General Aviation Icing PA Wing Safety Days

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General Aviation IcingPA Wing Safety Days Fall
2006

• Capt William J. Doyle, Jr. Director of Standards
  and Evaluation, Pennsylvania Wing
• Check Pilot / Instructor-Pilot, FAA Safety
  Counselor
• CFI AI, AGI, IGI, ASC

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Lesson Plan

• What is icing?
• How big a problem is icing?
• Some icing scenarios
• Carburetor Icing (Civilian Cessna 182Q)
• Rime Icing (Civilian Cherokee 180)
• Clear Icing (Civilian Cessna 182R)
• Visible Precipitation (Civilian Cirrus SR20)

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Icing Terms

• Icing occurs when liquid moisture comes into
  contact with an object that is at a
  below-freezing temperature.
• Step outside on any bitter cold winter morning.
• Using your moist, above-freezing tongue, lick the
  below-freezing, metal street post. (Don't try
  this alone)
• Two possible sources of liquid moisture are the
  above-freezing air below and the above-freezing
  air above
• Aircraft icing classified as "clear," "rime," or
  "mixed."
• If source of liquid moisture is the air below,
  rime ice will form.
• If liquid moisture falling as rain from above,
  clear ice will form.
• If attacking from both directions (e.g. as in a
  cumulus cloud) the icing will be mixed.
• "Rime" is shorthand for "bad"
• "clear" is shorthand for "really bad."

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Icing Terms (continued)

• Icing From Above (freezing rain) requires a
  strong temperature inversion.
• Usually with an advancing warm front
• Warm air is elevated as it advances over the
  underlying cooler air
• it expands and cools
• Water vapor condenses into rain in the higher
  above-melting air, falls into the lower,
  below-melting air,
• locates your airplane and turns it into a flying
  popsicle
• Supercooled raindrops are huge in comparison to
  the supercooled water droplets encountered flying
  through a cloud
• Supercooled raindrops generate a much greater
  volume of ice
• when your plane runs into them.
• The larger drops of liquid readily spread before
  they freeze
• that is why the ice is "clear"
• For GA pilots, the appropriate precaution for
  freezing rain is to avoid it at all costs.

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En Route Icing Precautions

• Be alert for first indication of ice
• Movement of air across skin surface heats skin,
  tends to sweep liquid moisture away before it
  contacts aircraft skin
• First indications of icing occur in areas of dead
  air
• base of windshield
• area around OAT probe
• leading edge of wing
• In those locations, air does not flow smoothly
  across skin surface
• keeps the skin surface relatively cool
• prevents airflow from sweeping away liquid
  moisture

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AOPA Air Safety Foundation Weather Accident
Statistics
Most Common Problem
Most CAP Aircraft
Most CAP Pilots

• 12 of all weather accidents were due to icing.
  Of those
• Induction icing (carburetor ice) leading factor
  in 52
• Structural icing leading factor in 40

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AOPA Air Safety Foundation on Carburetor Icing

• At the first indication of carburetor ice
• Apply full carburetor heat
• LEAVE IT ON
• The engine may run rougher as the ice melts and
  goes through it
• but it will smooth out again
• When the engine runs smoothly
• Turn off the carburetor heat
• If you shut off the carburetor heat prematurely
• the engine will build more ice
• and probably quit because of air starvation

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Review of FAR 91.103

• FAR 91.103 - Preflight action.
• Each pilot in command shall, before beginning a
  flight, become familiar with all available
  information concerning that flight. This
  information must include --
• For a flight under IFR or a flight not in the
  vicinity of an airport, weather reports and
  forecasts, fuel requirements, alternatives
  available if the planned flight cannot be
  completed, and any known traffic delays of which
  the pilot in command has been advised by ATC
• For any flight, runway lengths at airports of
  intended use, and the following takeoff and
  landing distance information
• For civil aircraft for which an approved Airplane
  or Rotorcraft Flight Manual containing takeoff
  and landing distance data is required, the
  takeoff and landing distance data contained
  therein and
• For civil aircraft other than those specified in
  paragraph (b)(1) of this section, other reliable
  information appropriate to the aircraft, relating
  to aircraft performance under expected values of
  airport elevation and runway slope, aircraft
  gross weight, and wind and temperature.

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Hypothetical Carburetor Ice Scenario

• Engine roughness at night in IMC
• What would you do?
• Hypothetical PIC applies carburetor heat
• The roughness worsens
• What would you do?
• Hypothetical PIC turns off the carburetor heat
• Now what?
• What would you do?
• Hypothetical PIC calls ATC and reports situation
• ATC offers vectors for an approach and
  precautionary landing at non-towered field with
  LOC approach

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Hypothetical Rime Ice Scenario

• Icing is in forecast at 5,000 feet
• What would you do?
• Hypothetical PIC files IFR flight plan with
  comments about no altitudes above 3,000 feet due
  to ice
• Departure clears hypothetical pilot to 5,000 feet
• What would you do?
• Hypothetical PIC tries to negotiate clearance but
  ultimately climbs to 5,000 feet
• Rime ice immediately begins to form. Now what?
• What would you do?
• Hypothetical PIC gets immediate descent to 3,000
  feet
• Rime ice sticks until out of clouds at 1,700 feet

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Hypothetical Clear Ice Scenario

• Windshield and leading edges ice over in day VFR
• What would you do?
• Hypothetical PIC continues practice ILS approach
• The windshield ice wont dislodge
• What would you do?
• Hypothetical PIC continues practice ILS approach
• Now what?
• What would you do?
• Hypothetical PIC flies ILS below DH
• Hypothetical PIC uses side windows for landing
• After sitting for an hour on ramp, ice still in
  place

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ASI Failure Scenario in Visible Precip

