Transcript Cold Weather Operations

Cold Weather Operations
REFERENCES
FM 1-202, Environmental Flight, February 1983
FM 1-301, Aeromedical Training for Flight Personnel, May 1987
TC 1-218, Aircrew Training Manual Utility Aircraft, March 1993
Aircraft Operator’s Manual
AR 95-1, Flight Regulations, Sept. 1997
Meteorology Education and Training Website
(http://meted.ucar.edu/icing)
OUTLINE
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Cold Injury Factors
Types of Cold Injuries
Cold Injury Prevention
Flight Operations and Weather
Flight Techniques
Cold Injury Factors
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Defensive Position - Static
Age <17 or >40
Prior cold injury
Fatigue level
Training and experience
Nutrition, activity, drugs and medication,
especially alcohol.
Injuries
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Dehydration
Trenchfoot
Frostbite
Hypothermia
Dehydration
• Loss of water or the elements of water.
• As prevalent in cold regions as it is in hot,
dry areas.
• More difficult in realizing the amount of
water loss due to cold and amount of
absorbing clothes worn in cold weather.
Trenchfoot
• Tissue injury sustained as a result of prolonged
exposure to cold temperatures (usually greater
than 48 hours) in a damp or wet environment.
• Occurs between 32 and 50 degrees F.
• Because early stages are not painful, individual
must be alert and use preventative measures.
• Treatment - Dry and Warm the injury
Frostbite
• Freezing of a body part by exposures to
temperatures below freezing.
• Strong, sustained winds substantially increase
the probability of injury.
• Classification: Superficial or Deep.
• Treatment and management are based solely
upon the classification.
• Treatment - Gradually warm area to body temp
Hypothermia
• Gradual or rapid cooling of the body core
temperature.
• Begins to cause damage at 96o F.
• Individual may not be aware of the impending
danger because of a feeling of well being.
Cold Injury Prevention
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Keep the body dry.
Limit exposure to the cold.
Avoid wearing wet clothing.
Keep activity below perspiration level.
Avoid direct contact of bare skin and cold metal.
Avoid alcohol intake.
Monitor the Wind Chill Factor
WIND CHILL CHART FOR FAHRENHEIT TEMPERATURES (0 F)
ACTUAL THERMOMETER READING (0 F)
ESTIMATED
WIND SPEED
(IN MPH)
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
EQUIVALENT TEMPERATURE (0 F)
CALM
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
5
48
37
27
16
6
-5
-15
-26
-36
-47
-57
-60
10
40
28
16
4
-9
-21
-33
-46
-58
-70
-83
-95
15
36
22
9
-5
-18
-32
-45
-58
-72
-85
-99
-112
20
32
18
4
-10
-25
-39
-53
-67
-82
-96
-110
-124
25
30
16
0
-15
-29
-44
-59
-74
-88
-104
-118
-133
30
28
13
-2
-18
-33
-48
-63
-79
-94
-109
-125
-140
35
27
11
-4
-20
-35
-51
-67
-82
-98
-113
-129
-145
40
26
10
-6
-22
-37
-53
-69
-85
-100
-116
-132
-148
WINDS GREATER
THAN 40 MPH HAVE
LITTLE ADDITIONAL
EFFECT
LITTLE DANGER
<5 hrs with dry skin
GREATEST HAZARD FROM
Greatest
hazard from false security
FALSE SECURITY
INCREASING DANGER
GREAT DANGER
Exposed flesh may freeze within 1 minute Exposed flesh may freeze within 30 sec.
Trenchfoot and Immersion foot may occur at any point on this chart.
COLD INJURY
PREVENTION
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COLD-
Keep clothing clean
Avoid overheating
Wear clothes loose and in layers
Keep clothing dry
Flight Operations
Winter Weather
• Temperature / Dew Point = Watch out for Fog
• Ice fog -25 F and colder
• Icing conditions
– Warm front over a cold air mass or land form
– Mountainous uplift
– +04 C to -20 C
• Flying or driving into visible moisture = surface
icing
Icing
**Aircraft Icing is the most hazardous condition associated with the cold**
Conditions for Icing:
• Temperatures between 32oF(0oC) and -4oF (-20oC)
• Visible Moisture (Clouds, Drizzle, Rain, Wet Snow)
• Rarely found at temps below -4oF (-20oC)
AR 95-1
• Aircraft will not be flown into known or forecast severe icing
• If flight is to be made into known moderate icing, aircraft must be
equipped with adequate operational deicing or anti-icing equipment.
