Mission Aircrew Course Chapter 6: Weather (August 2006) - PowerPoint PPT Presentation

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Mission Aircrew Course Chapter 6: Weather (August 2006)

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Title: CAP Observe Course s Author: Rich Simerson Description: Rev. 0, March 2004 Last modified by: Kathy Wolfe Created Date: 9/26/1994 3:23:44 PM – PowerPoint PPT presentation

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Title: Mission Aircrew Course Chapter 6: Weather (August 2006)


1
Mission Aircrew CourseChapter 6 Weather(August
2006)
2
Aircrew Tasks
  • P-2008 DISCUSS THE DANGERS OF ICING (O)
  • P-2009 DISCUSS THE DANGERS OF REDUCED VISIBILITY
    CONDITIONS (O)
  • P-2010 DISCUSS THE DANGERS OF WIND AND
    THUNDERSTORMS (O)
  • P-2023 DISCUSS HOW REDUCED VISIBILITY AND
    TURBULENCE EFFECT SEARCH OPERATIONS (S)

3
Objectives
  • Discuss how convection currents affect aircraft
    glide path. O 6.1.3
  • Discuss wind patterns around high- and
    low-pressure areas. O 6.1.5
  • Define freezing level and lapse rate
    O 6.2.1
  • Discuss airframe icing and its affect on aircraft
    performance. O 6.2.2
  • Discuss carburetor icing and its affect on
    aircraft performance. O 6.2.3

4
Objectives (cont)
  • Discuss the characteristics of cold, unstable air
    masses and warm, stable air masses. O 6.3
  • Concerning reduced visibility conditions, state
    the minimums for O 6.4
  • VFR visibility
  • Cloud bases when they cover one-half the sky
  • How far aircraft must remain below cloud cover
  • Discuss the dangers of windshear. O 6.6
  • Describe the stages of a typical thunderstorm
    and discuss the dangers of flying too close.
    O 6.7

5
Weather
  • The most important aspect of weather is its
    impact on flight conditions
  • Safety is paramount
  • Navigation Visual verses Instruments
  • Effects on Search
  • Prevailing visibility
  • Search visibility
  • Search patterns and altitudes
  • Information National Weather Service, Flight
    Service Stations, Flight Watch, PIREPs

6
Flight precautions
  • Each member of the aircrew must be vigilant
    during all phases of flight
  • Assign each an area to watch
  • Characterize visibility in the search area to
    establish the proper scanning range
  • May be different than assumed
  • Visibility conditions or turbulence may increase
    fatigue

7
Weather Circulation
8
Weather Circulation
  • 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

9
Upward Convection Currents
  • 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
10
Downward Convection Currents
  • Terrain which remains cool creates downdrafts
  • Downdrafts cause you to descend

11
Turbulence
  • Planning flight around high terrain requires
    special care
  • 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
12
Circulation Around a High
Air Sinks Moves Clockwise
13
Circulation Around a Low
L
Air Rises Moves Counter Clockwise
14
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15
LAPSE RATE
  • As altitude increases the temperature decreases
    at a fairly uniform rate of 3.6 degrees F per
    1000 (2.0 degrees C per 1000) feet this is known
    as lapse rate
  • 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

16
Icing
  • Frost
  • Snow
  • Icing
  • Airframe
  • (lift weight)
  • Carburetor

Drag
Lift
Increases
Decreases
W
eight
Thrust
Increases
Decreases
17
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18
  • The wing of a NASA Twin Otter after landing. This
    looks to be clear icing or perhaps mixed. Notice
    the runback well past the leading edge and on the
    underside of the wing.

19
  • The rectangular device on the windshield is the
    "hot plate", a plate of electrically heated glass
    which is mounted just ahead of the plastic
    windshield. When ice formation is especially bad,
    the only view forward is through the upper two-
    thirds of the plate, and the area around it
    becomes crusted with frozen runoff from the
    heated area.

