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Cold Weather Flying
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Cold Engine Starts; ...Long Layoff Start; ... Pre-heat; ...Cold Weather Flying; …Defrosting: ...Cold Flight Checklist; ...Icing and PIREPs; ...Flight in Icing; ...Icing; ...Tail Stall; ...Survival Kit; ...Survival Basics; ...Fears in Survival Situations; ...Enemies of Survival; ...Rules of ABC; ...Crash Survival; ...Winter Clothing; …Living with Weather Delays; …Weather Avoidance; …Fog; …Cold Weather Cross-Country Planning; …Seven Aircraft Considerations; ...Ice Prevention; …Signs of Ice; ...Snow, Ice or Frost on the Wings; ...Opinion; ...On Icing; ...Levels of Icing; ...If You Can't Avoid Ice; ...Icing Certification; …Cabin Heat; … Snow Rhymes with No; …Winter Fronts; … Flying in Cold Conditions; … TKS (mix of glycol and alcohol); …When It Gets Cold; ...Winter Flying; ...Icing in Brief; ...Altitude Lower than Indicated; ...Thermal Conductivity of Aluminum and Composite Aircraft; ...

Cold Engine Starts
Even in California it can get cold enough to cold-soak an engine.

Long-layoff Start
A cold start stresses the engine, the starter, and the battery. Engines and their accessories should be preheated below 20-degrees F. You control only the fuel/air mixture. Only atomized fuel can be made explosive. Cold fuel does not evaporate as well as warm fuel so more time is needed to create the starting mixture. Pre-oil if you can by gaining access to interior of engine through an accessory port. Otherwise, pull the plugs and spray an oil mist into cylinders. (Use Marvel Mystery Oil) Now turn by hand to get oil pressure. After starting fly for at least an hour to make sure all moisture is burned out.

Turn the cold engine over a couple of times with the fuel off to clear the induction system. Next use the primer to put fuel into the induction system. This pump has jets that spray fuel into the intake manifold. Do not pump the throttle since pumping the throttle squirts a stream of gas upwards only to drip back down. This fuel can drip down and cause a engine fire if ignited by a backfire.

A cold start begins with two to three pumps of the primer. Lock the primer. Wait two to three minutes to allow the cold fuel to vaporize. As you begin to turn over the engine give a quick pump of the throttle.

If your engine does not have a throttle accelerator pump, you should leave the primer unlocked and fully extended ready to pump. Pull the throttle all the way out to 'choke' the engine. As soon as you turn over the engine give the primer pump a quick shot to enrich the mixture and lock it.

Pre Heat
You can use two 100 watt trouble lights inserted up through the cowl flap. This arrangement can give you > about a 40-degree temperature rise (use caution that the lights cannot break or damage any wiring or oil and fuel lines). Regardless of the system you use always pre-heat with an engine cowl blanket installed, this helps keep the heat around the engine." For the specifics on a cowling blanket, engine and cowling covers, you'll find all the information on the Cessna Pilots Association (CPA) web site under the Sources For... S-07, "Preheaters".

Oil Analysis
Howard Fenton at Engine Oil Analysis, 7820 S. 70th E. Avenue; Tulsa, OK 74133-7805.

Cold Weather Flying
Cold checklist
1. Have a new CO patch in the cockpit
2. Confirm with your mechanic that the muffler is o.k.
3. Winterize your engine and pre-heat your start (Drill out breather tube)
4. Provide for cockpit survival. with survival clothing
5. Check static and pitot for ice
6. Make sure quick-drains drain
7. Consider warming battery
8. Remove ALL ice, snow and frost.

Use a garbage bag filled with 10 or so gallons of hot water, knot the top and then wipe the top of the frost. This melts the frost and polishes it. As it re-freezes, the airfoil shape is maintained. Usually end up using 4 or 5 refills, and couple new bags, takes about 10 to 15 minutes.

Cold Flight Checklist
1. Only fly into improving weather
2. Know where to go to escape
3. Keep alternatives available
4. Runway lengths, surface and widths become critical

1. Because of the cold the cold weather pilot tends to abbreviate the preflight. Don't!
2. Look for fuel dye as indicative of fuel leaks.
3. Keeping the tanks full keeps out moisture.
4. Ice in fuel looks like floating dust.
5. Check engine cylinders and exhaust fittings for white stains.
6. Prime 50% more than normal when it's cold and 100% if really cold.
7. Use manufacturer's recommendations for cold weather operations
8. If heat baffles are used check their security. Is a baffle called for over the oil cooler?
9. Let engine warm up until oil thins out and pressure is normal.
10. Crankcase breather hose and system must be free of moisture.
11. Hoses, flexible tubing and seals become brittle in cold
12. Battery and charging system should be in good condition
13. A cold battery will be weakened unless fully charged
14. Cold oil will be more viscous (thick)
15. Control cables' lubricants will congeal. Check throttle and CH.
16. Don't use anything that works on an automobile to remove ice
17. Deicing fluids cause corrosion and leave unpleasant residue
18. Keep fuel tanks full and protect against contamination. Super-cooled fuel can create ice crystals and a rough engine. C.H. helps.
19. Preheat engine and cockpit prior to start when 10-degrees F. Heat under constant attendance and not directly on surfaces.
20. Store in heated hanger until just before departure
21. Don't let water get on hinges or movable parts.
22. Clean and dry pitot tubes, heater intake, carburetor intake, control surfaces and wheels.
23. Melt ice and remove all moisture, which may freeze again. Use hot water bottles or double-bagged plastic bags and plenty of dry towels
24. Check weep-holes under aircraft and drain interior moisture.
25. Confirm fuel selector is not frozen in one position.
26. CO detectors are recommended in addition to heater inspection

