Best method to de-ice (de-frost) wing?

4 Answers

1. 
   

   
   

   Paul Tocknell on Dec 14, 2010

   Several good questions here.  

   Let me recommend three good resources for you to read before answering your questions.

   • AC 91-74 Flight in Icing Conditions
   • AC 135-17 Pilot Guide: Small Aircraft Ground Deicing
   • AC 20-117 Hazards Following Ground Deicing and Ground Operations in Conditions Conductive to Aircraft Icing
   • AC 91-51AEffect of Icing on Aircraft Control and Airplane Deice and Anti-Ice Systems
   • Aircraft Icing Tutorials / Modules developed by NASA

   You should never take off with frost on your wings.  Recent studies have shown that even light amounts of frost can have serious detrimental effects on lift. 

   The absolute best and easiest way to “de-ice” your wing from frost is to warm it up in a hangar if one is available. Once the frost starts melting, make sure to wipe down the wing with a towel or chamois so it doesn’t re-freeze in critical areas once you take it out of the hangar.  You can also arrange with your FBO to apply de-icing chemicals (Type I, II) but that can be very expensive.  

   Pitot Heat:  As a general rule, I use it any time I’m in any kind of visible moisture regardless of the temperature.  You never know where you might pick up icing.  I’ve picked up serious rime ice on the edge of a summer thunderstorm once.  Many airplanes have been lost (I know one personally) because the pilot simply forgot to turn the pitot heat on.  Most “large” airplanes make the pitot heat an yellow item on the annunciator panel which means it is required to be on for every flight. 

   If I find frost on my wing during preflight, then yes, I would use pitot heat during the taxi out to make sure the pitot tubes were clear.  Taking off with a frozen pitot tube will happen at least once to you during your flying career…just hope it’s not into solid IFR!  

   I leave you with the immortal truths of Osborn:

   

   If you are having a hard time reading the caption to this Robert Osborn illustration that appeared in FAA Aviation News, it says “Your lift can be lost to that old devil frost”.  Make sure you always have a CLEAN WING before takeoff.  No exceptions!

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   Lance on Dec 15, 2010

   As usual, everything Paul said is right on.  I just wanted to add a few things I have picked up from Alaska winters.  Obviously gets very cold in the winter and we have a fair amount of snow and frost to deal with.  Snow, absolutely none is allowable, however frost that fits between the wing covers and the wings is typically considered flyable.  The other thing you want to watch for is whether conditions aloft will allow the frost to sublimate off as you are flying, (same principle as to why if you get into icing conditions descending is not always the only solution).  Also the way most pilots up here clean frost and excess snow off of their wings is a clean, soft bristle, push broom, since hangar space comes at a very high premium.  Hope this helps.

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   Tracy Rhodes on Dec 18, 2010

   I’ll third Paul’s answer and add a few items of interest.
   Transport category aircraft can actually take off with a little frost on the wings – but the catch is that it can only be on the bottom of the wing. The fuel left in the tanks after a long flight can often be extremely cold. If the destination airport is in a humid location it is not unusual for the humidity to condense and form frost on the bottom of the wings where the fuel tanks are located. A thin layer(1/8″) in those locations is acceptable – but none is acceptable on the top of the wings, tail or engine inlets.
   It is also permissible to have a thin layer of hoar frost – thin enough to see through – on the top of the fuselage as long as it doesn’t extend down the fuselage as far as the windows. If it does, the plane must be de-iced. Being practical, if it’s on the fuselage it’s probably on the wings and the plane will be de-iced ‘just in case’. 
   Transport aircraft turn on the pitot heat before engine start and leave it on until engine shutdown. Additional heat to the engine inlets and the wing leading edges is applied if there is visible moisture and the outside temperature is below 10 C(50 F). 
   The first question at the hearing will be “Why didn’t you…” 

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   Jerry Hope on Jan 07, 2011

   I defrosted an airplane one day by parking it behind a small jet and  it’s engines at idle thrust. The whole plane was clean in a few minutes, but the catch is how often is this available as most jets fire up and leave. Naturally I had the pilot’s permisson and briefed him that I was taxing around behind him at at safe distance and to keep power at idle. The exhaust fumes were a little strong!

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