Date: 201305
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: Mixed
Weather elements / visibility: Icing; 10
Light: Daylight
Aircraft: Cessna 340/340A
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Commercial
Human factors: Communication Breakdown; Training / Qualification
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors; Weather
Primary problem: Weather

Narrative: I departed...on a filed IFR flight. I climbed to 15;000 FT and was on top of scattered clouds during the first part of my flight. The scattered cloud layer was several thousand feet below my plane and at times clouds rose to within five hundred feet of my altitude. As I proceeded north I could remain above the scattered clouds and see clear areas in all directions. When I neared...100 miles south of my destination; I could see that the clouds were becoming broken and they appeared to also be getting higher. I had plenty of fuel to return to [base] if necessary which is why I had stopped to refuel before continuing to [destination]. When I saw that I might have to enter the higher clouds I contacted Center and requested to start my descent to reach lower altitudes and warmer outside temperatures that would be above freezing. Center said he would start me down further ahead and left me at 15;000 MSL. Several minutes later I entered the clouds and was flying through some of the tops. I noticed some light traces of ice forming on my prop spinners and I realized I should have been firmer in my request to descend earlier with ATC to prevent entering the clouds below the freezing level. I again requested a descent and also report icing conditions to ATC and was then given a descent down to 11;000 MSL where the temperature was above freezing. I continued my flight in non-icing temperatures and landed without incident. My encounter with icing conditions was very minimal and lasted for only several minutes although it should have been avoided all together. The minimum IFR altitudes were all below the freezing levels. Center immediately resolved my situation after I mentioned ice and they are always my best resource outside the aircraft. After reviewing my situation on the ground I realize I had several options that would have prevented this encounter with icing conditions and I will not allow this event to happen again. I could have requested a 180-degree turn before continuing forward into the clouds while waiting for an ATC clearance to descend. I also could have been firmer and told the Controller I needed the descent to avoid a known ice violation and possible icing problems with my airplane. I could have also requested an approach into [alternate] which would have got me below the freezing level before I entered the clouds.




Synopsis: C340 pilot on an IFR flight requested lower altitude to avoid icing conditions; but did not receive immediate clearance to descend. After noting ice on the prop spinners; the pilot advised ATC and was given clearance to descend.