Date: 201710
Local time of day: 1201-1800
Location: PDT.Airport, WA
Flight conditions: Mixed
Weather elements / visibility: Icing; 10
Light: Daylight
Aircraft: Bonanza 35
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZSE
ATC / advisory: Center ZSE
Reporter organization: Personal
Reporter function: Single Pilot
Reporter qualification: Flight Crew Instrument; Flight Crew Private
Human factors: Communication Breakdown; Distraction; Time Pressure; Situational Awareness
Anomaly: Deviation - Altitude Overshoot; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Weather; Human Factors
Primary problem: Human Factors

Narrative: The weather conditions were VFR at Redmond; and along our whole route of flight. Ground temperatures were in the 50's (F). I checked the weather report at Pendleton and Pasco; and both airports were reporting clear conditions (no clouds); and visibility of 10 miles. There had been some puffy white clouds on our way to RDM earlier in the day; that had not presented any problems. I noted the same clouds as we departed Redmond. I climbed to our initial altitude of 9000; but noted that this would put us right in the middle of the scattered clouds along our route. I noted the bases to be around 7000; and was told that the MEA along this initial segment was 7000. So I asked for 11000; and was cleared to climb to this new altitude. I did; and this got us above some of the scattered clouds. But some ahead required very small deviations to avoid. But about 40 nm from PDT; I noted a gray build-up ahead that looked more ominous. I asked Seattle Center if they had any precip/weather on their radar in my route of flight; and they said no. My iPad; which had an ADS-B receiver; did not show any weather either. Since I had previously blown right through the puffy white cloud build-ups; I optimistically hoped I'd be thru this weather in 30 seconds or less. But about 20 seconds after penetrating this cloud; I suddenly encountered a pelting of ice on the windshield. It was loud; and rapid; and got my attention! I knew I couldn't out climb it; and I knew that the bases of the clouds were above the terrain; so I asked for a descent. Seattle cleared me lower; and I quickly began a rapid descent. In my haste; I didn't pull the power back initially; and then had Center calling to verify what type of ice and what the temperature was. I checked the temp and looked at the wings to see what type of buildup I was getting. The outside air temp was in the mid 20's (F); and there was minimal build-up on the leading edge. By the time I answered Center; my airspeed was 10 mph (5 knots into the yellow arc). I quickly pulled the power back; and continued my descent. A wing-leveler autopilot had been in use prior to entering the cloud; and I continued to utilize this to reduce my workload; as I adjusted trim for my descent. As I recall; I was cleared to 6000. Just as I reached 6000; I was able to see the ground below; but was still cruising in the base of the clouds. I reported that I could go VFR under the clouds if I could descend further. I could see the ground clearly enough to see that I was still several thousand feet above any terrain below; and my iPad did not show any rising terrain ahead. The controller as I recall said I could descend; but was concerned about the MEA in this area being 6000. I descended to 5000 and was clear of the cloud/weather; and the ice had shed. I then began a climb back to 6000; as it seemed to me the controller was uncomfortable with me at 5000. Part-way to 6000; he came back on asking why I was changing altitude without requesting this with first. I apologized; and he then cleared me back to 6000. I continued the flight without further issues; and landed 20 minutes later.As I reviewed this flight; the following were the learning points I took away:1. If you see some threatening weather; avoid it! Even if the controller and your weather app don't show it; believe your eyes. 2. Aviate; Navigate; Communicate. If I had followed this age-old adage; and asked Center to 'Standby' when asked about the type of ice; amount; and air temp - and instead focused on my instruments; I likely would have avoided the overspeed situation I got into. Perhaps Center could have asked me to report this information 'when able'; which would have made me feel less like I had to do it right away.3. Note what the freezing level is; and whether it is above or below the bottom of the weather/clouds I'll be flying thru or around. Since the aircraft I fly is not certified for flight into known icing; I need to know before and during the flight whether it is safe to proceed. In this case; the freezing level was above the bottom of the clouds; and the base of the clouds was just at the MEA. I might have been better off going VFR below these clouds; as they were several thousand feet above the terrain; and I would have been in temps above freezing. I've just previously had the impression that I'm safer on an Instrument Flight Plan. But another option in this scenario; is that I could have asked for flight following; and stayed VFR under the weather.4. If in doubt about any instructions from ATC; ask for clarification before doing something. After making my descent to 6000; and then to 5000; I assumed the controller wanted/preferred me at 6000; due to the MEA. But I didn't ask for clarify about this; and began climbing back to 6000; catching him off-guard; as I evidently didn't have permission to change altitude.




Synopsis: Bonanza 35 pilot reported experiencing enroute icing and ATC transmissions that resulted in an overspeed while descending to clear the ice. A subsequent altitude excursion related to the pilot's misunderstanding of the altitude clearance.