Transcript Winter Flying

Winter Flying
By Harry Hayon and Steve Morley
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Contents
• Introduction
• Types of Icing
• Atmospheric Conditions
• Break
• Steve’s Experiences
• Flight Preparation
• In-Flight Actions
• Summary
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Introduction
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Structural Icing
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Structural Icing
Rime Ice is rough and opaque, formed by supercooled drops
rapidly freezing on impact. Often "horns" or protrusions are
formed and project into the airflow.
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Structural Icing
Clear ice is often clear and smooth. Supercooled water
droplets, or freezing rain, strike a surface but do not freeze
instantly. Forming mostly along an aerofoil's stagnation point, it
generally conforms to the shape of the aerofoil.
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Structural Icing
Mixed ice is a combination of clear and rime ice. It is the most common type of structural icing due to the
different size of water droplets found in clouds.
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Induction System Icing
There are two kinds of induction
system icing: carburettor icing,
which affects engines with
carburettors only, and air intake
blockage, which affect aircraft
with, and without a carburettors.
Induction icing accidents top
the charts as the number one
cause of icing accidents,
comprising a considerable 52%!
Video
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Fuel Icing
Less common is fuel icing which is the result of water, held in suspension in the fuel,
precipitating and freezing in the induction piping, especially in the elbows formed by bends.
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Instrument Icing
Pitot heat should be used wherever appropriate in the winter. Be aware that radio signals may
be disrupted in icing conditions.
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Atmospheric Conditions
Icing and Cloud Types
All clouds and fog at subfreezing temperatures have icing potential. However, drop size, drop
distribution, and aerodynamic effects of the aircraft influence ice formation. Ice may not form
even though the potential exists.
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Atmospheric Conditions
Icing and Cloud Types
Altostratus
Cumulonimbus
Heaviest icing usually will be found at or slightly above the freezing level where temperatures
are never more than a few degrees below freezing. In layer type clouds, continuous icing
conditions are rarely found to be more than 5,000 feet above the freezing level, and usually are
two or three thousand feet thick.
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Atmospheric Conditions
Fronts
Freezing rain with a warm front (top) and a cold front (bottom). Rainfalls through warm air aloft
into subfreezing cold air near the ground. The rain becomes supercooled and freezes on
impact.
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Atmospheric Conditions
Terrain
Icing is more probable and more hazardous in mountainous regions than over other terrain.
Mountain ranges cause rapid upward air motions on the windward side, and these vertical
currents support large water drops.
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Atmospheric Conditions
Ground Icing
Frost, ice pellets, frozen rain, or snow may accumulate on parked aircraft. Pilots should remove
all frost and ice from aerofoils prior to take-off. Frost forms near the surface primarily in clear,
stable air and with light winds - conditions which in all other respects make weather ideal for
flying.
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Atmospheric Conditions
Strategy – So how do I apply this knowledge?
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Where are the fronts?
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Where are the fronts moving?
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Where are the cloud tops?
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Where are the cloud bases?
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What Alternate routes are
available?
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What are the escape routes?
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Break
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Steve’s Experiences
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Flight Preparation
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Check all equipment is present (pitot covers,
static vent plugs, control surface locks etc)
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Some engines may require a winter cooling
restrictor
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Engine oil may need to be changed
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Some aircraft require the addition of Iso-Propyl
alcohol in the fuel
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Ensure the engine crankcase oil breather pipes
are clear and free from deposits
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Flight Preparation
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Check the cabin heater/ demister is working
properly before you really need it
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Spot type carbon-monoxide detectors only have
a limited life once unwrapped – always ensure
it’s in date, it could save your life!
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Drain the Pitot-Static system if applicable
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Check that the pitot heater really is warming the pitot head
– but don't burn your hand (use the back of it) or flatten the
battery.
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Flight Preparation
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Ensure the battery is in good condition and well
charged
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Check control cables and adjust if necessary
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Check all airframe and prop de-icing systems
are operating properly
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Check wheel fairings are clear of mud and
debris
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Check tyre pressures are sufficient
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Flight Preparation
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Carry a cloth for demisting
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Dress sensibly, the heater may fail or you may
have to make a forced landing at some point
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Ensure the aircraft is swept clear of all ice, frost
and snow, even a small amount will degrade
performance significantly!
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The best way to remove snow from wings is
using a broom or brush
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Ensure control surface hinges, vents etc are not
contaminated
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Do not rely on the snow blowing off on takeoff!
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In-Flight – Departure
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Exercise caution when manoeuvring near areas
where obstacles may be covered by snow
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Check heater/ defrost early on
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Taxy slowly
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Allow gyro’s adequate time to spin up
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Consider using “soft field” takeoff technique
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Ensure no carburettor ice is present prior to
takeoff!