1. Thirty seconds of cranking = 50 hours flight time wear
2. Phone your destination just prior to departure
3. Plan to walk home.
4. Electrical loads will be heavier.
5. Don't set parking brakes, hot brakes will freeze solid.
6. Idle at higher rpm to keep plugs from fouling and oil hot
7. Normal engine temperatures are required to evaporate moisture in crankcase.
8. Change tanks more often so that maximum fuel is available. Fuel selector might freeze.
9. Flooded? Mixture out, throttle full. Crank 20 seconds.
10. Fuel/air more reluctant to ignite. Carburetor heat may be required for takeoff
11. Don't use throttle to over prime (two strokes maximum). Use engine primer, not throttle.
12. Most common cause of aircraft engine fires is prime with throttle
13. Prime only with primer. Over priming can be harmful.
14. If RPM rises when carburetor heat is applied it means that air filter is blocked
15. Don't try to force the warm-up
16. Gyros will need to warm up and speed up, too
17. Control cables will be tighter and stiff
18. Don't hand prop.
19. Keep wheels and brakes as dry as possible
20. May need to remove and dry plugs if engine fires only briefly.
21. Use radios only after electrical system has run a few minutes.
22. Braking may be poor to nil
23. Oil must be hot to perform properly. More viscous (thick) oil requires more cranking energy
24. Fix problems early before they become 'unfixable'.
25. Consider landing gear up
26. Use C. H. in icing range
27. Use C. H on approach and descent
28. Keep power up during descents and extend any drag that may be available. This will keep the engine warmer.
29. Taxi slowly, wheel bearings may be frozen, brakes may not hold.
30 Don't use flaps if tailplane icing is at all likely.
31. Don't use brakes until tires are on hard surface. Be prepared for ineffective braking. Touchdown areas of runways are more slippery.

1. Performance on runway may be less.
2. Reduce crosswind capability by 50% for snow and 75% for ice
3. On getting airframe ice, change altitude.
4. Climb through ice at high speed and shallow angle.
5. Descend through ice at lower speed but high rate of descent.
6. Climb above wet snow and freezing rain.
7. Reduced windshield transparency makes surfaces appear lower than they are. 5-degree slope errors are common.
8. If your planned altitude is within 4000' of z-level anticipate ice.
9. Plan an alternate route around convective weather.
10. Know the "times" as they apply to your flight. (fuel, battery, speed, alternate, etc)
11. Set power at cruise and don't change anything. Thus, if anything changes it means there is a change in power. Suspect carburetor or induction icing.


1. Ramp operations can cause 'black ice' problems for taxiing.
2. Weather systems move more quickly in winter. Fast-moving winter systems create turbulence and hazardous conditions.
3. Just because no ice is forecast doesn't mean there won't be any.
4. If you are flying in air only 10 degrees above z-level anticipate ice.
5. Freezing weather can make a survivable problem non-survivable
6. Where is the good weather?
7. Expect strong winds from the wrong direction
8. Snow changes the way things look
9. Light icing over a time is a serious problem
10. Ice usually exists under snow.
11. Moisture on runway that gets on aircraft may freeze when airborne.
12. Clouds dropping rain have less ice potential than do those without rain.
13. Top portions of clouds contain supercooled droplets.

Icing and PIREPs
Perhaps the reason there is a significant shortage of PIREPs is because not many pilots fly in the weather likely to make a PIREP important. PIREPs are especially good when they are about icing and turbulence but they are often just a snapshot and lose validity unless the pilot can fill in the whole picture. According to FAR 91.183 an encounter with unforecast icing requires a PIREP. The giving of a PIREP should be an independent communication and not given as a part of routine route information. The rate of ice accumulation is more important than the kind of ice. The AIM has an ice accumulation rate table which for accuracy must be judged by someone who flies only in ice. War story example follows:

Prior to a late fall afternoon Reno departure for the Bay Area with a stop at Truckee, I visited the Reno FSS and studied the satellite pictures. The route had clouds above 12,000' with icing in clouds. The flight to Truckee was uneventful but it was apparent that the cloud level was less than 12,000'. Prior to our Truckee departure we made radio contact with FSS which confirmed lowering conditions with icing in clouds. On departure we monitored the FSS and were advised that just a few minutes before a Cessna flying out of Reno on a route slightly south of our planned route had reported moderate icing and hail.

We advised the FSS that we would take a look before canceling the flight. We proceeded below the clouds to fly via Interstate 80 to Sacramento. We maintained contact the Reno FSS until we started our descent into the Central Valley. Without my previous visit to the FSS in Reno I would not have had the bigger picture which showed the worst of the weather to be southeast of our planned route. Even with the lowering clouds there was ample margins of safety related to freezing levels and no visible precipitation along the route. A PIREP along our route would have given us a couple more days in Reno.

Forecast icing. according to the NTSB, is the same as known icing. The fact that the entire flight was VFR without any precipitation meant that by picking our route carefully we avoided both weather and FAA problems Last year I did inform ATC that we had snow in the cockpit. I don't know what conditions caused the cockpit snowstorm but precip filled the cockpit for about ten minutes. On another flight the same year asked ATC for higher so my student could get some actual. At 13,000 we got into a cloud that caused a rapid accumulation of rime ice. We immediately asked for lower and proceeded at 11,000 as the ice gradually disappeared. In every one of these icing encounters I always maintained continual radio contact and radar if altitude permitted. I have kept backdoor openings for every icing encounter. ATC is required to get PIREPs when a ceiling is below 5000' or 5-mile visibility. An ATC request for flight conditions is a request for a well-constructed PIREP with special reference for thunderstorms, icing or turbulence.

