a. Preparation for Flight. Accumulations of
snow, ice, or frost on aircraft surfaces will adversely
affect takeoff distance, climb performance, and stall
speed to a dangerous degree. Such accumulations
must be removed before flight. In addition to the
normal exterior checks, following the removal of ice,
snow, or frost, inspect wing and empennage surfaces
to verify that these surfaces remain sufficiently cleared.
Also, move all control surfaces to confirm full freedom
of movement. Assure that tires are not frozen to wheel
chocks or to the ground. Use ground heaters, anti-ice
solution, or brake deice to free frozen tires. When heat
is applied to release tires, the temperature should not
exceed 71 °C (160
F). Refer to Chapter 2 for anti-
icing, deicing, and defrosting treatment.
b. Engine Starting. When starting engines on
ramps covered with ice, propeller levers should be in
the FEATHER position to prevent the tires from sliding.
To prevent exceeding torque limits when advancing
condition levers to HIGH IDLE during the starting
procedure, place the power lever in BETA and the
propeller lever in HIGH RPM before advancing the
condition lever to HIGH IDLE.
Procedures are the same as those outlined in
d. Taxiing. Whenever possible, taxiing in deep
snow, light-weight dry snow, or slush should be
avoided, particularly in colder OAT conditions. If it is
necessary to taxi through snow or slush, do not set the
parking brake when stopped. If possible, do not park
the aircraft in snow or slush deep enough to reach the
brake assemblies. Chocks or sandbags should be
used to prevent the aircraft from rolling while parked.
Before attempting to taxi, activate the brake deice
system, insuring that the bleed air valves are open and
that the condition levers are in HIGH IDLE. An outside
observer should visually check wheel rotation to
ensure brake assemblies have been deiced. The
condition levers may be returned to LOW IDLE as
soon as the brakes are free of ice.
If the possibility of ice accumulation on the
horizontal stabilizer or elevator exists, do
not attempt takeoff.
e. Before Takeoff. If icing conditions are
expected, activate all anti-ice systems before takeoff,
allowing sufficient time for the equipment to become
Following takeoff from runways covered
with snow or slush, consideration should
be given to operating the landing gear
through several complete cycles (within
limits) to dislodge ice accumulated from
the spray of slush and water and to prevent
gear freezing in the retracted position.
f. Takeoff. Takeoff procedures for cold
weather operations are the same as for normal takeoff.
Taking off with temperature at or below freezing, with
water, slush, or snow on the runway, can cause ice to
accumulate on the landing gear and can throw ice into
the wheel well areas. Such takeoffs shall be made
with brake deice on and with the ice vanes extended to
preclude the possibility of ice build-up on engine air
inlets. Monitor oil temperature to ensure operation
within limits. Before flight into icing conditions, the
pilot's and copilot's WSHLD ANTI-ICE switches should
be set at NORMAL position.
g. During Flight.
(1) After takeoff from a runway covered with
snow or slush, it may be advisable to leave brake deice
on to dislodge ice accumulated from the spray of slush
or water. Monitor BRAKE DEICE ON annunciator for
automatic termination of system operation and then
turn the switch off. During flight, trim tabs and controls
should also be exercised periodically to prevent
freezing. Ensure that anti-icing systems are activated
before entering icing conditions. Do not activate the
surface deice system until ice has accumulated to 1/2
inch. The propeller deice system operates effectively
as an anti-ice system and it may be operated
continuously in flight. If propeller imbalance due to ice
does occur, it may be relieved by increasing RPM
briefly, then returning to desired setting.
(2) Ice vanes must be extended when
operating in visible moisture or when freedom from
visible moisture cannot be assured, at +5 °C OAT or
less. Ice vanes are designed as an anti-ice system,
not a deice system. After the engine air inlet screens
are blocked, extending the ice vanes will not rectify the
condition. Ice vanes should be retracted at +15 °C
OAT and above to assure adequate engine oil cooling.
(3) Stalling airspeeds should be expected to
increase when ice has accumulated on the aircraft
causing distortion of the wing airfoil. For the same
reason, stall warning devices are not accurate and
should not be relied upon. Keep a comfortable margin
of airspeed above the normal stall airspeed. Maintain
a minimum of 140 knots during sustained icing
conditions to prevent ice accumulation on unprotected