Aviation Notes – Jim's

March 25, 2010

Cirrus Icing Awareness Course Notes

Filed under: — jcramer @ 3:16 pm

Module 1 – System Overview – March 25, 2010

– The new pitot heat switch also heats the stall warning on the opposite wing.

-Don’t use pitot heat for more than 45 seconds on the ground.

-The Normal switch allows for 30 seconds on, 90 seconds off for TKS, while the High switch allows for continuous TKS.

-The Max button (not a switch) provides a 2 minute burst rate of TKS, which is 4 times the normal flow rate.

-The windshield button (not a switch) will shoot a 3 second stream of TKS on the windshield.  It uses a separate pump.  This pump is also used to prime the two main metering pumps, thus, testing it is part of the pre-flight.

Moduel 2 – Preflight – March 25,  2010

-When on the ground, the flaps must be fully extended to test the stall warning.

-Close the door! before testing the windshield system.

-Turn the system on High before doing external pre-flight inspection.

-Taxi with care so that slush doesn’t fly up under the wing and block the TKS tank vent.

The legal limit of minimal TKS fluid for flight is 5 gallons.  That’s AFTER your pre-flight.

-Pre-flight test the system every 30 days!!!  Even if not used.

-Caution when cleaning the panels along the leading edges!  Use soap and water, isopropyl alcohol, or ethyl alcohol.

Module 3 – Flight Planning – March 25 ,2010

-AIRMET Zulu are issued every 6 hours (or when needed) to update potential icing.

-SIGMETs are unscheduled and are for sever icing not associated with thunderstorms.  Any area with a SIGMET for icing should NOT be entered!!

-Close isobars on the surface analysis charts predict lifting and potential icing areas. Fronts on these charts help too.

-White areas on satellite imagery that don’t move in the looping may be ground snow.

-CIP (current icing product) show shading for intensity with PIREPS overlaying the chart.

-PIREP icing symbology: U is trace, U with 1 bar is light, U with 2 bars is moderate, and a U with 3 bars is sever.

-Always concede altitude for airspeed if safe speeds cannot be maintained, due to ice accumulation.

-Never take off with the icing system running thinking it will take off whatever snow, ice or frost has already accumulated on the wings.  You might not get off the ground!

-If you think you’ll need TKS right after take off, start the system before taking the runway.

-If clearance altitude will put you in the ice, ask when higher can be expected BEFORE accepting the clearance.

-In the mountains, avoid flying down-wind of ridges and peaks. This is an area where moisture could have been lifted off the mountain and be a heavy icing area.

-When Descending:  Keep the KIAS below 177 and KTAS 204, otherwise, the TKS might not flow to the top of the wing and only cover the bottom. Also, delay descent whenever you can to stay out of icing as long as possible.

-If told to hold in icing conditions, do NOT lower flaps! And do not exceed 45 minutes in an icing hold.

-When landing with ice still adhering to the plane, limit flap extension to 50%. Approach at 95 KIAS and short final at 88 KIAS.

-Flight into freezing rain or freezing drizzle is prohibited!

-If snow is adhering to the wings during taxi, delay departure until take off without contamination can be accomplished.

Module 4 – SYR-ALB – March 25, 2010

-For ice to form, you must have 1) moisture, and 2) freezing temperatures (2+C to 40-C).

-Types of ice:

*Glaze: +2 to -5, most hazardous!, can form ice horns, slushy.

*Mixed: -5- to -15, combines glaze & rime.

*Rime: -15 to -20, white or opaque, freezes on contact.

-Ice can form in up to -40, but normally you’re safe below -20.

-Stratus Clouds:

*When predicting ice in stratus clouds, look at lifting mechanism such as mountains or fronts or convection.

*Ice in the stratus clouds is most pronounced in the tops.

*They are the most common types of cloud to produce icing during the coldest months of the year.

*A rule of thumb: an altitude change of 3,000′ should be sufficient to get away from icing because stratus clouds are typically layered and can go on for miles.

*Can contain SLD (supercooled large droplets).

-If there’s precipitation on the ground, then there WILL be precipitation in the air.

-Cumulous Clouds:

*Can contain icing throughout the year.

*Can contain SLD (supercooled large droplets).

*Encounters are short in duration, but can be sever.

-Warmer temperatures CAN be higher, especially if they’re above the cloud formation.

Module 5 – BLI to BKL – March 25, 2010

-SAT (Static Air Temperature) is the physical temp of the air the plane is flying through.

-TAT (Total Air Temperature) is the temp of the skin of the plane caused by compression.

-Orographic Lifting – when air moves up a mountainside, it condenses water and creates turbulence.  Can also create SLD.

-Avoid flying along the windward side of the mountain where severe icing and turbulence might occur (though I’m not sure if the leeward side is better for turbulence??).

-Warm Fronts:

*More typical in cold months and more dangerous than cold fronts.

*When approaching in the direction the warm front is headed, the cloud tops will rise. Layers of clear air may disappear & put you in the clouds.

*Warm fronts climb slowly over cold fronts (thus the lifting mechanism) and can production icing condition over 10,000′ thick!

*Freezing drizzle and freezing rain can occur in these cases.

-For the TKS system to be effective, KIAS must be maintained between 95 and 177 knots.

-Trace Icing: activate system on Normal, no other changes needed.

-Light Icing: problematic if over an hour, activate system on Normal, try changing heading and altitude, if not better then exit.

-Moderate Icing: exit immediately, activate system on Normal/High, do anything you can to keep ice from adhering to surfaces, switch to High/Max if worsens.

-Severe Icing: this is an in flight emergency, use High/Max and consider using the parachute, SLD, freezing rain or drizzle, larger droplets will accumulate quicker and more quickly on the aft of the plane.

-If ice is not shedding on approach, perform the Anti-ice System Failure Checklist, limit flaps to 50%, keep approach at 95 KIAS and short final at 88 KIAS.

-If snow is falling that’s granular and dry, moisture in clouds above is unlikely.  If its wet and sticky, you’ll find moisture above.

-Lake Effect can cause heavy precipitation downwind of the body of water as colder air flows over warmer water.  Severe icing is possible!

-Taking off into known icing conditions is prohibited if you have any frost, snow, slush or ice on your aircraft.

Module 6 – JAX to LOU – March 25, 2010

-Cold fronts in the spring can produce lines of thunderstorms with possible icing at the lower levels.  Cold front is pushed above warm air.

-Approaching the cold front, you’ll see cumulous and towering cumulous clouds ahead.

-Towering cumulus clouds with “cap clouds” means lots of vertical inside and should be avoided!

-Weather with tops of 15,000′ can be hazardous.  While weather with tops of 20,000′ ARE hazardous.

-If the TKS system can’t keep the ice from forming, you are in severe icing!  Follow the Anti-Ice System Failure checklist and get out!

-If you try to add flaps on an approach after leaving severe ice, you may have a tail stall which will pitch the nose down sharply and may kill you.  If this happens, retract the flaps!

-Occulated Front is a cold front catching up to a slow moving warm front, squeezing the warm air aloft.

-The frontal zone is always located on the side of the cold air mass.

Moduel 7 – Quiz – March 25, 2010

-The windshield spray cannot be used within 30 seconds of landing.

No Comments »

No comments yet.

RSS feed for comments on this post. TrackBack URL

Leave a comment

Powered by WordPress