ISO 11076:2000

INTERNATIONAL ISO
STANDARD 11076
Second edition
2000-03-15
Aerospace — Aircraft de-icing/anti-icing
methods with fluids
Aéronautique et espace — Méthodes de dégivrage/antigivrage des
aéronefs à l'aide de liquides
Reference number
ISO 11076:2000(E)
©
ISO 2000

---------------------- Page: 1 ----------------------
ISO 11076:2000(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2000
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 � CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 734 10 79
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2000 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 11076:2000(E)
Contents
Foreword.iv
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Abbreviated terms .3
5 General requirements.3
6 Requirements for staff training and qualifications .3
7 Requirements for fluid handling .4
8 Procedures .5
9 General aircraft requirements after de-icing/anti-icing.11
10 Final check before aircraft dispatch .12
11 Pre-takeoff check.12
12 Communications/procedures.13
13 Holdover time.13
Annex A (normative) Guidelines for the application of and holdover times anticipated for ISO type I
fluid/water mixtures.15
Annex B (normative) Guidelines for the application of and holdover times anticipated for ISO type II
and type IV fluid/water mixtures.17
Bibliography.20
© ISO 2000 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 11076:2000(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 11076 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 9, Air cargo and ground equipment.
This second edition cancels and replaces the first edition (ISO 11076:1993), which has been technically revised.
Annexes A and B form a normative part of this International Standard.
Annexes A and B of this International Standard provide guidelines for the application of different types of de-
icing/anti-icing fluids as a function of outside air temperature and of weather conditions. This data requires frequent
updating. ISO/TC 20/SC 9 has agreed to delegating this task under its own guidance to an ISO Maintenance
Agency. The ISO Maintenance Agency designated for this task is:
Society of Automotive Engineers
400, Commonwealth Drive
US-Warrendale, PA 15096-0001
USA
Telephone: + 1 724 776 4841
Telefax: + 1 724 776 0002
Updated annexes to this International Standard can be obtained from ISO Central Secretariat upon request.
iv © ISO 2000 – All rights reserved

---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 11076:2000(E)
Aerospace — Aircraft de-icing/anti-icing methods with fluids
1 Scope
This International Standard establishes the minimum requirements for ground-based aircraft de-icing/anti-icing with
fluids to ensure the safe operation of transport aircraft during icing conditions (see also 8.3.2). All requirements
specified herein are applicable only in conjunction with the referenced International Standards. This International
Standard does not specify requirements for particular aeroplane model types.
Frost, ice or snow deposits, which can seriously affect the aerodynamic performance and/or controllability of an
aircraft, are effectively removed by the application of the procedures specified in this International Standard.
De-icing/anti-icing by mechanical means is not covered by this International Standard.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 11075:1993, Aerospace — Aircraft de-icing/anti-icing Newtonian fluids, ISO type I.
ISO 11077:1993, Aerospace — Self-propelled de-icing/anti-icing vehicles — Functional requirements.
ISO 11078:1994, Aerospace — Aircraft de-icing/anti-icing non-Newtonian fluids, ISO type II.
3 Terms and definitions
3.1
de-icing
procedure by which frost, ice, slush, or snow is removed from an aircraft in order to provide clean surfaces
3.2
de-icing fluid
defined as one of the following:
a) heated water;
b) ISO type I fluid in accordance with ISO 11075;
c) mixture of water and ISO type I fluid;
d) ISO type II, III or IV fluids in accordance with ISO 11078;
e) mixture of water and ISO type II, III or IV fluids
© ISO 2000 – All rights reserved 1

