The Return of Icing Season

It happens every year: G.A. pilots find themselves in icing with no easy outs.  Terrain limits descent, the clouds are too high (or the ice too thick) to climb, and the only way to exit visible moisture is to deviate and land via an impromptu approach ... and the ice continues to build while the decision process churns. 

This scenario should chill any pilot with an imagination good enough to put themselves in it.  Any of us who have had it happen kicked ourselves once we got down and tried to figure out what we did wrong so it never happens again.  It isn't necessary to re-invent this wheel.

Let's look at some resources to help make that determination before leaving the ground.  There are some really good places to go out on the web and I'll show you some of my favorites:

ADDS (Aviation Digital Data Service) is a free website that most pilots are familiar with.  It's easy to use with tabs along the top identifying the various kinds of information available.  The tab labled "icing" is exactly where I go when I want that kind of information. 

First, I look at the Airmets for ice.  The graphic supplied makes it easy to determine if any part of my route will go through an Airmet.  Here's where you can find that graphic: http://adds.aviationweather.gov/phputils/wrap_image.php    It's important to remember, though, that just because you're flying through an area with an Airmet for icing, it doesn't necessarily mean you're in violation of the regs or in danger.  You *must* have both conditions met (temps and moisture) so if you stay out of the clouds and precip, you're fine.  Just because an area has an Airmet for ice does not mean there will be clouds in the entirety of that area.

Here's an example:

The other tool I use on the ADDS site can be found here: http://adds.aviationweather.gov/icing/icing_nav.php   This tool is a little tricker to use but once you've done it a time or two, it makes a lot of sense.  I'll talk about that a little next - it might be useful to you to have both this blog entry and the ADDS page open at once.  You can go back and forth between them to experiment with the settings.

This is really two products: the first is a measure of icing severity, the second is a measure of the probability of picking up ice.  Those are pretty important distinctions.

First, notice that initially this image is a composite image of ALL icing severities from 1,000 feet up to FL300 (30,000 feet).  This isn't exactly helpful since it'll show you ice that might be happening up at 15,000 feet when you don't intend to go even half that high.  You'll see two drop down selections above the image.  The one on the right should say "max".  Click that and pick an altitude at which you intend to cruise and then click the down arrow to view all the altitudes below it. 

The left drop down allows you to view the severity with Supercooled Large liquid Droplets (SLD) which show up as areas of red shading.  SLD is aka freezing rain... and I shouldn't need to tell anybody how bad that stuff is.  You can also select to see severities without SLD, severities only with a more than 25% chance of the ice being there, and severities only with a 50% or greater chance of being there.  I don't really use those other three views... any chance of ice makes me pause and any SLD in my intended altitudes will make me fetch a cup of tea and call it a day. 

Lower in that left drop down, you'll see "forecast icing valid {zulu time and date}"  You can pick a time here and an altitude to the right and see what the percentage chance is you'll encounter any icing.  Astute observers will note that it's pretty common to find a decent chance of icing OUTSIDE an Airmet area for ice.  This fact along with my observations that this tool is usually pretty accurate makes me give it a lot of credence when I'm doing my flight planning

Use these tools and a conservative view when doing your flight planning this winter and stay safe!  If you'd like to have a safe encounter with icing, come see us in Las Vegas where we can put you in our full motion Cirrus simulator and crank up the heat... or crank it down, as the case may be.  http://www.theflightacademy.com/simulator/index.html 

Also, see here if you'd like to read my write up about what to do if you get into icing from last year's blog entry on this subject: http://www.cirruspilots.org/blogs/tips_from_csips/archive/2008/10/13/winter-s-coming.aspx

Safe flying,

John Fiscus

Chief Pilot, The Flight Academy

www.theflightacademy.com