20
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21
Carburetor Icing
  • Moisture in the air can condense, then freeze,
    blocking further flow of air and fuel to the
    engine.
  • Airplanes most vulnerable when operated in high
    humidity OR visible moisture with temperatures
    between 45F and 85F.
  • Most likely to form at low power settings such as
    in descents and approaches to landings.
  • Fuel injected engines are not vulnerable to
    carburetor icing.

22
Causes of Frontal Activity
COLD POLAR AIR
DRY AIR
TROPICAL MOIST AIR
23
Warm Front
dust/polutants
24
Cold Front
25
Occluded Front
26
Clouds
Altocumulus
27
Lenticular
28
Lenticular
29
Towering Cumulus
30
Mushroom Cloud
31
Reduced Visibility
  • Under almost all circumstances, VFR daytime
    flight requires
  • 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

32
Reduced Visibility
  • Fog
  • Haze
  • Snow
  • White out
  • Blowing dust
  • Affected by sun angle and direction
  • Aircrew must increase vigilance during these
    conditions

33
Wind Shear
  • Thunderstorms
  • Fronts - wind shear may advance as far as 15 nm
  • Air flow around obstacles

Windward
34
Wind Shear
  • Two potentially hazardous situations, dangerous
    mainly during landing
  • Tailwind turns calm or to a headwind
  • Headwind turns calm or to a tailwind
  • Critical conditions for potential low-level wind
    shear
  • Cold Front
  • After front passes
  • If moving 30kts or more, may exist below 5000 ft
    for up to 3 hours
  • Warm front
  • Before front passes
  • May exist below 5000 ft. for up to 6 hours
  • Danger passes once front passes airport
  • Pilot must adjust quickly

35
Weather Thunderstorms
Cumulus Stage
Mature Stage
Dissipating Stage
36
Lightning In Cloud (IC)
37
Cloud to Cloud (CC)
38
Flight Planning WX SourcesTelephone National
Weather Service
  • 1-800 WX Brief (1-800-992-7433)
  • Standard Briefing
  • METARS (updated as significant change has
    occurred)
  • Terminal Area Forecast (i.e. IND)
  • Good for 12 hours
  • 3 x per day
  • Area Forecast (entire state or area you
    designate)
  • Every 12 hours
  • Route of Flight

39
  • Winds Aloft
  • All altitudes
  • Notams
  • Current Airmets
  • Convective Sigmets
  • Cloud Tops (reported)
  • Pilot Reports (PIREPS)
  • High/Low Pressure Areas
  • Fronts

40
Flight Planning WX Sources Computer
  • AOPA.org
  • Weather
  • Satellite Images
  • Radar Imagery
  • Surface Wx Imagery
  • Upper Air Imagery
  • Textural Wx.

41
  • Weatherunderground.com
  • Temperature
  • Heat Index
  • Wind Chill
  • Radar
  • Dewpoint
  • Visibility
  • SPAM

42
  • Intellicast.com
  • Radar
  • Severe Weather
  • Satellite
  • Surface Analysis
  • Hurricane Watch
  • More Spam

43
  • NOAAs National Weather Center (adds.aviationweath
    er.noaa.gov)
  • Turbulence
  • Convection
  • Winds/Temps
  • Prog Charts
  • Metars
  • Tafs
  • Pireps

44
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45
Plain Language Interpretation of METAR
46
JOT Time 1240Z C-172 at Fl Level 2500. Reported
sky cover was overcast from 8000-10000 ft.
Occasional light chop. Scattered Virga Observed.
47
JOT reported at the same time 1245Z showed
surface weather winds from 190 at 4knots,
visibility was 10sm and CLEAR! Temperature was
23C and dewpoint 19C.
48
Radio Services
  • Flight Service Station (FSS)
  • Flight Watch (122.0)
  • Automatic Terminal Information Service(ATIS)
  • Transcribed weather broadcasts (TWEB)
  • Scheduled weather broadcasts
  • Fifteen minutes after the hour
  • Alerts, hourly weather, Advisory, Pilot Reports,
    Radar
  • Pilot Weather Reports (PIREP)

49
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