---------------------- Page: 5 ----------------------
ISO 11076:2000(E)
NOTE De-icing fluid is normally applied heated in order to assure maximum efficiency.
3.3
anti-icing
precautionary procedure which provides protection against the formation of frost or ice and accumulation of snow
or slush on treated surfaces of the aircraft for a limited period of time (holdover time)
3.4
anti-icing fluid
defined as one of the following:
a) ISO type I fluid in accordance with ISO 11075;
b) mixture of water and ISO type I fluid;
c) ISO type II, III or IV fluids in accordance with ISO 11078;
d) mixture of water and ISO type II, III or IV fluids
NOTE Anti-icing fluid is normally applied unheated on clean aircraft surfaces but may be applied heated.
3.5
de-icing/anti-icing
combination of the procedures described in 3.1 and 3.3
NOTE It may be performed in one or two steps.
3.6
holdover time
estimated time for which an anti-icing fluid will prevent the formation of frost or ice and the accumulation of snow on
the protected surfaces of an aircraft, under weather conditions as specified in clause 13
3.7
freezing conditions
conditions in which the outside air temperature is below � 3°C (37,4 °F) and visible moisture in any form (such as
fog with visibility below 1,5 km, rain, snow, sleet or ice crystals) or standing water, slush, ice or snow is present on
the runway
3.8
frost/hoarfrost
ice crystals that form from ice saturated air at temperatures below 0 °C (32 °F) by direct sublimation on the ground
or other exposed objects
3.9
freezing fog
suspension of numerous minute water droplets which freezes upon impact with ground or other exposed objects,
generally reducing the horizontal visibility at the earth's surface to less than 1 km (5/8 mile)
3.10
snow
precipitation of ice crystals, most of which are branched, star-shaped or mixed with unbranched crystals and at
temperatures higher than�5 °C (23 °F), the crystals are generally agglomerated into snowflakes
3.11
freezing drizzle
fairly uniform 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
2 © ISO 2000 – All rights reserved

---------------------- Page: 6 ----------------------
ISO 11076:2000(E)
3.12
light freezing rain
precipitation of liquid water particles which freezes upon impact with exposed objects, in the form of drops of more
than 0,5 mm (0,02 in) which, in contrast to drizzle, are widely separated
2
NOTE Measured intensity of liquid water particles are up to 2,5 mm/h (0,10 inch/h) or 25 g/dm /h with a maximum of
2,5 mm (0,10 in) in 6 min.
3.13
rain or high humidity (on cold-soaked wing)
water forming ice or frost on the wing surface, when the temperature of the aircraft wing surface is at or below 0 °C
(32 °F)
3.14
sleet
precipitation in the form of a mixture of rain and snow
NOTE Operation in light sleet is treated as light freezing rain.
3.15
slush
snow or ice that has been reduced to a soft watery mixture by rain, warm temperature and/or chemical treatment
3.16
check
examination of an item against a relevant standard by a trained and qualified person
4 Abbreviated terms
OAT outside air temperature
FP freezing point
5 General requirements
A pilot shall not take off in an aeroplane that has:
a) frost, snow, slush or ice adhering to any propeller, windshield or power plant installation or to airspeed,
altimeter, rate of climb or flight altitude instrument systems;
b) snow, slush or ice adhering to the wings or stabilizing or control surfaces or any frost adhering to the upper
surfaces of wings or stabilizing or control surfaces.
6 Requirements for staff training and qualifications
6.1 Personnel qualifications
De-icing/anti-icing procedures shall be carried out exclusively by trained and qualified personnel.
6.2 Training for crews
Both initial and annual recurrent training for flight crew and ground crew shall be conducted to ensure that all such
crews obtain and retain a thorough knowledge of aircraft de-icing/anti-icing policies and procedures, including new
procedures and lessons learned.
© ISO 2000 – All rights reserved 3

---------------------- Page: 7 ----------------------
ISO 11076:2000(E)
6.3 Subjects to be covered in training
Training shall include the following items as a minimum:
a) effects of frost, ice, slush and snow on aircraft performance;
b) basic characteristics of aircraft de-icing/anti-icing fluids;
c) general techniques for removing deposits of frost, ice, slush, and snow from aircraft surfaces and for anti-icing;
d) de-icing/anti-icing procedures in general and specific measures to be performed on different aircraft types;
e) types of checks required;
f) de-icing/anti-icing equipment operating procedures, including actual operation of equipment;
g) safety precautions;
h) emergency procedures;
i) fluid application and limitations of holdover time tables;
j) de-icing/anti-icing codes and communication procedures;
k) special provisions and procedures for contract de-icing/anti-icing (if applicable);
l) environmental considerations, for example where to de-ice, spill reporting, hazardous waste control;
m) new procedures and development, lessons learned from previous winters.
6.4 Records
Records of personnel training and qualifications shall be maintained for proof of qualification.
7 Requirements for fluid handling
7.1 Environment
De-icing/anti-icing fluid is a chemical product with environmental impact. During fluid handling, avoid any
unnecessary spillage and comply with local environmental and health laws and the manufacturer's safety data
sheet.
7.2 Mixing of different products
Different products shall not be mixed without additional qualification testing.
7.3 Storage
7.3.1 Tanks dedicated to the storage of de-icing/anti-icing fluids shall be used.
7.3.1 Storage tanks shall be of a material of construction compatible with the de-icing/anti-icing fluids, as
specified by the fluid manufacturer.
7.3.2 Tanks shall be conspicuously labelled to avoid contamination.
4 © ISO 2000 – All rights reserved

