conditions are encountered, ascend or descend to altitudes
where these conditions do not prevail.
If flight into icing
conditions is unavoidable, proper use of aircraft anti-icing
and deicing systems may
minimize the problems
encountered. Approximately 15 minutes prior to flight into
temperature conditions which could produce frost or icing
conditions, the pilot and co-pilot windshield anti-ice
switches should be set at normaI or high temperature
position (after preheating) as necessary to eliminate
windshield ice. 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 with ice on the aircraft. Maintaina
minimum of 140 knots during sustained icing conditions to
prevent ice accumulation on unprotected surfaces of the
wing. In the event of windshield icing, reduce airspeed to
226 knots or below.
b. Rain. Rain presents no particular problems other
than restricted visibility and occasional incorrect airspeed
c. Taxing. Extreme care must be exercised when
taxiing on ice or slippery runways. Excessive use of either
brakes or power may result in an uncontrollable skid
d. Takeoff. Extreme care must be exercised during
takeoff from ice or slippery runways. Excessive use of
either brakes or power may result in an uncontrollable skid
Keep aircraft attitude as flat as possible and
climb with higher airspeed than usual, so that the lower
surfaces of the aircraft will not be iced by flight at a high
angle of attack
f. Cruise Flight.
(1) Prevention of ice formation.
Prevention of ice
formation is far more effective and satisfactory than
attempts to dislodge the ice after it has formed. If icing
conditions are inadvertently encountered, turn on the anti-
icing systems prior to the first sign of ice formation.
(2) Deicer boots. Do not operate deicer boots
continously. Allow at least 0.5 inch of ice on the wing
deicer boots or 0.25 inch on the antenna deicer boots before
activating to remove the ice. Continued flight in severe
icing conditions should not be attempted. If ice forms on
the wing area aft of the deicer boots, climb or descend to an
altitude where conditions are less severe.
g. Landing. Extreme care must be exercised when
landing on ice or slippery runways. Excessive use of either
brakes or power may result in an uncontrollable skid Ice
accumulation on the aircraft will result in higher stalling
airspeeds due to the change in aerodynamic characteristics
and increased weight of the aircraft due to ice buildup.
Approach and landing airspeeds must be increased
When operating on wet or icy runways, refer to
stopping distance factors shown in Chapter 7.
8-51A. ICING (SEVERE).
The following weather conditions may be conducive
to severe in-flight icing:
(1) Visible rain at temperatures below zero degrees
Celsius ambient air temperature.
(2) Droplets that splash or splatter on impact at
temperatures below zero degrees Celsius ambient air
b. The following procedures for exiting a severe icing
enviromnent are applicable to all flight phases from takeoff
(1) 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
(2) Upon observing the visual cues specified in the
limitations section of the airplane flight manual (Military
Operations Manual) for the identification of severe icing
conditions (reference paragraph 5-33A), accomplish the
(a) 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.
(b) Avoid abrupt and excessive maneuvering
that may exacerbate control difficulties.
(c) Do not engage the autopilot.
(d) If the autopilot is engaged, hold the control
wheel firmly and disengage the autopilot.
uncommanded roll control movement is observed reduce
Change 1 8-33