Page 286 - UK Air Operations Regulations 201121

Part CAT - ANNEX IV - Commercial Air Transport Operations

(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, SAE AMS1428 or equivalent. 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 and
age.
(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.
CAT.OP.MPA.255 Ice and other contaminants — flight procedures
(a) The operator shall establish procedures for flights in expected or actual icing conditions.
(b) The commander shall only commence a flight or intentionally fly into expected or actual
icing conditions if the aircraft is certified and equipped to cope with such conditions.
(c) If icing exceeds the intensity of icing for which the aircraft is certified or if an aircraft not
certified for flight in known icing conditions encounters icing, the commander shall exit the
icing conditions without delay, by a change of level and/or route, if necessary by declaring
an emergency to ATC.
CAT.OP.MPA.255 AMC1 Ice and other contaminants — flight procedures
FLIGHT IN EXPECTED OR ACTUAL ICING CONDITIONS — AEROPLANES
(a) In accordance with Article 25. of Annex IV to Regulation (EC) No 216/2008 (Essential
requirements for air operations), in case of flight into known or expected icing conditions,
the aircraft must be certified, equipped and/or treated to operate safely in such conditions.
The procedures to be established by the operator should take account of the design, the
equipment, the configuration of the aircraft and the necessary training. For these reasons,
different aircraft types operated by the same company may require the development of
different procedures. In every case, the relevant limitations are those which are defined in
the AFM and other documents produced by the manufacturer.
(b) The operator should ensure that the procedures take account of the following:
(1) the equipment and instruments which must be serviceable for flight in icing
conditions;
(2) the limitations on flight in icing conditions for each phase of flight. These limitations
may be imposed by the aircraft’s de-icing or anti-icing equipment or the necessary
performance corrections that have to be made;
(3) the criteria the flight crew should use to assess the effect of icing on the
performance and/or controllability of the aircraft;
(4) the means by which the flight crew detects, by visual cues or the use of the aircraft’s
ice detection system, that the flight is entering icing conditions; and
(5) the action to be taken by the flight crew in a deteriorating situation (which may
develop rapidly) resulting in an adverse effect on the performance and/or
controllability of the aircraft, due to:
(i) the failure of the aircraft’s anti-icing or de-icing equipment to control a build-up
of ice; and/or
(ii) ice build-up on unprotected areas.
(c) Training for dispatch and flight in expected or actual icing conditions. The content of the
operations manual should reflect the training, both conversion and recurrent, which flight
crew, cabin crew and all other relevant operational personnel require in order to comply
with the procedures for dispatch and flight in icing conditions:
(1) For the flight crew, the training should include:
(i) instruction on how to recognise, from weather reports or forecasts which are
available before flight commences or during flight, the risks of encountering
icing conditions along the planned route and on how to modify, as necessary,
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