Download - 1 Icing Two kinds: Induction and Structural Induction Icing: Icing in the power plant –Carburetor Icing Air is cooled with adiabatic expansion andendothermic.

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Icing• Two kinds: Induction and Structural

• Induction Icing: Icing in the power plant– Carburetor Icing

• Air is cooled with adiabatic expansion andendothermic evaporation of the fuel.

• Cooled below 0oC and Ice forms• Carburetor icing is 51% of all icing accidents• Can occur in SKC with OAT well above freezing• Check your POH for when carburetor heat is needed• Carb Heat reduces power, but is better than no power

– Jet Engine: Can develop ice in taxi, takeoff, & climb

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Icing• Structural Icing: Icing on the Airframe(The

outside of the airplane)–Skin temperature is 0oC or less–Decrease lift efficiency of the wings–Clogs the pitot-static system–Bad altitude, VSI, and KIAS due to

clogged Pitot–Adds weight to plane: may be several

hundred pounds of ice.

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Icing• Structural Icing

– Types of ice protection• Anti-icing: prevents ice from forming eg.

Heated wing edges• De-icing: Removes ice after it has formed eg.

Inflatable wing boots– Ground Icing: Occurs on the ground

• Usually from FZRA for FZDZ or SN• Can even happen to hangared planes on taxi• Do not assume takeoff roll will knock of ice!!• Remove all ice, snow and frost before takeoff• If it is still accumulating don’t take off!!!

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Icing• Structural Icing

–An 1/8 inch coating of ice can reduce lift by 30% and increase drag by 40%.

–A hard frost can increase stalling speed by 5 to 10%

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Icing• Observing and Reporting Structural Icing• Three types of ice: clear, rime, & mixed.

– Rime Ice: • Forms on surfaces by small droplets trapping air bubbles

usually -15oC• Usually white or opaque milky color

– Clear Ice:• Forms between 0oC and -5oC• Maybe translucent or a glaze• Heavy and Hard• Adheres strongly to the aircraft• Disrupts airflow over the wing

– Mixed Ice: forms from -5oC to -15oC

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Icing• Observing and Reporting Structural Icing

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Icing PiReps• AIZ UA /OV SHY321028 /TM 1609 /FL160 /TP AC68 /SK SKC /WX FV99SM /TA

M09 /WV 33045KT /RM SMTH • IKK UA /OV IKK360012 /TM 1815 /FL035 /TP C210 /SK SKC /TA M02 /TB MOD • DEC UA /OV DEC /TM 1832 /FLUNKN /TP P28A /SK FEW-SCT052 /WX

FV20SM /TB LGT /RM UPDRAFTS OF 100FT PER MIN • SGF UA /OV SGF360015 /TM 2238 /FL350 /TP WW24 /SK SKC /WV 33879KT /TB

INTMT-CONT LGT CHOP • IRK UA /OV IRK090020/TM 2336/FL230/TP C425/TA M23/IC LGT-MOD RIME/RM

FM ZKC • IRK UA /OV IRK240040/TM 2353/FL220/TP B737/TA M19/IC LGT MX 190-220/RM

FM ZKC • MCI UA /OV BQS /TM 0048 /FLUNKN /TP B717 /TA M02 /IC TRACE RIME 150-

190 • STL UA /OV STL326050/TM 0107/FL170/TP MD83/TA M15/IC LGT RIME 200-

170/RM BLW CLDS AT 160-FM ZKC • STL UA /OV STL326055/TM 0158/FL150/TP E135/TA UNKN/IC NEG 240-150/RM

FM ZKC • FAM UA /OV FAM030025/TM 0252/FL210/TP A320/TA M19/IC LGT RIME/RM FM

ZKC

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Icing PiReps

• FAM UA /OV FAM030025/TM 0252/FL210/TP A320/TA M19/IC LGT RIME/RM FM ZKC

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Microscale Icing Processes

• 3 Factors: Temperature, Droplet size, Liquid Water Conent

• Temperature:– Clear: 0oC to -5oC

– Clear or Mixed: -5oC to -10oC

– Mixed or Rime:-10oC to -15oC

– Rime: -15oC to -20oC

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Microscale Icing Processes• Liquid Water Content LWC

– Icing is rapid with high LWC– Icing is slow with low LWC– LWC is greater with warmer(lower) cloud

bases– LWC is less with colder(higher)

cloud bases– LWC can vary within a single cloud– Cumulus usually have higher LWC– Non-Convectivie Cirrus is usually low LWC

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Microscale Icing Processes• Droplet Size

– Super-cooled Large Droplets: SLD– Maybe below freezing– > .04mm in diameter– Rain is about 5mm in diameter– SLD forms by

• Collision/coalescence• Warm layer processes: snow falls into a warm

layer(>0oC) melt and then fall into a cold layer. This happens on a warm front frontal zone.

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Minimizing Icing Encounters• Droplet Size

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Minimizing Icing Encounters• See the lowest freezing level chart at:• http://adds.aviationweather.gov/icing/frzg_nav.php

• Consult PiReps, Metars and forecasts

• Consult a Sounding or Skew-T at

• http://weather.uwyo.edu/upperair/sounding.html

• (Use Gif: to 10mb and click on station)

• or• http://twister.sbs.ohio-state.edu/main.php?pageloc=upperair

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http://adds.aviationweather.gov/icing/frzg_nav.php

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Prevent Icing Crashes!!!

1. Prepare: Study Available Wx Info

2. Observe: Look at your plane and outside

3. Take Control: Feel your planes response

to control inputs frequently

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Minimizing Icing Encounters– f

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