Skylane 182/RG Turbo Skylane/RG
Flight Crew Private; Flight Crew Instrument
Flight Crew Last 90 Days 19; Flight Crew Total 768; Flight Crew Type 491
Situational Awareness
Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Exited Penetrated Airspace; Flight Crew Requested ATC Assistance / Clarification
Human Factors; Weather
After receiving a weather briefing via Foreflight with AIRMET IFR indicating ceilings below 010 FG/BR over a wide area and AIRMET ICE for MOD ICE BTN 100 AND FL240 along the southernmost portion of my route. The freezing level AIRMET's were all well north and/or east of my route. I filed an IFR flight plan via the coastal route due to lower terrain instead of more inland at 9000 feet thinking this would keep me below the icing forecast altitude and would give more options for cruising at a lower altitude should I encounter icing. As it turned out; I did begin to encounter some very light rime icing at 9000 feet about an hour into my flight. The indicated OAT was -1C but I was in and out of the clouds so was concerned but thought if the problem did not get worse we should be ok. ATC then started vectoring me more east of my route and told me to expect 11000 feet for terrain. I questioned that as the highest MEA was only 7700 feet. I also stated I had picked up some light rime icing and might need lower if they climbed me to 11000 feet. They said to make my request with the next sector. After the handoff; they kept me at 9000 feet but in the clouds again I was picking up more rime icing so I requested lower. They said they could only give me higher and cleared me to 11000 feet. This put me in between layers with an OAT of -3C so ice accumulation ceased with maybe 1/4 inch on the very leading edges of the wing and struts and 20 knot reduction in airspeed. As soon as the terrain allowed I requested lower and on reaching 7000 feet all of the ice melted off within a few minutes.What I learned: treat the freezing level as a rough guess and expect icing if the cloud bases are anywhere near the freezing level. Don't count on ATC being able to clear you lower; so file lower in the first place. And; lastly; if you don't have much experience flying IFR in IMC then get a live weather briefing from Flight Service. The output of a DUATS or Foreflight briefing presents far more information than you can make sense of sometimes and a weather specialist would have been very helpful to me in deciding on an appropriate altitude and route.
A C182 pilot filed an IFR flight plan to just below the forecast freezing level and when rime ice started accumulated was initially unable to get cleared to an altitude below the freezing level. Fortunately; a climb got him between layers until the undercast allowed a descent free of moisture.