Tips For Flying in ICE

[avbug]

Sublimation (which is a form of evaporation whereby the solid bypasses the liquid state and becomes a gas)will help erode any ice in clear, colder temperatures aloft...

Don't count on that. Ever. The ability for that to happen is largely proportional to the relative humidity at altitude, but it may never sublimate. If it does, nice for you...but don't ever count on that. I spent nearly three hours one day last week working in and out of weather in conditions very conducive to ice formation. I had nearly three inches on unprotected areas, and didn't shed any until descent to lower warmer temps in the clear. Even then, we were still shedding ice on final...in the middle east. It's dry here, too. Very dry, with a very wide temp/dewpoint spread at altitude, but outside the cloud, we didn't see any effects of sublimation.

 

[time builder]

Anyone else have much experience with prop anti-ice affecting their DG/Compass? I'm sure that's another good topic for discussion with icing conditions.

 

[avbug]

Why would propeller ice affect your gyro or compass? Are you talking about electrical boots interfering with the compass? That's possible, as will electric NESA type windscreens, hotplates, and all sorts of other electrical devices...but the ice shouldn't have any effect.

Flight in dry ice crystals can cause st. elmos fire and static discharges, which can affect your compass, but should have no effect on your gyros...especially air driven uncompensated gyros.

I don't think I've ever heard of ice on a propeller affecting a gyro or compass. Can you provide some detail?

 

[time builder]

Right, it isn't the ice, but high electrical loads in the vicinity of the cockpit throwing off the magnetic field of the compass. Now that you mention it, I believe the electric windshield heat threw it off too.

 

[avbug]

The compass should be calibrated with everything on, or at least everything that is expected for most phases of flight. Having the wiskey compass go to la-la land when electrical fields are introduced around it is normal, because all electrical fields produce magnetic fields, and the compass responds to magnetic fields. This will occur when you turn on the systems, without regard to the presence of ice.

Your gyro should not be affected in any way.

You'll likely see the compass moving around, not just in error by a certain amount, because with electric blankets and electric prop boots (and to some degree, windscreen protection), will cycle on and off in stages. One element will be energized for so long, then it goes off and another is energized, and so on. You can see it cycling on your ammeter, and you will probably see changes in the compass that coincide with the spikes or movements on the ammeter.

 

[Hook 'Em Horns]

Nothing to add about flying in ice, but when I was at AirNet we were to cycle the boots and all other anti/de-ice equipment before the first flight during the run-up. This was done all year long to prevent the boots from becoming brittle due to lack of use. A good idea.

 

[sleddriver71]

I know "new research" says that we're supposed to cycle the boots continuously when in icing conditions and that ice bridging is a myth. I would listen to people who fly in areas conducive to icing and those that basically have a lot of experience flying in ice. I flew out of the Seattle, WA area for several years, crossing the cascades frequently. I can't tell you if ice bridging is a myth or not but it doesn't matter at all. What I can tell you from my experience is that blowing the boots with a very thin layer of ice will not get rid of the ice. They teach at SIMCOM that ice bridging is a myth and that waiting to accumulate ice before blowing the boots is not necessary anymore because of the way boots are designed. That is bull loney! I should have known not to listen to someone in Orlando, FL telling me how to deal with ice, all his knowledge came out of a book and mine came from the pacific northwest and the ice machine known as the cascade mountain range. I don't care what the "latest" research says, I know what works and so does anybody who has a good deal of experience flying in icing conditions. Of course it is a good idea to get out of the icing conditions as soon as possible, but it is a BAD idea to immediately cycle the boots as soon as you get the first indications of ice. I flew Chieftains, Senecas, and 400 series Cessnas, and I would never blow the boots until I lost 10-15 kts of indicated airspeed.

 

[avbug]

Ice bridging is definitely not a myth.

I don't know about looking for a performance decrease, but at least a quarter inch or more of ice ought to be present...and you need to consider the type of ice. If it's soft ice that lends to bridging, more is needed before breaking it free. If it's hard glaze ice, then you may be able to crack it sooner. The rate and way in which it's accumulating is also important; if you're briding it out by popping the boots, and it's accumulating rapidly while the boots are out, you can develop a bridge that the next boot cycle won't break.

We ended up yesterday with a couple inches we couldn't get rid of after only three passes through a relatively benign level 2 cell...and it most definitely didn't sublimate in the clear air outside the cell (even with extremely dry air). We had to descend to get rid of it.

 

[Lead Sled]

As per the norm, Avbug nailed it. However, you're probably not going to follow his advice so I'll add another suggestion - get a hold of a copy Weather Flying by Robert Buck and read it cover to cover a few times. You will probably be able to find it at one of the larger book stores and it may even be in your local library.

Icing is one of those things that can kill you. I had a good friend of mine get killed in a known-ice certified light twin while "playing in the snow". Respect it.

LS

 

[sleddriver71]

As per the norm, Avbug nailed it. However, you're probably not going to follow his advice... Icing is one of those things that can kill you. I had a good friend of mine get killed in a known-ice certified light twin while "playing in the snow". Respect it.

LS

Thanks for the information on the book, I will get a copy of it when I can. I am wondering about your comment, "However, you're probably not going to follow his advice..." What are you referring to? If you read earlier posts in this thread you might notice that Avbug and I are not in disagreement, so I'm not sure what you're referring to.