Section V. ADVERSE ENVIRONMENTAL CONDITIONS
The purpose of this part is to inform the pilot of the
special precautions and procedures to be followed during
the various weather conditions that may be encountered
in flight. This part is primarily narrative, only those
checklists that cover specific procedures characteristic of
weather operations are included. The checklist in Section
II provides for adverse environmental operations.
8-68. COLD WEATHER OPERATIONS.
Operation of the surface de-ice system in
ambient temperatures below -40°C can
cause permanent damage to the de-ice
Operational difficulties may be encountered during
extremely cold weather, unless proper steps are taken
prior to or immediately after flight. All personnel should
understand and be fully aware of the necessary
procedures and precautions involved.
Preparation For Flight. Accumulations of snow,
ice, or frost on aircraft surfaces will adversely affect
takeoff distance, climb performance and stall speeds 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
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 de-ice, 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
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
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 HI IDLE.
procedures and ground test are the same as those
outlined in Section II.
Taxiing. Whenever possible, taxiing in deep
snow, light weight dry snow or slush should be avoided,
particularly in colder FAT 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 de-ice system, insuring that the
bleed air valves are OPEN and that the condition levers
are in HI IDLE. An outside observer should visually check
wheel rotation to insure brake assemblies have been
deiced. The condition levers may be returned to LOW
IDLE as soon as the brakes are free of ice.
If icing conditions are expected, activate all
anti-ice systems before takeoff, allowing
sufficient time for the equipment to become
If the possibility of ice accumulation on the
horizontal stabilizer or elevator exists,
takeoff will not be attempted. If icing
conditions are expected, activate all anti-ice
systems before takeoff, allowing sufficient
time for the equipment to become effective.
Takeoff. Takeoff procedures for cold weather
operations are the same as for normal takeoff. Taking off
with temperatures 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 de-ice on
and with the ice vanes extended to preclude the
possibility of ice build-up on engine air inlets. Monitor oil
temperatures to insure operation within limits. Before
flight into icing conditions, the pilot and copilot WSHLD
ANTI-ICE switches should be set at NORMAL position.
(1) Brake de-ice. After takeoff from a runway
covered with snow or slush, it may be
advisable to leave brake de-ice ON to