Incidentally, there is no record of the FAA violating a pilot for having presented icing PIREP. Declaring an emergency because of icing is a viable option regardless of the consequences since it assures you of any help you may need short of deicing ability.

The system relies on good PIREPs. PIREPs are used to expedite traffic. A SIGMET or AIRMET can be issued based upon a well reported PIREP. Many thousands of commercial aircraft now carry the Aeronautical Communications Addressing System (ACARS) that report winds and temperature. The Future GPS downlinks will be capable of continuous meteorological data downlink streams.

Without 'known icing' ability you should stay out of visible moisture when the outside air temperature (OAT) is below freezing. Part 91 flights are prohibited from flying into known icing. FAR interpretations consider forecast and known as identical.

Flight in Icing
All exterior sensors, pitot, static, and stall warning will be degraded as to sensing ability and accuracy. Antennae efficiency can be changed. I have had radio transmitter relays freeze in the cockpit so that they would not operate for transmission. (We used a handheld) Propeller unbalance is common. Fly at faster speeds than normal in climb, descent and especially landing. Most icing happens in visible moisture with temperature between zero and -14 C. Less than 10% of ice accidents occurred when ice was worse than forecast. No aircraft is certified to fly in moderate freezing rain. Any flight into forecast icing is considered by the FAA as a violation of FARs 91.9 and 91.13. by exceeding operating limitations and being careless and reckless.

As ice accumulates and lift decreases, the pilot must increase the angle of attack to retain lift for level flight. In this condition ice begins to accumulate beneath the wind and tail surfaces. You can't see ice below the wing in many aircraft. Any de-ice capability should be used only to escape the icing, not to continue the flight. You cannot afford to be casual while operating in ice. You need to be current in your skills related to unusual attitude recovery.

Carburetor ice is far more likely to occur and cause an accident than is airframe icing. 51% of icing accidents are caused by carburetor ice or induction system ice. The cause of this ice is the failure of the pilot to ANTICIPATE the possibility of ice by applying full carburetor heat and alternate air. The fixed pitch plane will develop a rough engine while the constant speed plane is going to show a drop in rpm. Under icing the C. H. will increase the roughness of the engine. Leave it on. Use alternate air if available.

0. The one-hundred-eighty turn is on record as having saved more lives than governmental inertia have killed.
1. Visible rain at below freezing temperatures
2. Splashing or splattering rain drops at below freezing temperatures
3. As for immediate priority ATC handling
4. Avoid abrupt or excessive maneuvers.
5. No autopilot
6. Reduce angle of attack if aircraft tends to roll
7. Do not extend flaps
8. Do not retract flaps if extended.
9. Report conditions to ATC
10. Structural icing is least likely to occur in high clouds since they are formed mostly of ice crystals.
11. An encounter with ice pellets is indicative of freezing rain above.
12. You know that if you fly into rain that freezes on impact that the temperature is warmer at a higher altitude.
13. If you encounter wet snow, you known that the temperature is warmer than freezing.
14. A surface inversion is most frequently produced by terrestrial radiation on a clear calm night.
15. The surface temperature being below the dew point with the air and dew point below freezing causes Frost. Water vapor then sublimates directly as white and opaque ice crystals or frost.
16. Whenever icing is a hazard it will be forecast in sigmets and airmets.
17. Standing lenticular clouds are indicative of severe turbulence.

Tail Stall
This stall can occur when ice accumulates on the bottom of the horizontal tail surfaces to such an extent that the flow
of air ceases to give the required download. The tail stall occurs on the bottom side of the horizontal tail surface.
This lack of airflow can be even further reduced with the application of flaps and an increase in airspeed. Flaps will increase the downwash angle of the over tail air stream and increase the negative angle of attack. This can result in an abrupt nose down attitude and descent. The recovery is completely different from a normal stall recovery. Flaps are removed. Power is reduced and the yoke is pulled back. Pipers are subject to this more than Cessnas.

The do not use flaps if icing exists or is suspected. You will not be able to see ice on the bottom of the horizontal tail
but any ice accumulation will occur there first. Fly the approach at a speed that will account for ice created drag but
not extra fast that will increase the downwash on the tail surface. More downwash increases the tail stall possibility.  So long as airflow stays attached to the bottom of the tail, it is flying. You will have control and down pressure from the tail.

The full stall does not occur until both the low-pressure (top) of the wing and the (bottom) of the tail surfaces lose all their lift. (I urge you to think through the "download" effect of the tail surfaces since it is often part of the Practical
Test oral.) This doesn't happen. With all low pressure surfaces having some effect the aircraft does not go straight down. The tail is being held down by low pressure below the horizontal tail surfaces. With ice on this surface it will
have reduced effectiveness and power. If flaps move the center of lift for the wings backward an abrupt nose down pitch is most likely to occur.

The tailplane will collect ice more readily than the wing. The collected ice will more adversely affect the tail-plane's downward loading than would the same amount of ice on the wing. Ice may be on the tail before appearing on the
wing. Boot deicing on the tailplane is less effective than on the wing. An icing tailplane stall may be unrecoverable.  The icing you get may be quite different from the icing used for certification. The tailplane may be colder than the
outside air temperature (OAT)

Advice: Don't use flaps if you suspect ice. Don't mess with ice. If the freezing level is on the ground, you won't be able to descend to warmer air.

