Icing encounter

[carusoam]

Some of the quirky and not so quirky things that start ice accumulation....

• Moisture
• Temperatures below freezing
• existing ice crystal structure to build on
• Impurities, another thing that allows ice to start building its crystal structure...

Once the accumulation starts, super cooled, pure water, loves to freeze on the increasing ice surface area....

Airflow around a wing minimizes the immediate build up, that the leading edge starts to see...

weirdest ice build up I have seen on my M20R... a small horn that grew straight out in front of the spinner’s tip. An inch or two long...less than 1/4” in diameter.  Occurred during approach in IMC.... spinning at 2400 rpm or so...?  Witnessed on the ground after taxiing in. 

Direct impact vs a glancing impact probably has something to do with where ice collects first... amount of time is important here...

Water actually takes time to freeze. Parts of a second when conditions are right... time to splatter, run back, and other things...

water droplets have momentum and take time and effort to go around things.

under the right conditions, a simple wire antenna collects ice easily.  The air flow doesn’t move much around the wire and impact with the rain is unimpeded...

Keeping ice crystals from starting to form would be key to designing an anti-ice coating.... super clean, hydrophobic, surface...

All that thought reminds me of plastic wrapping a plane...  we have a guy.... hey @ragedracer1977,  how well does water stick or run off a good vehicle wrap?  Any different than automotive paint?

PP thoughts only, not a weatherman or ice expert of any kind...

Best regards,

-a-

[N201MKTurbo]

1 hour ago, carusoam said:

water droplets have momentum and take time and effort to go around things.

under the right conditions, a simple wire antenna collects ice easily.  The air flow doesn’t move much around the wire and impact with the rain is unimpeded...

Awesome! Somebody actually understands icing!

Same reason dirt collects on the leading edge of fan blades.

[ShuRugal]

On 3/14/2018 at 4:56 PM, jaylw314 said:

Thanks, I need to get past the dogma I have in my head of "IFR=good, VFR=bad"

IFR = "I Fly in Rime+"?

[211º]

Thanks much for the write up.


Sent from my iPad using Tapatalk Pro

[M016576]

12 hours ago, cliffy said:

On the early flat windshield Boeings (727, 737, 707)  your first indication of icing would be on the axle nut of the windshield wiper. Ice would start to build there and it was visible right in front of your eyes. I've seen it 3" out into space from there.

Actually one thing most of you will never get a chance of seeing is St. Elmo's Fire. Quite an experience at night up high. Actually used to bring the FAs up front to see it. 

Oh, wait, I'm day VFR now and enjoying it!!  :-)

I’ll never forget the first time I saw St Elmo’s Fire- it was at night off the coast of San Diego, I was in a F-18C... the whole lower front portion of the windscreen looked like.. well.. it was on fire! At first I thought WTF?!  Then realized what it was...  Some awesome events to behold out there in the friendly skies.

[M016576]

To the OP- welcome to winter in the PacNW.  Living up here has its perks- but winter (IMC) flying almost always carries icing risk with it.

high MEA’s mean you’re pretty much always above the freezing level.

I have a TKS missile, which has the power to get me up into the high teens, and the TKS to help me in the event of an icing encounter.  My planning process though has me looking very carefully at cloud tops and bottoms. 

I don’t feel compelled to fly IFR very often- and pretty much never do in the winter,  part of the reason for that may be that I’m able to maintain currency during my “day job.”  

Don’t feel like you NEED to file IFR just because you have the instrument ticket.  Flying VFR can be safer, faster and more fuel efficient, especially in the conditions you describe.  Where ATC is restricted with MEA’s and traffic, you can duck below cloud decks and maneuver left and right of course while VFR to avoid buildups.  I’ve heard some pilots say that they fly IFR do they “don’t have to worry about traffic.”  That’s not necessarily true- if a pilot is VMC and on an IFR flight plan, they still have the responsibility of looking for traffic and avoiding it if it’s a factor.  Regardless- IFR is a great tool, but it’s just that, a tool- use it when it’s appropriate for your mission, but don’t feel like you MUST use it at all times.

