Scanner Course #5/Mission Pilot Course #2
Aviation Weather for Scanners and
Observers
Wake Turbulence
High Altitude and Terrain
Considerations
Minnesota Wing Aircrew Training:
Tasks P-2020, P-2023, P-2024 (scanner)
P-2008, P-2009, P-2010, P-2011 (observer)
Scanner Course #5/Mission Pilot Course #2
Aviation Weather
Scanner Course #5/Mission Pilot Course #2
Weather
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The most important aspect of weather is
its impact on flight conditions
Safety is paramount
Navigation — Visual verses Instruments
Effects on Search
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Prevailing visibility
Search visibility
Search patterns and altitudes
Information — National Weather Service,
Flight Service Stations, Pilot Reports
Scanner Course #5/Mission Pilot Course #2
Weather — Circulation
Scanner Course #5/Mission Pilot Course #2
Weather — Circulation
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The earth rotates
Air moving north is
pulled toward the east
This builds a high
pressure belt about 30
degrees latitude
The northerly air flow
cools and starts
southward
These large circulations
are responsible for
mixing the air and most
weather
Scanner Course #5/Mission Pilot Course #2
Circulation Around a High
H
Scanner Course #5/Mission Pilot Course #2
Circulation Around a Low
L
Scanner Course #5/Mission Pilot Course #2
Upward Convection Currents
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Terrain which heats up creates updrafts
Updrafts tend to keep you from
descending
Normally where there are updrafts there
are also downdrafts
EFFECT OF CONVECTION CURRENTS
NORMAL GLIDE PATH
ROCKY TERRAIN
PLOUGHED GROUND
PAVED ROAD
Scanner Course #5/Mission Pilot Course #2
Downward Convection Currents
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Terrain which remains cool up creates
downdrafts
Downdrafts cause you to descend
GLIDE PATH DUE TO CONVECTION CURRENTS
NORMAL GLIDE PATH
RIVER
GROWING FIELDS
LANDING FIELD
Scanner Course #5/Mission Pilot Course #2
Terms
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As altitude increases the temperature
decreases at a fairly uniform rate of 3.6
degrees F per 1000 feet; this is known as
lapse rate
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Use this on hot days to determine how high you
should climb to get to a comfortable temperature
At some altitude the air temperature reaches
the freezing temperature of water; the
freezing level
Scanner Course #5/Mission Pilot Course #2
Icing
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Frost
Snow
Icing
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Effects of icing
Airframe
Carburetor
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Lift
Decreases
Drag
Increases
Thrust
Decreases
Weight
Increases
May form in clear air at
temperatures substantially
above freezing
Rime ice is rougher
Glaze ice is clearer
Scanner Course #5/Mission Pilot Course #2
Warm Front
WARM AIR
Cirrus
Cirrostratus
Altostratus
COLD AIR
Nimbostratus
St Louis
Indianapolis
Columbus
Pittsburgh
Scanner Course #5/Mission Pilot Course #2
Characteristics of Warm
Stable Air Masses
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Stratus and Stratocumulus clouds
Generally low ceilings
Poor visibility (fog, haze, smoke and dust
held at low levels)
Smooth, stable air with little or no
turbulence
Slow steady precipitation or drizzle
Scanner Course #5/Mission Pilot Course #2
Cold Front
COLD AIR
St Louis
Cumulonimbus
Indianapolis
WARM AIR
Columbus
Pittsburgh
Scanner Course #5/Mission Pilot Course #2
Characteristics of Cold
Unstable Air Masses
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Cumulus or cumulonimbus clouds
Unlimited ceilings (except during
precipitation)
Excellent visibility (except during
precipitation)
Unstable air resulting in pronounced
turbulence in lower levels
Occasional local thunderstorms or
showers - hail, sleet, snow flurries
Scanner Course #5/Mission Pilot Course #2
Occluded Front
Cirrus
Cumulonimbus
WARM AIR
Nimbostratus
Cirrostratus
Altostratus
COLD AIR
COLD AIR
St Louis
Indianapolis
Columbus
Pittsburgh
Scanner Course #5/Mission Pilot Course #2
Reduced Visibility
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Under almost all circumstances, VFR
daytime flight requires:
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At least three miles visibility
When clouds cover more than one-half the
sky, cloud bases must be no lower than 1,000
ft. AGL
Search aircraft must usually remain at least
500 ft. below the cloud deck
There are exceptions: ask your PIC
Scanner Course #5/Mission Pilot Course #2
Reduced Visibility
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Fog
Haze
Snow
White out
Blowing dust
Affected by sun angle and direction
Aircrew must increase vigilance during these
conditions
Scanner Course #5/Mission Pilot Course #2
Turbulence
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Can reduce scanning
effectiveness
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Increases fatigue
Interferes with scan Planning
flight around high terrain
requires special care
Plan flights around high
terrain carefully
Wind currents on the
downwind side can be very
strong
Ridges and peaks should be
cleared by at least 2000 feet
Flight Path
2000 ft.