Survival Kit
1. Textbook ..........................16. Compresses
2. Waterproof matches/tinder 17. Tapes
3. Water-flexible package .....18. Aspirin
4. Space blankets/tarp ..........19. razors
5. Multi-Knife .......................20. Signal mirror
6. Fire starter ........................21. 5-day rations
7. Large trash bags ...............22. Bouillon cubes
8. Flashlight ..........................23. whistle
9. First aid kit .......................24. Survival saw
10. Take compass from plane 25. Survival candle
11. Insect repellent ...............26. Chemical lightsticks
12. Sun screen/balm .............27. Gloves
13. Hacksaw blades .............28. Hard candy
14. Vice grip/ pump pliers .....29. Toilet paper
15. Sealable container ..........30. Razor blades

Survival Basics
1. Get out NOW, take what you can.
2. Treat injuries, stop bleeding, keep warm, immobilize
S is for STOP
T is for THINK
0 is for OBSERVE
Knowing where you are is half the solution
Mark any trail used.
P is for PLAN
Select a leader, conserve energy, improvise.

Fears in Survival Situations
The unknown, darkness, discomfort, being alone, animals, death, punishment, and personal guilt.

Enemies of Survival
Yourself, injuries, temperature, disease.

Rules of ABC
Survival is 80% mental, 10% equipment, and 10% skills
1. Get what you need. Fire materials off trees not ground - 3 times what is needed. Get water - vital for survival  (Use plastic containers) Conserve energy lost due to shock of accident. Rest before making survey of area and making
survival preparations.

2. Inventory
Attract attention. Three fires are distress signal.

3. Select alternative that takes least time, energy, material.

4. Make for safety and durability.
Aircraft hull may not be best choice.
Get off ground or under ground out of wind and wet.
Best bet is to stay with aircraft.

5. Desire for survival is essential.
Salvage aircraft parts as containers, remove compass, gasoline,
oil, upholstery, wiring, battery, hoses.

6. Heat water before drinking to conserve body heat. Wear dry clothing
as much as possible.

Crash Survival
#1 survival item is to let a responsible person know where you are going, your route, and ETA. Insurance is to make contact after arrival. If you are not found quickly, you are not likely to be found at all.

Survival items that are nice to have, short-term and essential for longer are:
Flashlight, digging tool, foul-weather gear, blankets, food, water, matches and candles. A real plus would be a
portable GPS, a handheld radio, or a cellular phone. Dehydration is the worst threat usually facing a downed pilot.

Winter Clothing
Combine high-tech and traditional materials. It is easier to keep warm by wearing multiple layers. Inner lawyer should not absorb moisture and wick it away from the body. 1/4 of body head leaves via the head. Waterproof headgear may be the most important single survival item.

Pilots are optimists that believe bad things happen to other people. They believe that flying is so safe that there is no need to be prepared for catastrophe. Before leaving home you should prepare the 'what if' options. Whenever you go flying you should be dressed to walk home. You should have required items within cockpit reach. You should stay with aircraft and survive until conditions allow foraging. Short-term rescue is usually within a day. The greatest danger is exposure to conditions causing hypothermia. The right condition of wind, temperature, and moisture can expose anyone to hypothermia. The body loses heat most rapidly when wet.

Making your position visible can help rescue. Make a clearing, start a fire, and make large SOSs. Use common sense, have confidence in yourself and be patient. Prior planning, preparedness, practice and training will enable you to make the best decision possible.

Pilots fail more frequently than do any other facet of aviation.

Living with Weather Delays
Enjoy the weather delays they are going to occur more often than not…
1. Take a ground, simulator, or local flight lesson.
2. Make new friends
3. Visit the local ATC facilities
4. Go to an alternate airport and rent a car.
5. Now you have time to visit the local tourist trap.
6. A gambling casino can't be far.
7. Shopping is always an alternative
8. Look at the weather and be thankful you're down instead of up.

Weather Avoidance
Certain trips require better weather management than others. Understanding the weather you get is far more important than just making a collection of weather elements. A failure to understand mean that flight planning may proceed when it should be delayed, moved faster or skipped all together.

The preflight weather planning is the time to make flight decisions. Based on what you know about the weather you must decide if you are capable of making the flight in the face of forecast weather, terrain, and available facilities.

Once underway you are more in need of real-time weather. This means you will contact every HIWAS, ATIS, AWOS, ASOS and Flight Watch along the way. You will seek PIREPS because they are the most real-time weather you'll ever get. You will give PIREPS and stay in contact with Center where you can get CWAs (Center Weather Advisories) and CWSUs. Don't delay asking for help such as higher, lower, vectors, nearest airport

War Story:
In late May of 2000 I made a flight to Illinois and back to California over a period of six days and 42 hours of flying in a C-172. This involved considerable such planning as above. I was not certain that I would depart until the moment of my departure. We had a terrible storm two days prior to my departure. I watched it move through and past. I knew my greatest risk lay in catching up with the storm. On the second day of my trip I caught up with it
near Kansas City.

Near Salina, KS I could no longer maintain VFR so I asked Center for an IFR Clearance. They could not give a clearance without radar contact. I made a slight change in direction and was able to gain a thousand feet where they
had radar contact. I climbed to 5000 and proceeded toward Johnson County Airport. I was near the tops of the clouds because the sun would occasionally shine through. No turbulence or problem. When I was handed off to K.C. Approach, I advised that I had no plate. I was read the plate numbers and frequencies for a Localizer Approach. No problem.

I departed VFR and flew across Missouri to southern Illinois under 2500' ceilings while all the bad weather trotted further east since I broke out at about 1800 feet. No significant weather the rest of the trip. The making of weather decisions is difficult to teach without actual exposure. Experiencing weather is the best way to gain weather judgment. The experience needs to be weather specific and acquired in bits and drabs. Shock treatments of weather may not
be survivable. We all remain vulnerable to weather and being aware of this is a source of very desirable caution.