Icing Intensities
• Trace
• Light
• Moderate
• Severe
Trace Icing
The trace category is used
when the rate of ice
accumulation is just slightly
greater than the rate of loss
due to sublimation. This
category of icing is not
hazardous. De-icing, antiicing equipment, or an
altitude change are not
necessary unless this
category is encountered for
one hour or more.
Light Icing
The light icing category
means that the rate of ice
accumulation may create a
problem if the aircraft
remains in this environment
for one hour or more.
Occasional use of de-icing
or anti-icing equipment is
necessary to remove or
prevent accumulation.
When prolonged flight in
this environment is likely, a
heading or altitude change
becomes necessary.
Moderate Icing
When the rate of ice
accumulation is so great that even
a short encounter can become
hazardous. The use of de-icing or
anti-icing equipment is necessary.
Often a heading or altitude
change is also required especially
if the aircraft remains in the
moderate icing environment for
more than a very short period.
This photo represents a moderate
icing condition.
Severe Icing
Icing is severe whenever
the rate of ice
accumulation is such that
de-icing or anti-icing
equipment cannot control
or reduce the hazard.
Typically an immediate
heading and/or altitude
change is necessary
Icing Types
• Rime Icing
• Clear Icing
• Mixed Icing
Rime Icing
Rime ice grows when
droplets rapidly freeze
upon striking an aircraft.
The rapid freezing traps
air and forms a brittle,
opaque, and milkycolored ice. Rime ice
grows into the air
stream from the forward
edges of wings and
other exposed parts of
the airframe.
Clear Icing
In clear ice formation, only a
small portion of the drop freezes
immediately while the remaining
unfrozen portion flows or smears
over the aircraft surface
gradually freezing. Since few air
bubbles are trapped during this
gradual process, the end result is
ice less opaque and denser than
rime ice that can appear either as
a thin smooth surface or as
rivulets, streaks, or bumps of
clear ice.
Mixed Icing
Due to variations in Liquid Water Content, temperature, and droplet
sizes, an airplane can encounter both rime and clear icing along its
flight path. Known as mixed
icing, this can appear as layers of
relatively clear and opaque ice
when examined from the side.
Mixed ice is similar to clear
ice in that it can spread over
more of the airframe's
surface and is more difficult
to remove than rime ice
Frequency and Occurrence
Rime icing is the most
frequently reported
icing.
The type of icing is
dependent on the
temperature, liquid
water content, and
other aircraftdependent variables.
Frequency and Occurrence
Temperature can be a good indicator for diagnosing the type of
icing expected. The relationship between temperature and icing
type that is typically used is outlined in the following table:
Clear 0° C to -10° C
Mixed -10° C to -15° C
Rime -15° C to - 40° C
These relationships are meant to be used as general guidance
Flight Techniques
Before starting engine(s). Check all controls for full travel and freedom of
movement.
Starting engine(s). If applicable, start engines with the propellers feathered to
prevent the tires from sliding.
Warm-up and ground operation. If so equipped, use the brake de-ice, as
required, to thaw frozen brakes. Allow adequate warm-up time for gyro
instruments.
Taxiing. Use an outside observer, if available, to confirm that the wheels are
turning and not sliding.
• When possible, avoid taxiing through snow and slush.
• Do not set the parking brake when the aircraft is stopped.
• Use chocks or sandbags and the brake de-ice, if installed.
Flight Techniques
Before takeoff.
• Activate anti-icing systems, allowing sufficient time for the equipment to
become effective.
• If the possibility of ice accumulation on flying surfaces exists, do not attempt
to take off.
• Accumulations of slush/snow on the runway greatly increase the takeoff
distance and should be taken into consideration during planning.
Takeoff.
• Procedures are the same as for a normal takeoff, except for a possible
decrease in aircraft performance caused by the use of the anti-icing/de-icing
equipment.
• Before starting takeoff roll, check all controls for full travel and freedom of
movement.
• Smoothly apply power to avoid asymmetrical thrust conditions.
Flight Techniques
During flight. Refer to the aircraft operator's manual for after-takeoff procedures.
• Climb at a higher-than-normal airspeed to prevent ice accumulation on
unprotected surfaces.
• Allow ice to accumulate according to the aircraft operator’s manual before
activating the surface deicing equipment.
• Higher-than-normal stall speeds should be expected and,
• As ice accumulates the stall warning system may become unreliable.
Landing. Landings on icy runways should be made only when necessary.
(Refer to the aircraft operator’s manual for any limitations and special procedures.)
• To avoid impairing visibility, reverse power should be used with caution
when landing on a runway covered with snow or standing water.
Before leaving the aircraft. Refer to the aircraft operator's manual for procedures.
Summary
• Cold Injury Factors
• Cold Injury Prevention “COLD”
• Icing Conditions
• Flight Techniques
QUESTIONS?