Wind
Scanner Course #5/Mission Pilot Course #2
Flight Precautions
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Each member of the aircrew must be
vigilant during all phases of flight
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Characterize visibility in the search
area to establish the proper scanning
range
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Assign each an area to watch
May be different than assumed
Visibility conditions or turbulence may
increase fatigue
Scanner Course #5/Mission Pilot Course #2
Wind Shear
- Appears as a change in wind
direction and/or speed within a very
short distance in the atmosphere
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Thunderstorms
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Fronts - wind
shear may
advance as far
as 15 nm
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Air flow around
obstacles
Windward
Scanner Course #5/Mission Pilot Course #2
Wind Shear
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Two potentially hazardous
situations, dangerous mainly
during landing:
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Tailwind turns calm or to a headwind
Headwind turns calm or to a tailwind
Pilot must adjust quickly
Scanner Course #5/Mission Pilot Course #2
Wake turbulence
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Caused by aircraft moving through the air
generating lift (proportional to weight)
Settle 500 to 800 feet below the flight
path
Drift out slowly (5 mph) on the ground
Takeoff before, land after other aircraft
Scanner Course #5/Mission Pilot Course #2
Wake turbulence
Scanner Course #5/Mission Pilot Course #2
Weather — Thunderstorms
Remain clear of thunderstorm activity by at
least 20 miles
Cumulus Stage
Mature Stage
Dissipating Stage
Scanner Course #5/Mission Pilot Course #2
High Altitude and
Terrain Considerations
Scanner Course #5/Mission Pilot Course #2
Atmospheric Pressure
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A barometer is used to register
changes in pressure; measured in
inches of mercury
Standard sea-level pressure and
temperature:
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29.92 inches of mercury
59 degrees F (15 degrees C)
A change of 1000 feet in elevation
makes a change of about one inch
To correct for local elevation, set
altimeter to latest reading
(ATIS/AWOS/ASOS/FSS) or enter
field elevation
18,000 ft = 7.5 lbs per sq in
10,000 ft = 10 lbs per sq in
Sea Level = 15 lbs per sq in
Scanner Course #5/Mission Pilot Course #2
Density Altitude
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Three factors:
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Pressure
Temperature
Humidity
Altitude and pressure
combined to determine
pressure altitude
Add non-standard
temperature to get
density altitude
Pilots calculate (next
slides) or can get on
ASOS
– Affects takeoff,
climb, true air
speed
Scanner Course #5/Mission Pilot Course #2
Flight Computer
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Circular slide rule
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Density altitude
Nautical to statute
miles
True airspeed
Other stuff
Scanner Course #5/Mission Pilot Course #2
Aircraft Performance
Density altitude and aircraft weight
have a tremendous effect on aircraft
performance
 Both must be accurately calculated,
especially for mountain flying missions
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Scanner Course #5/Mission Pilot Course #2
Pressure vs. Performance
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As altitude increases pressure decreases; this
decrease can have a pronounced effect on
flight:
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Engine (hp) and prop are less efficient
Take off distance, climb rate, and landing distance
effected
Take off distance almost doubles with a 5000
foot elevation increase
Rate of climb slows with higher elevation
Landing distance increases with higher elevation
Higher Humidity, Heat or Height result in
reduced aircraft performance
Scanner Course #5/Mission Pilot Course #2
Effects of Density Altitude
Takeoff Roll at Sea Level
Takeoff Roll at 5,000 ft Density Altitude
Climb at LOWER Density Altitude
Climb at HIGHER Density Altitude
Scanner Course #5/Mission Pilot Course #2
Strategies
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Don’t fly at high elevation during the hottest
part of the day
Carefully calculate DA and weight
Reduce load:
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Less fuel
Crew of three instead of four
Less baggage
Remember “High to Low, Look out Below”
(update altimeter setting hourly)
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If you fly in the mountains, take the Mountain
Fury Course
Scanner Course #5/Mission Pilot Course #2
Flight Near Mountainous Terrain
Scanner Course #5/Mission Pilot Course #2
Flight Near Mountainous Terrain
Scanner Course #5/Mission Pilot Course #2
Flight Near Mountainous Terrain
Flight Path
2000 ft.
Wind
Scanner Course #5/Mission Pilot Course #2
Dehydration
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The loss of water through the skin, lungs and
kidneys never ceases
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Loss increases as the humidity drops with increasing
altitude
Symptoms are dryness of the tissues and
resulting irritation of the eyes, nose and throat
Minimize intake of coffee, tea, cola or cocoa
since they contain caffeine and other chemicals
Strategies
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Drink plenty of fluids
Increase air flow (vents and windows)
If the search objective allows, reduce temperature by
climbing to higher altitude
Scanner Course #5/Mission Pilot Course #2
Effects of Altitude on Crew
Member Performance
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Ear Block
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Sinus Block
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Congestion around the Eustachian tube makes pressure
equalization difficult
Can produce severe pain and a loss of hearing that can last from
several hours to several days (can rupture eardrum)
Sinus congestion makes pressure equalization difficult,
particularly during descent
Can produce severe pain
Hypoxia (Lack of oxygen to the brain)
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Loss of night vision as low as 5,000 feet
For most people altitudes above 12,000 feet result in a loss of
judgment , coordination, memory, and alertness
Normally not a concern for non-mountainous CAP operations
(usually below 12,000 MSL)
Body has no built-in warning system against hypoxia
Scanner Course #5/Mission Pilot Course #2
Strategies
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Ear Block
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Sinus Block
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Yawn, swallow, tense muscles in throat
Valsalva maneuver
Don’t fly if you’re not well
Medication usually not effective and has side
effects
Hypoxia
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Avoid smoking, alcohol and depressants
Supplemental oxygen