Fog occurs when the air close to the ground reaches the dew point. Of the basic types of fog, radiation fog is the most common. Radiation fog forms on clear nights since clouds tend to warm the earth and air. Radiation fog is
usually less than 300 feet thick. A light wind tends to make the fog even thicker. The rising sun lifts the fog and eventually breaks through. Any moisture on the earth evaporates and creates more fog. For this reason it is not unusual to have radiation last all day.

Advection fog comes with the on shore winds as it blows across a colder surface and causes humid air to form fog.  This fog is then blown or more likely 'sucked' inland as a layer of fog over the earth. This fog first covers the lowlands and can then be forced over hills and mountains as upslope fog.

When a moist front arrives the associated rain can form precipitation fog. If the air is near freezing this front will form ice fog. In some circumstances the start of an engine can provide the needed moisture to create ice fog.

Cold Weather Cross Country Planning
Radar facility controllers are required to be familiar with and advise aircraft of any icing conditions within 150 miles of their sector. Get a diversion before it becomes an emergency. It is illegal to plan or fly into a situation where icing
is even mentioned in weather information.
--Follow roads
--Have an ETA destination contact
--Wait a while and the weather will change
--Weather stations are sparse
--Prepare a survival plan
--Get clear of plane and stop
--Survival is 80% mental
--Your fears are your worst enemy
--Check ELT operation
--Use the aircraft
--Survival is 10% equipment
--Get dry and sheltered
--Care for injuries
--Garbage bags
--Survival is 10% skills
--Don't eat snow
--Eat sugar
--Get out of the wind

Aircraft Considerations
--Use POH to set manufacturers requirements
--Get a cylinder head temperature gauge
--Modify crankcase breather system
--Check hose lines for flexibility
--Check heater system
--Get electronic monoxide detector
--Get maintenance check of control cable tension
--Do not feather propellers that may not unfeather
--Keep battery fully charged or remove for warm storage
--Remove wheel pants
--Do not recycle wet landing gear
--Refill tanks immediately after landing
--Refuel only when aircraft is level
--Check quality of fuel
--Imitation chamois will not filter water from fuel
--Use only aviation approved filters
--Have quick drains on all tanks
--Inability to drain well may be indicative of ice in fuel.
--Use anti-ice additives
--Use proper heater to preheat engine compartment
--Do not put heat directly on accessories
--Store in heated hangar if available
--Check POH procedures
--Congealed oil and grease can affect engine and controls
--Turn by hand before trying starter
--Avoid over priming
--Have fire guard present
--On first try water/ice may condense on sparkplugs. Removal necessary.
--Idle at RPM sufficient to warm plugs
--Use carburetor heat to help vaporize fuel
--Allow to warm up before use
--Heated hangar is best option
--Do NOT use water
--Use alcohol
--Don't fly until all snow and ice is removed
Blowing Snow
--Check all openings and intakes
--Check all controls
--Check fuel vents
--Braking may be nil
--Ice exists below snow layer
--Check ski shock cords and safety cables
--Get help when taxiing down wind
--Control surfaces will be ineffective
--Cold weather both helps and hurts G.A. flying
--Engine power increases 1 percent for each 10 degrees below standard temperatures
--40 degrees of temperature can give a 10 percent power increase at normal settings
--With reciprocating engines, use carburetor heat as required.
--In some cases it is necessary to use carburetor heat to vaporize the fuel.
--Gasoline does not vaporize as readily at very cold temperatures.
--Do not use carburetor heat in such a manner that it raises the mixture temperature barely to freezing or just a little below.  In such cases, it may be inducing carburetor icing.
--It may be advisable to use carburetor heat on takeoff in very cold weather.
--An accurate mixture temperature gauge is a good investment for cold weather operation. It may be best to use carburetor heat on takeoff in very cold weather.
--Do not over-boost supercharged engines
--Turn on pitot heat
--With engine baffles the engine will overheat on climb-out
En route
Carburetor Ice

The three types form between 32 and 80 degrees F even when visible moisture does not exist. When visible moisture exists the formation can occur between 15 and 32 degrees F. Partial throttle operation is the most critical time. Use carburetor heat prior to power reduction and use power during descents to maintain carburetor heat effectiveness.
Impact Ice
--Moist air between 15-32 F on air scoops throttle plates
--Worst at 25F
Fuel Ice
--Forms throughout when moist air freezes through vaporization
--Usually between 40 and 80 degrees F and relative humidity over 50%
Throttle Ice
--Forms at or near throttle valve. Freezes due to venturi effect cooling by 5 degrees
--Dangerous temperatures from 32 to 37 F

Ice Prevention
--Ground check CH prior to takeoff
--Use heat when carburetor temperature gauge is in the icing range.
--Use heat on approach and descent

Signs of Ice
--Loss of RPM or manifold pressure
--Rough engine
--Apply full carburetor heat
--Expect engine to run rougher until ice melts

Snow, Ice, or Frost on the Wings:
--Never attempt to takeoff with any ice or frost on the aircraft
--Ice and frost can cause an aircraft to have sudden and violent stall characteristics.
--Any stall caused by ice or frost may be unrecoverable
--Below a layer of snow on the aircraft there is probably a layer of ice
--Any ice caused roughness of the upper wing will cause a 10 percent increase in the stall speed
--If airborne, any turbulence could result in an unrecoverable stall
--Any precipitation that changes the wing's surface will increase the stall speed.
--Flight should not be attempted where the wing's surface has been affected.
--Stall speed and stall characteristics are determined with clean airfoils.
--In icing conditions the usual cues for stalls and control problems may not exist.
--Once stalled recovery may not be possible.
--At best, large losses of altitude can be expected.
--Only rapid and positive applications of power and AOA have any chance against configurations causing up to 50kts increase in stall speed.
--Any use of the autopilot is likely to conceal icing problems.