• ILS approach in IMC (clouds and rain)
• What would you do?
• Hypothetical PIC flies ILS approach without pitot
  heat
• The airspeed indicator (ASI) goes to zero
• What would you do?
• Hypothetical PIC pitches down about 15º ? 20º
• Now what?
• What would you do?
• Hypothetical PIC cross-checked other instruments
• Hypothetical PIC flew approach to successful
  outcome

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Preparation to Cope with ASI Failure

• Pre-Flight Knowledge Areas
• Understand flight instrument cross-check and
  correlation.
• Understand Flight Instrument Perspectives of an
  ASI Failure.
• Know power settings for various flight profiles.
• In-Flight Situational Awareness
• Periodically correlate ASI airspeed with GPS
  groundspeed for a given flight regime or
  direction of flight.
• Know wind direction and velocity for each flight
  leg
• Get frequent updates from Flight Watch, ATIS,
  ASOS, and ATC
• Activate Pitot Heat at first sign of visible
  precipitation

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Instrument Cross-Check for Failed ASI
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ASI Failure Enroute

• Cross-check Flight Instruments to verify level
  flight attitude
• Attitude Indicator (AI) miniature airplane on
  horizon
• Altimeter (ALT) altitude is constant at assigned
  altitude
• Vertical Speed Indicator (VSI) needle on zero
• When nearing destination airport
• Reduce power setting to a descent profile.
• Cross-check using groundspeed indicated on GPS
• Extend flaps to approach setting

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ASI Failure on Vectors to Approach

• Reduce power to setting to obtain an airspeed of
  90 to 120 Kts, depending on aircraft
• Cross-check using the groundspeed indicated on
  the GPS
• When slowed and stabilized, extend flaps to
  approach setting
• Cross-check Flight Instruments to verify level
  flight attitude
• AI miniature airplane on the horizon
• ALT altitude is constant at assigned altitude
• VSI needle on zero

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ASI Failure on Precision Approach

• When established, reduce power to obtain 90-100
  Kts
• Cross-check using the groundspeed indicated on
  GPS
• Check VSI for 500 - 600 FPM rate of descent
• Intercept Glideslope (GS) and follow GS prompts
  on HSI
• If above Glideslope
• Reduce power slightly (1" - 2" MP or 100 RPM)
• Pitch down slightly to acquire GS
• When GS acquired, adjust power and pitch to
  maintain GS
• If below Glideslope
• Increase power slightly (1" - 2" MP or 100 RPM)
• Pitch up slightly to acquire GS
• When GS acquired, adjust power and pitch to
  maintain GS
• At Decision Height (DH) and airport complex in
  sight
• Reduce power to landing power setting
• Extend flaps to full
• Pitch for 500 FPM rate of descent on VSI
• Pre-landing checklist (GUMP)
• Gradually reduce power to idle when runway is
  "made"

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ASI Failure on Non-Precision Approach

• When established, reduce power to obtain 90-100
  Kts
• At Final Approach Fix (FAF)
• Start time
• Check VSI for 700 - 750 FPM rate of descent
• Level off at Minimum Descent Altitude (MDA)
• If above MDA
• Reduce power slightly (1" - 2" MP or 100 RPM)
• Pitch down slightly to acquire MDA
• When MDA acquired, adjust power and pitch to
  maintain MDA
• If below MDA
• Increase power slightly (1" - 2" MP or 100 RPM)
• Pitch up slightly to acquire MDA
• When MDA acquired, adjust power and pitch to
  maintain MDA
• At Missed Approach Point (MAP) and airport
  complex in sight
• Reduce power to landing power setting
• Extend flaps to full
• Pitch for 500 FPM rate of descent on VSI
• Pre-landing checklist (GUMP)
• Gradually reduce power to idle when runway is
  "made"

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Summary

• Get a thorough weather briefing
• Thoroughly review Winds and Temperatures aloft
• Understand the lapse rate and how it relates to
  your planned altitude and route of flight
• PIC needs to
• Apply pitot heat at first sign of visible
  precipitation
• Apply carb heat at first sign of engine roughness
• Keep carb heat on until engine runs smooth
• Determine power settings for various flight
  regimes
• MP settings and RPM settings

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Credits and Citations

• Doyle, William J., Jr., Emergencies Airspeed
  Indicator Failure, Cirrus SR20 Transition
  Training, January 2003.
• Puddy, R. Scott, Icing Taking Adequate
  Precautions, AVweb, July 2002.
• http//www.avweb.com/news/airman/181876-1.html
• Puddy, R. Scott, Flying Into Known Icing Is It
  Legal?, AVweb, July 2002.
• http//www.avweb.com/news/airman/181877-1.html
• FAA General Aviation Pilots Guide to Preflight
  Weather Planning, Weather Self-Briefings, and
  Weather Decision Making.
• AOPA-ASF Aircraft Icing, Pamphlet SA11 .
• AOPA-ASF Aircraft Deicing and Anti-Icing
  Equipment, Pamphlet SA22.

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About the Presenter

• Aviator
• Commercial, Instrument, ASEL AMEL
• 2,600 hours total time 500 hours TAA 500 hours
  KFC 150 600 hours Garmin 430
• Instructor
• CFI AI, AGI, IGI, ASC
• 1,200 hours as CFI
• Cessna FITS Course and CFAI Course
• Civil Air Patrol
• Instructor-Pilot and Check-Pilot
• PA Wing Director of Standards Evaluation
• Technologist Teacher
• Director of Technical Services, Hatboro-Horsham
  School District
• Computer Science Instructor, La Salle University
• Author
• Two books on electronic spreadsheets, with a
  Russian translation
• Self-study manuscript on computer concepts for
  nurses
• Articles on gear up landings and fuel management
  published by FAA

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Aim High!But Not On Final!