the only thing I’d mention in your decision making process is this: in an unprotected plane, I would not climb out of known VMC, into sub-zero clouds, looking for a top, even if there are no pireps of icing.  Around here you will almost certainly pick up some amount of ice doing that, unless you’re well below freezing (-15C or lower).  If ATC needs you to climb for a MEA, I’d rather cancel and stay where I’m legal and safe.

casual observations flying in this area (K-Falls, LKV, MFR, BDN, RDD) over the past 6 years-

most icing I see occurs between 8-12K, however I’ve seen some buildup as high as 16k.

mostly light-moderate rime

Ive seen heavy once or twice around here- and it fodded out several turbine motors, requiring very expensive inspections and imparted stator blade damage to the compressors... even with the engine heats running.  My best estimation is that  TKS would have been quickly overwhelmed by that day’s icing.  That was at 16-ish K.

the worst icing seems to occur over the lakes, or over the mountains, where the moisture gets pushed up into the freezing layer.

if it’s snowing on the ground, more often than not the tops are fairly low (10-12K).

if you are above the clouds and see a “halo” around the shadow of your plane and freezing conditions abound below, you’ll probably see some ice.

a motor is good. A turbo charger is nice, a turbine is better, afterburners are the best. Unless you’re low on fuel. In which case being on the ground is the best.

realize that all I’ve mentioned above is just some casual observations from flying in this area, and flying through some pretty gnarly weather both professionally and personally over the years.  The FIKI systems are nice, but they have limitations too- vary your risk tolerance based on your skill set and don’t be afraid to dial that risk level back if you’ve got passengers on board. 

Stay safe out there!

Edited March 21, 2018 by M016576

[jaylw314]

6 hours ago, M016576 said:

the only thing I’d mention in your decision making process is this: in an unprotected plane, I would not climb out of known VMC, into sub-zero clouds, looking for a top, even if there are no pireps of icing.  Around here you will almost certainly pick up some amount of ice doing that, unless you’re well below freezing (-15C or lower).  If ATC needs you to climb for a MEA, I’d rather cancel and stay where I’m legal and safe.

Thanks for the comments!  In retrospect, I still have this safety-blanket sense of "if I'm IFR, someone's watching me in case I have an emergency."  Of course, staying IFR almost got me into an emergency, and I could keep VFR flight following anyway, but it's all psychological.  I had plenty of room and space to go under or around if I made the decision earlier.

[Aviationinfo]

Great writeup and frankly the decision making wasn't poor by any stretch.  One thing to keep in mind---deviations off a more direct path make less of a difference time wise on a long trip than they do a short trip, because they are hopefully a smaller percentage of the total distance.  Put another way, if you have a long way to go, it matters less in terms of miles travelled if you go a long distance out of your way to stay VFR and avoid ice, than it does over a shorter distance.  On an 800NM trip, 100 additional miles travelled is 12.5% of the total distance.  On a 500NM trip, it's 25%.  Just to put things into perspective a bit. (It's always worth any deviation to avoid ice in a single engine airplane, but we all like to fly those perfect great circle routes when we can.)

I always appreciate it when people write about what they perceive as their mistakes so we can all learn. Thanks!

[Mooney in Oz]

A lot of excellent advice contained within this thread that doesn't leave much for me to add. I fly a heavy turboprop for a living up to FL250 and therefore above freezing levels almost every time.  When ice starts to form past moderate intensity we get the hell out of there, despite having good anti and de-ice capabilities that more often than not results in a descent rather than a climb.  Although we don't have the high lower safes that you folks have to endure.

I recall my first encounter with St. Elmo's fire was many years ago when I flew a Piper Chieftain in cloud with CB's in the area.  A bright blue jagged line of electricity flowed inward left to right along the base of the windscreen toward the edge then a vertical path that ended at the magnetic compass.  It looked magic.  Only about 3 times in my 30 year career have I encountered this. 

Victor

[PDXBravo]

On 3/15/2018 at 4:58 PM, rpcc said:

Great post btw.  What do you consider your limits for the top of weather you are comfortable with in the bravo?

I can go up to 18,000 with an O2 cannula, 75% of the time, that gets me on top without needing to wear the full face O2 mask.  I've gone up to FL220 for winds.