Icing For Ga Pilots

Icing for General Aviation Pilots Important facts about icing

Date: 1 Jan 06 Rev: Orig

 An iced wing will always stall at a lower Angle of Attack (AOA) and higher Airspeeds  Ask two questions when dealing with icing: o Where is the ice? o Where is it safe?  Icing conditions exists when: o Visible moisture (Clouds or Precipitation) o Temperatures are in the freezing range (+2°C to -20°C)  Icing conditions do not exists when: o Outside of clouds o No freezing precipitation o Temperature outside of freezing range  Important factors to know over the entire route when icing conditions present o Ceilings o Cloud Tops o Freezing Levels o PIREPS o Frontal Activity o As well as AIRMET and SIGMET  A pilot cannot fly into forecast icing, not just known icing  Different kinds of aircraft accumulate ice differently  Aircraft are certified for flight into known icing within a specific envelope  Check De-icing or Anti-icing equipment on the ground when icing may be present during the flight  Keep a watchful eye on the Outside Air Temperature (OAT) gauge  When flying and need to change altitude or course due to icing use “IMMEDIATE” to help the controller understand the situation  Also tell them you can accept changes in heading to help the immediate change in altitude  Try to get out of icing as soon as possible in aircraft without any icing equipment  There are Five (5) outs to help you safely get around flying in icing o Climb → Get to colder temperatures where icing may not be present  Be aware that cloud tops can hold some of the most hazardous icing conditions o Descent → Get below clouds where icing may occur or get into warmer temperatures  Be aware that the lower you go can decrease your distance above the ground o Continue → If in the process of exiting icing conditions o Divert → circum navigate the icing conditions o If all else fails DECLARE AN EMERGENCY  It will increase your options that ATC can help you or that you can do  GET OUT OF FREEZING RAIN AND FREEZING DRIZZLE IMMEDIATELY o No aircraft can handle a moderate amount of accumulation due to freezing precipitation  If you are in icing and ATC cannot get you out of it quick enough DECLARE AND EMERGENCY  Make PIREPS (Pilot Reports) to help ATC know and other pilots of the conditions at that time o There is a small problem with icing reports, they are subjective due to the experience of the pilot and the type of aircraft  Don’t be afraid to ask ATC for PIREPS  Report the absence of icing when forecasted  There are Three (3) kinds of icing For reference only, does not replace any government approved publication.

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Icing for General Aviation Pilots Important facts about icing

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Date: 1 Jan 06 Rev: Orig

o Rime → has a milky look (like that of a freezer that needs defrosting)  Conforms to the airfoil  Accumulates in a pointed shape o Clear → transparent look  Rough accumulation  Forms horns which dramatically increase drag o Mixed → clear in the center with white on the sides  Could have any of the above mentions qualities There are Three (3) amounts of accumulation o Light → ¼ inch accumulation within 15 – 60 minutes  occasional use of icing equipment o Moderate → ¼ inch accumulation within 5 – 15 minutes  Frequent use of icing equipment o Severe → greater than ¼ inch accumulation within 5 – 15 minutes  Exit immediately, no aircraft is certified for flight in severe icing Give PIREPS Interpolate PIREPS o If a B737 is climbing to altitude and incurs light icing a C182 may incur severe icing due to duration within the icing altitude o Each aircraft will accumulate icing differently due to design and icing equipment At the first sign of icing turn on all icing protection o Window Heat o Prop Deice o Fluid Surface De-icer o Pneumatic Boots o Pitot Heat (if not already on) Keep wings clean Ice bridging only affected early boots when times for inflation and deflation were increased Previous pilots were told to wait until at least a ¼ inch was on the wing, no longer required With modern boots there has never been a case when ice bridging has cause and accident Struts, OAT gauge probes, and other similar size items pick up ice before wings including tail surfaces Test conducted by NASA on several modern airfoils demonstrated that, in some instances, exposure to clear icing for 2 minutes could double the drag, reduce the maximum lift by 25-30% and reduce the critical angle of attack by 8 degrees (which would correspond to a substantially higher stall speed) NASA saw a 30% increase in drag on the aircraft due to accumulations in areas without icing protection When on top of the clouds and you see a rainbow that means that there is liquid water in the clouds If possible hand fly the aircraft through all possible icing conditions Hand fly all approaches in icing conditions Symptoms of a wing stall due to icing o Airframe Buffet o Sluggish or Ineffective Roll Control o Don’t rely on the stall warning horn it may have frozen over due to icing accumulations Recovery from a wing stall

For reference only, does not replace any government approved publication.

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Icing for General Aviation Pilots Important facts about icing

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Date: 1 Jan 06 Rev: Orig

o Reduce AOA o Increase Power o Same as clean wing stall If ice is on the wind it is probably on the tail If increase thrust will induce a nose down pitch it could aggravate a tail stall Symptoms of a tail stall due to icing o Lightening of the yoke especially in the forward direction o Difficulty trimming the pitch o Pitch excursions similar to pilot induced oscillations o Buffet in the yoke only not the airframe Recovery from a tail stall o Pull back on yoke o Raise flaps o Consider reducing power Wing Stall verses Tail Stall o Wing stall  High wing AOA  Slow airspeed o Tail Stall  High tail AOA  Flaps down  Higher airspeed If a an unanticipated movement occurs UNDO WHAT YOU JUST DID If you know you are going to have to descent into icing conditions and the aircraft may not handle it well stay on top as long as possible Keep your speed up! If snowing water is already frozen and ice crystals will bounce off of the aircraft Cycle boots (if installed) at the Final Approach Fix (FAF) to get the best performance out of the aircraft Keep your speed up (stall speed can increase up to 30 knots with icing!) Ice that has little effect at cruise can have a major effect at slower airspeeds When shooting and instrument approach in icing conditions: o Increase speed o Consider reduced flaps o Minimize bank angles due to possible increase stall speed o Consider delaying gear extension until runway is made

For reference only, does not replace any government approved publication.

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