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In-Flight – Enroute
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After take-off cycle the gear
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Monitor conditions with a FIS or VOLMET
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Monitor engine RPM or MAP for indications of
carburettor icing and apply full carb heat
periodically
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If ice is present whilst using carb heat an
additional decrease in RPM/ MAP may occur,
keep carb heat set on hot whilst the ice clears
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If the aircraft is fitted with de-icing boots, its
good to cycle them from time to time to avoid
system valves from sticking
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In-Flight – Enroute
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Airframe icing is most frequently encountered in cumulous and cumulonimbus type clouds (CU/CB)
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If you fly in the cloud tops this is typically where the moisture content is highest and ice could form quickly
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If Ice does occur act quickly and get out of those conditions
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The pencil-like OAT probe is often a good indicator of incoming ice
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If icing does occur, keep the speed up, don’t fly too slowly as stall speed has
increased
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Be aware that the stall warning system may have iced up
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Treat any snow stuck to the aircraft’s surfaces as ice
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If you are in trouble notify ATC early on and squawk 7700 if necessary
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Ice forming on an aircraft can cause weird noises and vibrations, don’t panic,
Fly The Aircraft!
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In-Flight – Landing
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If when approaching the airfield the windscreen is
obscured, either wait for ice/ snow to melt, or use DV
window.
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Even a thin coat of ice can require a 20% increase in
approach speed
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This will also increase the landing distance on what
could be a slippery runway
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If you suspect tailplane icing, a flapless landing may be
necessary or as the POH instructs.
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If ice has built up on the tailplane whilst being flown on
autopilot it may have auto-trimmed significantly nose
down and a large control force on the yoke may be
required upon disconnect.
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Remember ground temperatures may have fallen in
late afternoon and any water on the runway may have
frozen!
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After Flight
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Be careful when getting out of the aircraft, assume all
surfaces will be slippery!
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Use control locks and park into wind
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Remember to put pitot covers on once cooled down!
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If mud or slush is present clear out of fairings and bays
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Notify air traffic if actual conditions were worse than
forecasted, it’s important for other pilots to know
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Summary
• Stay out of icing conditions for which the aircraft has NOT been cleared.
• Note freezing level in the aviation weather forecast. Don’t go unless the aircraft is equipped for the conditions.
• Have warm clothing available for pre-flight and in case of heater failure or forced landing.
• Mud, snow and slush will lengthen take-off and landing runs. Work out your distances.
• Remove all frost, ice and snow from the aircraft – there is no such thing as a little ice.
• Check carefully that all essential electrical services, especially pitot heat, are working properly.
• Check that the heater and demister are effective. Watch out for any signs of carbon monoxide poisoning.
• Be extra vigilant for carb ice.
• If ice does start to form, act promptly, get out of the conditions by descending (beware of high ground), climbing or
diverting.
• If you encounter ice, tell ATC so that others can be warned.
• During the approach if you suspect tailplane ice, or suffer a severe pitch down, RETRACT THE FLAPS or as POH instructs.
• If you have to land with an iced up aeroplane, add at least 20% to the approach speed.
• Snow-covered, icy or muddy runways will make the landing run much longer and crosswinds harder to handle.
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References
Anon, (2014). [online] Available at: http://www.faa.gov/documentlibrary/media/advisory_circular/ac%2000-6a%20chap%201012.pdf [Accessed 15 Nov. 2014].
Anon, (2014). [online] Available at: http://flighttraining.aopa.org/pdfs/SA11_Aircraft_Icing.pdf [Accessed 15 Nov. 2014].
Anon, (2014). [online] Available at: http://www.crh.noaa.gov/images/lmk/Brian%20S/LMK_Icing_Show.pdf [Accessed 15 Nov.
2014].
Anon, (2014). [online] Available at: http://www.jumpjet.info/Emergency-Preparedness/DisasterMitigation/Climate/Aircraft_Icing.pdf [Accessed 15 Nov. 2014].
Anon, (2014). [online] Available at: https://www.caa.co.uk/docs/33/20130121SSL03.pdf [Accessed 15 Nov. 2014].
Anon, (2014). [online] Available at: http://www.caa.co.uk/docs/33/20130121SSL14.pdf [Accessed 15 Nov. 2014].
Aopa.org, (2014). Cold Weather Operations. [online] Available at: http://www.aopa.org/Pilot-Resources/Safety-andTechnique/Weather/Cold-Weather-Operations [Accessed 15 Nov. 2014].
Pilotoutlook.com, (2014). Aviation weather -Icing. [online] Available at: http://www.pilotoutlook.com/aviation_weather/icing
[Accessed 16 Nov. 2014].
Training.deicinginnovations.com, (2014). [online] Available at: http://training.deicinginnovations.com/wpcontent/gallery/ice/s1240038.jpg [Accessed 15 Nov. 2014].
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Wikipedia, (2014). Icing conditions. [online] Available at: http://en.wikipedia.org/wiki/Icing_conditions [Accessed 15 Nov. 2014].
Safe Flying
By Harry Hayon and Steve Morley
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