Frost will usually sublimate off the wings quite quickly in the air. This is particularly true in cold dry air. However, the roughness caused by the frost may well preclude your getting into the air in the first place! I used to use a special towel that I made by sewing large bath towels together end to end. I could throw one end of this over the wing and
polish the frost smooth. Once I got it smooth, the airplane would fly just fine and before long all the frost would be
gone. However, it must be smooth.

On Icing
…If weather briefing includes chance or reported icing…Don't go.
…Avoidance begins with preflight planning
…Don't fly winter fronts
…It's worse over high terrain
…0 to -10 C-degrees gives clear ice
…-10 to -20 C-degrees gives rime ice
…Freezing drizzle is worse that freezing rain.
…180 is usually best decision
…Pitot heat, C.H. and alternate air
Q: What affect on performance does the accumulation of airframe ice have on an airplane?

A: Airframe icing, also known as structural icing, can be a very serious situation, especially to an airplane not certified for known ice. As ice accumulates on airframe surfaces, it changes the shape of the airfoil, increasing both drag and weight while reducing lift. Additional thrust is required to maintain altitude and airspeed and to avoid a stall since the stall speed also increases. It doesn't take much accumulation of ice to affect your performance. Only a half-inch of ice can reduce lift by 50 percent. For definitions of in-flight icing terms, view Chapter 7
( ) of the "Aeronautical Information Manual." For additional information, see the AOPA Air Safety Foundation's Safety Hot Spot on aircraft icing
( ) and see AOPA Online
( ) for a
description of "known icing."

What Is Icing?
Timely evasive action is the best option
--Ice will be on the tail when you see it elsewhere.
--Do not slow down nor use flaps when ice may be on the tail.
--Have an Icing checklist the includes petot heat and alternate air for starters.
--There is no FAR that prohibits a Part 91 from flying in icing conditions.
--If your aircraft has a placard, marking of AFM limits flying in ice, don't fly in ice.
--AFM in the limitations section precudes flight into known icing.
--A PIREP is the only way that a pilot can know of 'known icing'.
--When the tops and bottoms of clouds exceed 4000' there is ice in there.
--When freezing level is below the clouds there is ice in the clouds.
--You can usually evade ice by changing altitude.
--Waiting to change altitude is not an option.

Levels of Icing
Trace---you can see it but it does not sublimate nor accumulate

Light--In an hour the increase in ice would be a problem.

Moderate--accumulation rate requires diversion immediately.

Severe---You should have never entered the conditions.

If You Can't Avoid Ice
--1/32 of ice on wing can reduce climb rate by 300fpm
--Outside air temperature is critical from 0 to 20 below
--Watch small-radius parts of the aircraft
--Know your minimum enroute altitudes
--Get on top as soon as you can, stay there as long as you can
--Don't fly into a front or low pressure area
--Be on the ground at night
--Advise ATC
--Make a 180
--Cycle the propeller to throw off ice
--Avoid the cloud tops
--Fly faster without flaps

Icing Certification
Flight into icing is based upon maximum continuous and maximum intermittent icing conditions in mist conditions at icing conditions. No certification exists for flight in freezing drizzle or rain. Fly as fast as you can.

Cabin Heat
The air comes in through the nose of the aircraft as allowed by the cowling baffling. A flexible tube guides the air into the metal outer cover or shroud around the aircraft muffler. The region between the muffler and the shroud has a
series of thin metal partitions that absorb the heat from the muffler and allows the ram air to flow and absorb the heat. This air is safely separated from the poisonous carbon monoxide passing through the muffler and exhaust pipe. When the cabin heat control is pulled it opens a door that allows the heated air from the interior of the shrouded area to enter the cabin by way of selected vents. If a leak should occur, and it can, the use of the cabin heater could
allow carbon monoxide to enter the cabin and incapacitate or kill the occupants. The odor of other engine gases other than carbon monoxide is a clue that there is a leak. Carbon monoxide has no odor.

Snow Rhymes with No
--When bad weather conditions are approaching, the sooner you leave the better.
--Don't let ATC procedures delay a departure likely to be made hazardous by approaching conditions.
--A negative for snow is that it often has ice beneath.
--Most winter ground accidents are caused by snow banks and berms created by plowing.
--Snow reduces visibility more than rain does.
--Be prepared to use full control deflection when dealing with snow on the ground.
--When snow covers the nosewheel 1/3 of the way consider inability to accelerate.
--Snow storms average a life of 18 hours from first to last flake.
--Snow plowing begins with the longest runway, then taxiways and the ramp. G.A is always last.