---------------------- Page: 8 ----------------------
ISO 11076:2000(E)
7.3.3 Tanks shall be inspected annually for corrosion and/or contamination. If corrosion or contamination is
evident, tanks shall be maintained to standard or replaced. To prevent corrosion at the liquid/vapour interface and
in the vapour space, a high liquid level in the tanks is recommended.
7.3.4 The storage temperature limits shall comply with the manufacturer's guidelines.
7.3.5 The stored fluid shall be checked routinely to insure that no degradation/contamination has taken place.
7.4 Pumping
De-icing/anti-icing fluids can show degradation caused by excessive mechanical shearing. Therefore only
compatible pumps and spraying nozzles shall be used. The design of the pumping systems shall be in accordance
with the fluid manufacturer's recommendations.
7.5 Transfer lines
Dedicated transfer lines shall be conspicuously labelled to prevent contamination and shall be compatible with the
de-icing/anti-icing fluids to be transferred.
7.6 Heating
De-icing/anti-icing fluids shall be heated according to the fluid manufacturer's guidelines. The integrity of the fluid
following heating shall be checked periodically.
7.7 Application
7.7.1 Application equipment shall be cleaned thoroughly before being initially filled with a de-icing/anti-icing fluid
in order to prevent fluid contamination.
7.7.2 De-icing/anti-icing fluid in trucks shall not be heated in confined or poorly ventilated areas such as hangars.
7.7.3 The integrity of the fluid at the spray nozzle shall be checked periodically.
8 Procedures
8.1 Need for de-icing/anti-icing
The following procedures specify the recommended methods for de-icing and anti-icing of aircraft on the ground to
provide an aerodynamically clean aircraft.
When aircraft surfaces are contaminated by frozen moisture, they shall be de-iced prior to dispatch. When freezing
precipitation exists and there is a risk of precipitation adhering to the surface at the time of dispatch, aircraft
surfaces shall be anti-iced. If both de-icing and anti-icing are required, the procedure may be performed in one or
two steps (see 3.5). The selection of a one- or two-step process depends upon weather conditions, available
equipment, available fluids and the holdover time to be achieved. If a one-step procedure is used, then both 8.2
and 8.3 apply.
NOTE 1 Slippery conditions can exist on the ground or equipment following the de-icing/anti-icing procedures. Caution
should be exercised, particularly under low humidity or non-precipitating weather conditions due to increased slipperiness.
For guidance regarding fluid limitations, see 8.3.1.
NOTE 2 Where holdover time is critical, a two-step procedure using undiluted type II, III or IV fluid for the second step should
always be considered.
© ISO 2000 – All rights reserved 5

---------------------- Page: 9 ----------------------
ISO 11076:2000(E)
8.2 De-icing
8.2.1 General
Ice, snow, slush, or frost may be removed from aircraft surfaces by heated fluids or mechanical methods. The
following procedures shall be used for their removal when using fluids.
For maximum effect, fluids should be applied close to the surface of the skin to minimize heat loss.
NOTE The heat in the fluid effectively melts any frost, as well as light deposits of snow, slush and ice. Heavier
accumulations require the heat to break the bond between the frozen deposits and the structure; the hydraulic force of the fluid
spray is then used to flush off the residue. The de-icing fluid will prevent refreezing for a period of time depending on aircraft
skin and ambient temperature, the fluid used, the mixture strength and the weather.
8.2.2 Requirements
Ice, snow, slush and frost shall be removed from aircraft surfaces prior to dispatch or prior to anti-icing.
8.2.3 Removal of frost and light ice
A nozzle setting giving a solid cone (fan) spray should be used.
NOTE This ensures the largest droplet pattern available, thus retaining the maximum heat in the fluid. Providing the hot
fluid is applied closed to the aircraft skin, a minimal amount of fluid will be required to melt the deposit.
8.2.4 Removal of snow
A nozzle setting sufficient to flush off deposits shall be used.
The procedure adopted will depend on the equipment available and the depth and type of snow; i.e. light and dry or
wet and heavy. In general, the heavier the deposits the heavier the fluid flow that will be required to remove it
effectively and efficiently from the aircraft surfaces. For light deposits of both wet and dry snow, similar procedures
as for frost removal may be adopted. Wet snow is more difficult to remove than dry snow and unless deposits are
relatively light, selection of high fluid flow will be found to be more effective. Under certain conditions it will be
possible to use the heat, combined with the hydraulic force of the fluid spray to melt and subsequently flush off
frozen deposits. However, where snow has bonded to the aircraft skin, the procedures detailed in 8.2.5 should be
utilized. Heavy accumulation of snow will always be difficult to remove from aircraft surfaces and vast quantities of
fluid will invariably be consumed in the attempt. Under these conditions, serious consideration should be given to
removing the worst of the snow manually before attempting a normal de-icing procedure.
8.2.5 Removal of ice
Heated fluid shall be used to break the ice bond. The method makes use of the high thermal conductivity of the
metal skin.
A jet of hot fluid is directed at close range onto one spot, until the bare metal is just exposed. This bare metal will
then transmit the heat laterally in all directions raising the temperature above the freezing point thereby breaking
the adhesion of the frozen mass to the aircraft surface. By repeating this procedure a number of times, the
adhesion of a large area of frozen snow or glazed ice can be broken. The deposits can then be flushed off with
either a low or high flow, depending on the amount of the deposit.
8.2.6 De-icing fluid application strategy
8.2.6.1 General
For effective removal of snow and ice, the following techniques shall be adopted.
6 © ISO 2000 – All rights reserved

