeroplane.

5. Holdover protection

a. Holdover protection is achieved by a layer of anti-icing fluid remaining on and protecting aeroplane surfaces for a period of time. With a one-step de-icing/anti-icing procedure, the holdover time (HOT) begins at the commencement of de-icing/anti-icing. With a two-step procedure, the holdover time begins at the commencement of the second (anti-icing) step. The holdover time runs out:

(i) At the commencement of take-off roll or

(ii) when frozen deposits start to form or accumulate on treated aeroplane surfaces.

b. The duration of holdover protection may vary subject to the influence of factors other than those specified in the holdover time (HOT) tables. These other factors 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 aeroplane and its surroundings, such as aeroplane component inclination angle,contour and surface roughness, surface temperature, operation in close proximity toother aeroplanes (jet or propeller blast) and ground equipment and structures.

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c. Holdover times are not meant to imply that flight is safe in the prevailing conditions if the specifiedholdover time has not been exceeded. Certain meteorological conditions, such as freezing drizzle orrain, may be beyond the certification envelope of the aeroplane.

d. The operator should publish in the Operations Manual the holdover times in the form of a table or diagram to account for the various types of ground icing conditions and the different types and concentrations of fluids used. However, the times of protection shown in these tables are to be used as guidelines only and are normally used in conjunction with pre-take-off check.

e. References to usable HOT tables may be found in the ‘AEA recommendations for de-/anti-icing aircraft on the ground’ as well as in the ISO 11076 Document.

6. Procedures to be used

a. Operator’s procedures should ensure that:

(i) When aeroplane surfaces are contaminated by ice, frost, slush or snow, they are deiced prior to take-off; according to the prevailing conditions removal of contaminants may be performed with mechanical tools, fluids (including hot water), infra-read heat or forced air.

(ii) Account is taken of the wing skin temperature versus OAT, as this may affect:

A. The need to carry out aeroplane de-icing/anti-icing; and

B. The performance of the de-icing/anti-icing fluids.

(iii) When freezing precipitation exists or there is a risk of precipitation, which is contaminating the surfaces at the time of take-off, aeroplane critical surfaces should be antiiced.

If both de-icing and anti-icing are required, the procedure may be performed in a oneortwo-step process depending upon weather conditions, available equipment, available fluids and the holdover time to be achieved; when de-icing/anti-icing is performed in one step, it should not be assumed that a complete covering by fluid guarantees that de-icing has been carried out correctly, and that all contamination has been removed.

(iv) When an aeroplane is anti-iced and longer holdover times are needed/desired, use of undiluted Type II or Type IV fluid is considered;

(v) All restrictions relative to temperatures (OAT), Lowest Operational Use Temperature (LOUT), fluid application temperature and fluid application pressure, published by the fluid manufacturer and/or aeroplane manufacturer, are followed. Procedures, limitations and recommendations to prevent the formation of fluid residues are followed.

(vi) During conditions conducive to aeroplane icing on the ground or after de-icing/antiicing, an aeroplane is not dispatched for departure unless it has been given a contamination check or a post de-icing/anti-icing check by a trained and qualified person. This check should cover all critical surfaces of the aeroplane and be performed from points offering sufficient accessibility to these parts. To ensure that there is no clear ice on suspect areas, it may be necessary to make a physical check (e.g. touch);

(vii) The required entry is made in the Technical Log. (See AMC OPS 1.915, par. 2, Section;

(viii) The Commander continually monitors the environmental situation after the performed de-icing/anti-icing treatment. Prior to take-off he assesses whether the applied hold-over timeis still appropriate.

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(ix) The Commander performs a pre-take-off check prior to take-off when precipitation existsafter anti-icing treatment. Special method and/or equipment may be necessary to perforethis check at night time or in extreme adverse weather conditions.

(x) Where any doubt exists as to whether or not any deposit may adversely affect theaeroplane’s performance and/or controllability, the Commander does not commence take-offbefore performing a pre-take-off contamination check (see 2 p. above) in order to verifyaeroplane’s critical surfaces to be free of contamination. If this check cannot be performedjust prior take-off, a new complete de-icing/anti-icing treatment should be made.

(xi) When a Ground Ice Detection System (GIDS) is used to perform an aeroplane surfacescheck prior to and/or after a treatment, the GIDS should be considered a part of theprocedure. The use of GIDS should be performed by trained personnel.

7. Special operational considerations

a. The use of de-icing/anti-icing fluids has to be in accordance with the aeroplane manufacturer documentation. This is particular true for thickened fluids to assure sufficient „flow-off“ during takeoff.

b. The operator should comply with any operational requirements such as an aeroplane mass decrease and/or a take-off speed increase when associated with a fluid application for certain types of aeroplanes.

c. The operator should take into account any flight handling procedures (stick force, rotation speed and rate, take-off speed, aeroplane attitude etc.) laid down by the aeroplane manufacturer when associated with a fluid application.

d. The limitations or handling procedures resulting from the application of b. or c. above should be part of the flight crew pre take-off briefing.

8. Training requirements

a. An operator should establish-appropriate initial and recurrent de-icing/anti-icing training programmes (including communication training) for flight crew and those of his ground crew who are involved in de-icing/anti-icing.

b. These de-icing/anti-icing training programmes should include additional training if any of the following will be introduced:

(i) A new procedure;

(ii) A new type of fluid and/or equipment; and

(iii) A new type(s) of aeroplane.

9. Subcontracting (see AMC OPS 1.035 sections 4 and 5)

The operator should ensure that the subcontractor is aware of the operator’s requirements in respect of:

a. The fluids to be used;

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b. Any specific aeroplane requirements (e.g. no-spray areas, APU operation etc.);

c. The de-icing procedures.