Winter Fronts
--Cold fronts move behind the thunderstorms
--Warm fronts cause stratus, rain and low ceilings
--Winter cold/warm fronts have close temperatures
--Flying hazard is turbulence, winds, and clear icing near cold fronts.
--The speed of the front movement directly related to wind velocity and extent of turbulence.
--Winter warm fronts have terrible flying weather including freezing rain
--Winter warm fronts have rime icing in stratus clouds.
--Occluded front is two fronts with the worst weather of both relatively stationary.
--Tops of winter clouds are lower and can be overflown.
--Snow that is melting gives rise to severe fog conditions.
--Northeastern movement of lows make that side a bad place to fly.
--Northeast side of a low is a no-fly zone.
--Freezing level is region of freezing rain and clear ice.
--Worst airframe icing occurs at -2 to - 5 degrees Celsius
--If aircraft is capable, freezing layer is 1000 feet thick. Turning is best option to avoid precipitation.
--Three number code identifies type of front, intensity and trend

Flying in Cold Conditions
--Weather is more likely to clear than during summer.
--Total operation of aircraft is more efficient in cold weather when in the air.
--Ground operations are more difficult.
--Keep your headset and flashlights warm.
--A low battery can freeze.
--A clogged oil breather can cause engine failure through loss of oil.
--Daylight starts later and ends sooner. Carry more flashlights.
--Thunderstorms are less likely.
--Don't get into an airplane with snow adhering to you or your clothing.
--Carry survival equipment
--The worst wear occurs in the first few seconds of engine operation before oil becomes effective.
--Preheating of the engine is the preferred way to get near instant oil where needed.
--For most situations an engine and oil heating system is better than just engine or oil heating.
--There are harmful effects to heating anything but the entire engine at the same time.
--There are many negatives to continuous preheating.
--Break engine oil by rotating propeller if preheating is not available.
--Fuel gets thicker and less volatile when cold. Warm the whole aircraft.
--Wear appropriate clothing and shoes. Sleeping bag may be needed.
--Silicone spray can keep propeller ice-free for a while.
--Deice hinges and check control cables for free movement.
--Cockpit engine controls must be free…check/
--Turn on pitot heat during preflight to confirm operation and melt any internal ice.
--Heating the cockpit includes the instruments with bearings subject to damage due to cold.
--Another opinion is that more prime is required when cold.
--Check alternate air as part of preflight.
--Expect reluctance of engine to start, frosted spark plugs, and a weak battery.
--Some find Continentals easier to start than Lycomings in cold weather.
--When cranking have the primer out and ready to give a squirt when/if the engine fires.
--Taxiing with any form of moisture on the pavement can induce loss of control.
--Much of the hazard of snow on the ground is what it covers. Ice is worst.
--Light frost can reduce lifting capability of a wing by 30 percent.
--Depth perception is greatly compromised when snow covers everything.
--Under certain combination of snow on the ground and clouds in the sky where will be no horizon.
--A flying arrival into colder conditions means actual altitude is lower than indicated altitude.
--Proper crosswind control positions are more vital than ever on a slick runway.
--Ice with water on top is the most dangerous condition whether taxiing or landing.
--Dew on the pavement can cause viscous slipperiness and reverted rubber hydroplaning.
--Reverted rubber hydroplaning leaves a white skid mark. Runway has been steam cleaned by friction.
--A worn tire hydroplanes more quickly than a new tire.
--Braking is best with a 20 percent rolling skid.
--A crosscut grooving of 1/4 inch slots gives a wet runway dry runway braking.

TKS (mix of glycol and alcohol)
--Very expensive liquid ($22 per gallon) and spreading system costs $25,000+ per aircraft
--Flows and protects entire aircraft from adhering ice.
--Better than rubber boot systems

When It Gets Cold
--Use lighter oil
--Expect control cables to be slack.
--Check breather tubes for frozen condensation
--Use pitot heat to check for ice in pitot tube
--Keep a full charge in the battery
--Consider the use of Prist to prevent fuel icing
--Remove pants with snow on the ground.
--Take our time and do a complete preflight
--Carry a winter survival kit.
--Carry bright plastic marker material
--Keep your warm covers in arms reach.
--Have a carbon monoxide monitor
--Preflight inside the hangar
--Check hoses for flexibility and security
--Check tires and pressure
--Wipe the propeller with anti-ice fluid
--Preheat engine and cockpit
--Avoid hand-propping
--Give the engine plenty of warm-up time
--Slow to very slow taxiing
--Keep weight off nose wheel
--Avoid downwind taxiing
--Consider not retracting gear.
--If you use heater, open the air vents.
--Avoid snow and ice when landing
--Reduce takeoff roll by using flaps
--Stay in ground effect until Vx.
--Monitor flight watch to keep track of the weather
--Any flight into icing is illegal.
--Fly with pitot heat on.
--Climbing is your first choice when in icing
--Avoid steep angles of attack when climbing to avoid icing under flying surfaces..
--Tops of clouds containing ice are higher near the center of the low-pressure area.
--Don't use your autopilot in icing conditions
--Don't delay declaring an emergency
--To descend keep power up to insure engine warming
--Use full carburetor heat to enrich mixture
--Avoid using flaps but increase descent speed
--Blowing snow destroys depth perception
--At -30F ice fog will form over the runway
--Make approach 20/30 knots faster than usual when carrying ice
--Use flaps unless airframe icing exists.
--Make soft field landing with power on.
--Avoid braking on rollout
--Keep full fuel aboard
--Cover engine, vents and pitot.
--Consider draining oil or light in engine compartment
--Always shutdown using mixture

Use of electric hair dryer to warm engine during cold weather.

Winter Flying 
---Do not ever hand prop an aircraft in the winter for many reasons ---Warm up the cockpit before takeoff if you want to rely on your instruments 
---Expect stronger en route headwinds and crosswinds on landing ---Beware of tendency to over-prime in cold weather which is a fire hazard (review fire checklist) 
---Snow covers most landmark references used in flying 
---Check with destination airport for runway snow conditions since NOTAMS may not be current. 
---Dress for survival and have a winter survival kit.