---------------------- Page: 10 ----------------------
ISO 11076:2000(E)
8.2.6.2 Aircraft unique procedures
Certain aircraft can require unique procedures to accommodate design differences. See manufacturer's
instructions.
8.2.6.3 Wings/tailplane
Spray from the tip inboard to the root from the highest point of the surface camber to the lowest. However, aircraft
configurations and local conditions can dictate a different procedure.
8.2.6.4 Vertical surfaces
Start at the top and work down.
8.2.6.5 Fuselage
Spray along the top centre-line and then outboard.
8.2.6.6 Landing gear and wheel bays
The application of de-icing fluid in this area shall be kept to a minimum. De-icing fluid shall not be sprayed directly
onto wheels and brakes.
Accumulations such as blown snow can be removed mechanically. However, where deposits have bonded to
surfaces, they can be removed by the application of hot air or by spraying with hot de-icing fluids.
8.2.6.7 Engines
Deposits of snow should be removed mechanically from engine intakes prior to departure. Any frozen deposits that
have bonded to either the lower surface of the intake or the fan blades may be removed by hot air or other means
recommended by the engine manufacturer.
8.2.7 De-icing location
De-icing/anti-icing near the beginning of the departure runway provides the minimum interval between de-icing/anti-
icing and takeoff.
8.3 Anti-icing
8.3.1 General
Ice, snow, slush, or frost will, for a period of time, be prevented from adhering to or accumulating on aircraft
surfaces by the application of anti-icing fluids. The following procedures shall be adopted when using anti-icing
fluids.
For effective anti-icing, an even film of fluid is required over the prescribed aircraft surfaces which are clean (free of
frozen deposits). For longer anti-icing protection, undiluted, unheated ISO type II, III or IV fluids should be used.
The high fluid pressures and flow rates normally associated with de-icing are not required for this operation and,
where possible, pump speeds should be reduced accordingly. The nozzle of the spray gun should be adjusted to
provide a medium spray.
NOTE ISO type I fluids provide limited holdover effectiveness when used for anti-icing purposes. Little benefit is gained
from the minimal holdover time generated.
© ISO 2000 – All rights reserved 7

