4-25
Severe Icing Conditions
Severe icing may result from environmental conditions outside of those for which the airplane
is certificated. Flight in freezing rain, freezing drizzle, or mixed icing conditions (supercooled
liquid water and ice crystals) may result in ice build-up on protected surfaces exceeding the
capability of the ice protection system, or may result in ice forming aft of the protected
surfaces. This ice may not be shed using the ice protection systems, and may seriously
degrade the performance and controllability of the airplane.
The following weather conditions may be conductive to severe in-flight icing:
−
Visible rain at temperatures below 0 degrees Celsius ambient air temperature
−
Droplets that splash or splatter on impact at temperatures below 0 degrees Celsius
ambient air temperature
The following procedures are for exiting the severe icing environment and are applicable to all
flight phases from takeoff to landing. Monitor the ambient air temperature. While severe icing
may form at temperatures as cold as -18 degrees Celsius, increased vigilance is warranted at
temperatures around freezing with visible moisture present. If the visual cues specified in
Section 2, Limitations,
for identifying severe icing conditions are observed,
accomplish the following:
−
Report the weather conditions to Air Traffic Control
−
Immediately request priority handling from Air Traffic Control to facilitate a route or an
altitude change to exit the severe icing conditions in order to avoid extended exposure
to flight conditions more severe than those for which the airplane has been certificated.
It should be recalled that flight in severe icing conditions may exceed the capabilities of the
aircraft ice protection systems. If severe icing has been encountered or suspected, even after
having exited icing conditions, the pilot should consider maintaining speeds higher than the
minimum recommended speeds to account for the possibility of degraded flying qualities due
to excessive residual ice.
Section 4 - Normal Procedures (EASA Approved)
Severe Icing Conditions
Pilot's Operating Handbook
Report No: 02406
Issue date: Mar 06, 2020
Page 4-25-1
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