Welcome to Flightinfo.com

  • Register now and join the discussion
  • Friendliest aviation Ccmmunity on the web
  • Modern site for PC's, Phones, Tablets - no 3rd party apps required
  • Ask questions, help others, promote aviation
  • Share the passion for aviation
  • Invite everyone to Flightinfo.com and let's have fun

ICING Questions

Welcome to Flightinfo.com

  • Register now and join the discussion
  • Modern secure site, no 3rd party apps required
  • Invite your friends
  • Share the passion of aviation
  • Friendliest aviation community on the web


Well-known member
Dec 23, 2001
I read these questions in a magazine recently and wanted to see if anybody had some answers/insights. Whenever a technical question gets posted on here it usually starts an excellent thread of discussion.

!. At what altitude will you most likely find the heaviset icing?

2. How does the James Brake Index compare to the MU index?

3. Whats the "clean aircraft" concept?

1) That depends on the temperature and relative humidity, the surrounding airmass, and the overlying airmass. It also depends on the type of aircraft surface, part of structure, texture, preventative measures, etc. It also depends on terrain beneath. I've had some really unpleasant icing down low, and some very unpleasant icing up high. It can occur above 40,000 in visibile moisture, especially near convective activity or orographically lifted air. The worst icing I've encountered has been between 9,000 and 16,000'.

2) I use the payless index. (Walmart index, when casual). I step outside and walk, and if I don't fall on my butt right away, it's not too bad. If I do fall on my butt right away, I fall back to the Sawnut index, which first determines if anybody saw nuthing. If nobody saw anything, it's still not bad. If anybody saw me fall down, I get up and make sure it doesn't happen again. If it's really bad, I resort to th cleat index, occasionally tempered with the cat gravel or salt rock index, and confirm the issue with neosporin and a bandaid. As far as landing...who cares? I'm landing.

3) The clean aircraft concept is A) unknown among normal pilots, but expected by all passengers, and involves no cracker crumbs in the seat rails, a full compliment of airsick bags, and an armed pilot to shoot those foolish enough to track cat hair or dog hair on their airplane.

B) the clean aircraft concept involves keeping aircraft surfaces free of contaminants which might otherwise degrade flying capabilities or performance. It involves ensuring that frost, ice, snow, and other contaminants are not fouling lifting or other flying surfaces, and it also involves a thorough understanding by the PIC of icing, deicing, and prevention. It requires adherence to inspection proceedures, and to taking responsibility for determining that the aircraft is properly cleaned, kept clean, and ready to fly.

A good reference to read on the clean aircraft concept is found at:


while the Avbug always has an interesting answer, I found the most part that , with all the other elements present, the tops of clouds held the worst iceing.

The index I used was if there was enough there to fix drinks with, it was time to be finding somewhere else to fly.

Keeping it simple, the more stuff you have hanging in the icing, the more surfact to catch it.

We actually coated our fleet ( corporate/135) with this wax like sustance that I cannot remember the name of, twice a year. It kept hte paint from decaying and made the surfaces extremely smooth. Bugs and things came off easily, we gained a couple of knots, and ice did not attach to the airframe as quickly.

Latest resources