---------------------- Page: 11 ----------------------
ISO 11076:2000(E)
8.3.2 Required usage
Anti-icing fluid shall be applied to the aircraft surfaces when freezing rain, snow or other freezing precipitation may
adhere to the aircraft at the time of aircraft dispatch.
8.3.3 Optional usage
Anti-icing fluid may be applied to aircraft surfaces at the time of arrival (preferably before unloading begins) on
short turnarounds during freezing precipitation and on overnight parked aircraft.
NOTE 1 This will minimize ice accumulation prior to departure and often makes subsequent de-icing easier.
On receipt of a frost, snow, freezing drizzle, freezing rain or freezing fog warning from the local meteorological
service, anti-icing fluid may be applied to clean aircraft surfaces prior to the start of freezing precipitation.
NOTE 2 This will minimize the possibility of snow and ice bonding or reduce the accumulation of frozen precipitation on
aircraft surfaces and facilitate subsequent de-icing.
8.3.4 Anti-icing fluid application strategy
CAUTION — Anti-icing fluids may not flow evenly over wing leading edges, horizontal and vertical
stabilizers. These surfaces should be checked to ensure that they are properly coated with fluid.
The process should be continuous and as short as possible.
Anti-icing should be carried out as near to the departure time as operationally possible in order to utilize maximum
holdover time. The anti-icing fluid shall be distributed uniformly over all surfaces to which it is applied. In order to
control the uniformity, all horizontal aircraft surfaces shall be visually checked during application of the fluid. The
correct amount is indicated by fluid just beginning to drop off the leading and trailing edges.
The most effective results are obtained by commencing on the highest part of the wing section and covering from
there towards the leading and trailing edges. On vertical surfaces, start at the top and work down.
The following surfaces shall be protected:
a) wing upper surface and leading edges;
b) horizontal stabilizer upper surface including leading edges and elevator upper surface;
c) vertical stabilizer and rudder;
d) fuselage upper surfaces depending upon the amount and type of precipitation (especially important on centre-
line engined aircrafts).
8.3.5 Anti-icing location
De-icing/anti-icing near the beginning of the departure runway provides the minimum interval between de-icing/anti-
icing and takeoff.
8 © ISO 2000 – All rights reserved

---------------------- Page: 12 ----------------------
ISO 11076:2000(E)
8.4 Limits and precautions
8.4.1 Fluid-related limits
8.4.1.1 Temperature limits
8.4.1.1.1 Two-step de-icing/anti-icing
When performing two-step de-icing/anti-icing, the freezing point of the fluid used for the first step shall not be more
than 3 °C (5 °F) above ambient temperature. (See also Tables A.1 and B.1.)
8.4.1.1.2 ISO type I fluid
CAUTION — ISO type I fluid supplied as a concentrate for dilution with water prior to use shall not be used
undiluted, unless it meets aerodynamic performance and freezing point buffer requirements specified in
ISO 11075.
The freezing point of the ISO type I fluid mixture used for either one-step de-icing/anti-icing or as a second step in
the two-step operation shall be at least 10 °C (18 °F) below the ambient temperature.
8.4.1.1.3 ISO type II, III and IV fluids
CAUTION — Some type IV fluids may, over a period of time under certain low humidity conditions, thicken
and affect the aerodynamic performance of the fluid during subsequent takeoff. If gel residues of type IV
fluids are found at departure, the surface shall be cleaned and reprotected as necessary.
ISO type II, III and IV fluids used as de-icing/anti-icing agents have a lower temperature application limit of �25 °C
(�13 °F). The application limit may be lower, provided a 7 °C (13 °F) buffer is maintained between the freezing
point of the neat fluid and outside air temperature. In no case shall this temperature be lower than the lowest
operational use temperature as defined by the aerodynamic acceptance test.
8.4.1.2 Application limits
An aircraft that has been anti-iced with an undiluted ISO type II, III or IV fluid shall not receive a further coating of
anti-icing fluid directly on top of the contaminated fluid under any circumstances. If it is necessary for an aircraft to
be reprotected prior to the next flight, the external surfaces shall first be de-iced with a hot fluid mix before a further
application of anti-icing fluid is made. (See also Tables A.2, B.2, and B.3.)
8.4.2 Aircraft-related limits
The application of de-icing/anti-icing fluid shall be in accordance with the guidelines of the airframe/engine
manufacturers.
8.4.3 Procedure precautions
8.4.3.1 One-step de-icing/anti-icing is performed with a heated anti-icing fluid (3.4). The fluid used to de-ice
the aircraft remains on aircraft surfaces to provide limited anti-ice capability. The correct fluid concentration shall be
chosen with regard to desired holdover time and is dictated by outside air temperature and weather conditions. See
Tables A.1 and B.1.
CAUTION — Wing-skin temperature can be lower than OAT. A stronger mix (more glycol) may be used
under these conditions.
8.4.3.2 Two-step de-icing/anti-icing: the first step is performed with de-icing fluid (3.2). The correct fluid shall
be chosen with regard to ambient temperature. After de-icing, a separate overspray of anti-icing fluid shall be
applied to protect the relevant surfaces thus providing maximum possible anti-ice capability. The second step is
© ISO 2000 – All rights reserved 9

---------------------- Page: 13 ----------------------
ISO 11076:2000(E)
performed with anti-icing fluid (3.4). The correct fluid concentration shall be chosen with regard to desired holdover
time and is dictated by outside air temperature and weather conditions. (See Tables A.1 and B.1.)
The second step shall be performed before first step fluid freezes (typically within 3 min),
...