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Authored by Rich Simerson Revised 01-Apr-2010 Modified by Lt Colonel Fred Blundell TX-129 Fort Worth Senior Squadron For Local Training Rev 5.0 04-Jan-2014 1
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2 This Training Slide Show is a project undertaken by Lt Colonel Fred Blundell of the TX-129 Fort Worth Senior Squadron, Fort Worth, TX for local use to assist those CAP Members interested in advancing their skills. The information contained herein is for CAP Member’s personal use and is not intended to replace or be a substitute for any of the CAP National Training Programs. Users should review the presentation’s Revision Number at the end of each file name to ensure that they have the most current publication.
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Objectives Discuss how convection currents affect aircraft glide path. Discuss wind patterns around high and low-pressure areas. Define “freezing level” and “lapse rate” Discuss airframe icing and its affect on aircraft performance. Discuss carburetor icing and its affect on aircraft performance. 3
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Objectives (continued) Discuss the characteristics of cold, unstable air masses and warm, stable air masses. Concerning reduced visibility conditions, state the minimums for: VFR visibility Cloud bases when they cover one-half the sky How far aircraft must remain below cloud cover Discuss the dangers of wind shear. Describe the ‘stages’ of a typical thunderstorm and discuss the dangers of flying too close. 4
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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, PIREP’s 5
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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 6
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Weather — Circulation 7
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Weather — Circulation (Continued) 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 8
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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 9 ROCKY TERRAIN PLOUGHED GROUND PAVED ROAD NORMAL GLIDE PATH EFFECT OF CONVECTION CURRENTS
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Downward Convection Currents Terrain which remains cool creates downdrafts Downdrafts cause you to descend 10
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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 11 Wind Flight Path 2000 ft.
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Circulation Around a High 12 H Air Sinks Moves Clockwise
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Circulation Around a Low 13 L Air Rises Moves Counter Clockwise
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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 15
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Icing Frost Snow Icing Airframe (lift & weight) (lift & weight) Carburetor 16 Lift Thrust Decreases Weight Increases Decreases Drag Increases Rime ice is rougher Glaze ice is clearer
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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. 18 Icing
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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. 19 Icing
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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. 21
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Causes of Frontal Activity 22 DRY AIR COLD POLAR AIR TROPICAL MOIST AIR
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Warm Front 23 St LouisIndianapolisColumbusPittsburgh Nimbostratus Altostratus Cirrostratus Cirrus WARM AIR COLD AIR dust/polutants
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Cold Front 24 St LouisIndianapolisColumbusPittsburgh COLD AIR WARM AIR Cumulonimbus
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Occluded Front 25 St LouisIndianapolisColumbusPittsburgh COLD AIR WARM AIR COLD AIR Cumulonimbus Nimbostratus Altostratus Cirrostratus Cirrus
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Clouds 26 Altocumulus
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Lenticular 27 Clouds
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Lenticular 28 Clouds
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Towering Cumulus 29 Clouds
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Mushroom 30 Clouds
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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 31
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Reduced Visibility (CONTINUED) Fog Haze Snow White out Blowing dust Affected by sun angle and direction Aircrew must increase vigilance during these conditions 32
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Wind Shear Thunderstorms Fronts - wind shear may advance as far as 15 nm Air flow around obstacles 33 Windward
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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 34
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Weather Thunderstorms 35 Cumulus StageMature StageDissipating Stage
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Lightning In-Cloud (IC) 36
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Cloud-to-Cloud (CC) 37
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Flight Planning WX Sources Telephone National Weather Service 38 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 hoursGood for 12 hours 3 x per day3 x per day –Area Forecast (entire state or area you designate) Every 12 hoursEvery 12 hours Route of FlightRoute of Flight
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Flight Planning WX Sources Telephone National Weather Service Winds Aloft All altitudes All altitudes Notams Notams Current Airmets Convective Sigmets Cloud Tops (reported) Pilot Reports (PIREPS) High/Low Pressure Areas Fronts 39
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Flight Planning Computer WX Sources AOPA.org Weather Satellite Images Radar Imagery Surface Wx Imagery Upper Air Imagery Textural WX 40
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Flight Planning Computer WX Sources (Continued) Weatherunderground.com Temperature Heat Index Wind Chill Radar Dew point Visibility 41
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Flight Planning Computer WX Sources (Continued) Intellicast.com Radar Severe Weather Satellite Surface Analysis Hurricane Watch More Spam 42
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Flight Planning Computer WX Sources (Continued) NOAA’s National Weather Center (adds.aviationweather.noaa.gov) Turbulence Convection Winds/Temps Prog Charts Metars Tafs Pireps 43
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45 Plain Language Interpretation of METAR
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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
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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 dew point 19C
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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) 48
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Questions? 50 Always Think Safety!
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