Icing in Brief 
---At first sign of icing use your escape plan made before takeoff ---Check your pitot heat during preflight 
---Turn your pitot heat on BEFORE reaching z-level 
---DO NOT climb at high angle of attack to get above z-level ---Find out if the warmer air is above or below the z-level 
---Make sure your aircraft can climb above the z-level. 
---If you are on-top make sure you are going away from the center of the low pressure where clouds are higher 
---Give an icing PIREP as soon as it occurs 
---Look into the icing history of your aircraft type 
---Any landing made with possible ice in the tail should be a fast; no-flap, no-flare landing

Altitude Lower than Indicated
The Question

Under what conditions will true altitude be lower than indicated altitude?
The answer is:
Colder than standard temperature.
Both temperature and density contribute to pressure, but the altimeter measures only pressure. In contrast, the airspeed indicator and the wings respond to density rather than pressure. That's why conversion between IAS and TAS depends on density altitude rather than pressure altitude; more critically, it's why aspects of airplane performance--such as distance required for takeoff or landing--depend on density altitude rather than pressure

I remember struggling with that question years ago when I was studying for the test. I got a great explanation from somebody here on the net (I've unfortunately long since forgotten who). I'll try to pass that explanation on to you without screwing it up too much.

Pressure is force per unit surface area. Normal atmospheric pressure at the surface is about 15 lbs per square inch. All that really means is if you drew a square one inch by one inch on the ground, then took all the air in the column above that square inch all the way out to the edge of the atmosphere, it would weigh 15 lbs. Now, get in your airplane and start climbing (be careful to stay within that 1 square inch column, so you'd better use a very small airplane). When you get up to about 7000 feet, roughly 1/4 of the mass of air in that column is below you, and 3/4 is above you. The pressure is thus 3/4 what it was when you were at sea level, and your altimeter displays this as 7000 feet.

Imagine you're now mounted on the top of a 7000 foot high pole, so you stay at a constant altitude, and start to cool down the atmosphere. As the column of air gets cooler, it contracts. The column that used to be 100,000 feet high is now only 90,000 feet high. Assuming it contracted uniformly, instead of 75% of it now being above you, only 68% is above you. Since the pressure you feel is just the weight of the column of air above you, you now feel less pressure, and your altimeter now reads a higher altitude.
Roy Smith

You're thinking in terms of *processes* that *change* the density, temperature, or pressure of the air. But that's not what the nonstandard- temperature altimeter-error is about. Rather, it applies even when the air is in a constant state. When the airplane is on the ground, you adjust the altimeter according to the current pressure. The altimeter then should indicate your actual altitude. Temperature doesn't matter; density
doesn't matter; even pressure doesn't matter, because *whatever* the pressure is at the moment, you set the altimeter's Kollsman wheel to make the altimeter associate *that* pressure with the current altitude. (Of course, that's not exactly the procedure you use in real life. At a controlled field, you set the altimeter according to the current ATIS, which may be a little out of date, so the altitude might not be exactly right.)

Then, when you take off and climb, the altimeter tries to guess the change in altitude based on the change in pressure. It's designed to use the standard lapse rate for that guess (about 1" per 1000'). Colder air is more compressed, so its lapse rate is greater than the altimeter's guess, so the altimeter thinks the increase in altitude is greater than it actually is, so you'll be lower than the altimeter says you are. Instead of taking off and climbing, suppose you take off and *descend* (which is possible if you start at a field on a mountain, for instance). In that case, on a colder-than-standard day, you'll actually be *higher* than the altimeter says you are--because, once again, it will think the *change* in altitude (in this case, a decrease in altitude) is greater than it actually is. So the "colder implies you're lower" rule of thumb isn't even always true; if you've descended rather than climbed, it'll be just the opposite, even if the temperature is still far below standard at your new altitude.

Thermal Conductivity of Aluminum and Composite Aircraft
Information regarding the thermal conductivity of aluminum versus fiberglass airplanes, especially as it relates to ice and icing conditions.

I replied with my following experience this morning, as I began
preflighting my trainer for my lesson:

"Michael, I am training in a Diamond DA-20 C1, incidentally, the only composite airplane on my flight schools ramp. I am flying in upstate SC. This morning, at 8:15 the top surfaces of the wings on the C1 were iced significantly, as was the nose and fuselage (tail boom). Outside air temp was 41*F/Overnight low was 40*F. Plane is tied-down, morning sun was directly on wing surfaces, no intervening shadows. My lesson was delayed, of course.

Curious, I checked the other planes on the ramp-all of which are aluminum. NONE had icing on any surface. Through a very unscientific "hand touch" test I determined the composite surfaces "felt" much
colder than the aluminum surfaces.

I would be very interested in learning more about the heat/cold transfer dynamics of aluminum versus composites. Pure speculation though, I would bet from my limited experience that the composite will ice faster or retain ice longer than similarly exposed aluminum. But, there's always someone who knows more about it than me-so maybe they will chime in."

So, I did some research and found the following thermal conductivity values (Note these figures are for a standard temperature of 25*C):

Aluminum, Pure=237 watts/meter*Kelvin
Fiberglass, Paper Faced=.046 watts/meter*Kelvin

So, what I should have inferred from my non-aviation experience with these materials is confirmed by the above thermal conductivity values.

That is, aluminum is a good heat conductor-it can either gain or lose heat very quickly. Fiberglass on the other hand is a good insulator. It does not lose or gain heat very rapidly. Thus once "set" at a
temperature, it will tend to remain there longer than aluminum.

Therefore versus fiberglass the aluminum surfaces will cool to icing temperatures faster, and conversely will heat to non-icing temperatures faster. The composite will cool more slowly,
but once cooled, will retain that temperature much longer, meaning like I discovered this morning, my composite plane will/may be iced when the Cessnas, Pipers and Moonys won't.

During the preflight "Hand Checking Of All Surfaces" has added meaning for a composite driver

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