Transcript General Aviation Icing

General Aviation Icing
PA 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 A&I, AGI, IGI, ASC
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)
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 abovefreezing air below and the above-freezing air above
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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."
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.
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
AOPA Air Safety Foundation
Weather Accident Statistics
Most
Common
Problem
Most CAP
Pilots
Most CAP
Aircraft
•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%
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
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 -(a) 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;
(b) For any flight, runway lengths at airports of intended use, and the following
takeoff and landing distance information:
1) 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
2) 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.
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
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
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 won’t dislodge
– What would you do?
– Hypothetical PIC continues practice ILS approach
• Now what?
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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
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
Preparation to Cope with ASI Failure
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Pre-Flight Knowledge Areas
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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
Instrument Cross-Check
for Failed ASI
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
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
ASI Failure on Precision Approach
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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
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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"
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
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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"
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
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 Pilot’s 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.
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 A&I, 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
Aim High!
But Not On Final!