Date: 201307
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Weather elements / visibility: Turbulence; Convective; 50
Light: Daylight
Aircraft: Skylane 182/RG Turbo Skylane/RG
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
Reporter qualification: Flight Crew Private; Flight Crew Instrument
Human factors: Situational Awareness
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Weather
Primary problem: Ambiguous

Narrative: This flight was on and IFR flight plan in support of a search and rescue flight. The flight was planned; filed; and anticipated to take approximately 4 hours. The departure and destination airports were the same. I had an area of interest to orbit; which was accounted for by fixes used in the flight plan. This report is related to being off an assigned altitude during that flight. Weather over the route of flight was predominantly scattered cumulus. These conditions prevailed over most of the state. VFR conditions prevailed. Bases were around 030-045 MSL and tops averaged from (I'd guess) 100 FT MSL to 160 FT MSL. At the time of loss of altitude I was heading east; there was a perpendicular (northeast-southeast) line of convective activity 30-50 NM ahead of me and slowly moving to the east at 25-35 KTS. I knew about this line and had been monitoring it before my departure. Bases in and around the buildups were between 010-020 FT MSL. Tops for those were over FL250; and were clearly visible. For the most part; NEXRAD was indicating everything I was visually seeing; and like always I was only using NEXRAD for situational awareness. I visually remained clear of any buildups and remained vigilant to not put myself in a position with no outs (in front of a cell; for example.) Enroute I was in and out of the clouds and had a clearance of 090 FT MSL and did not experience any disruptive/convective activity to upset the aircraft attitude beyond normal light chop normally experienced through these types of clouds. I would say 80% of enroute was VMC; 20% was in/out of clouds IMC. As I got closer to significant weather; I requested a deviation from ATC to get around and a better view. I was cleared as requested. After another 20-30 NM; I could then see I was not going to make my intended filed fix (for the orbit) as the weather was still slowly moving out in front of me. This time I requested a hold; and again the request was granted. I flew a standard hold at that position (IFR/VMC) for approximately 30 minutes. As the weather had continued to move out; conditions were looking better to my east. I then requested a clearance and hold at the next fix I had flight planned. Again ATC cleared me to the fix; hold; and provided another further clearance time of +30 minutes. As I was 10 NM from the fix; it could see clouds; but nothing towering or ominous. NEXRAD was also as current (as it can be); and was not indicating any precipitation in front of me. It appeared the next hold would be in and out of some clouds for a brief period. Again; the clouds looked fair at this point. Upon entering the clouds; the aircraft was rocked quite hard. I immediately disengaged the autopilot and hand flew the aircraft for wings level. It was at least moderate chop with significant seat harness pressures; but there was also apparently a significant down flow in the cloud; as I had lost a couple hundred feet in only a couple of seconds. There was no rain or significant moisture (which is why radar had nothing). I then initiated a right standard rate turn back to the west; and reconfigured the aircraft for full prop; full throttle; and slight climb to get back to 090 FT MSL. I then contacted ATC and informed them I was deviating back to the west because of weather. The Controller then stated he/she saw I was off altitude and I informed the controller I was working to get back to 090 FT MSL but was getting rocked around pretty hard. Within 15-30 seconds I was back at 090 FT MSL; but was still in IMC; and experiencing significant upset attitudes. I also requested a block altitude at this point; but ATC could not provide that. I again experienced another down flow (probably the same one I flew through initially); which dropped be back to 085 FT MSL. Again; I configured for a climb and probably only after another few seconds I was back in VMC and out of the convective air; level 090 FT MSL. I then obtained a clearance to another fix back to the west and did onehold there; while myself and crew reassessed our options. At that point; I canceled IFR but maintained flight following. We remained VFR/VMC and were able to get back to 035 FT MSL for the duration of the flight. The flight could have entirely been conducted under VFR conditions. However; with the anticipated increase in GA aircraft coming to the fly-in; my preference was to be IFR/VMC; IFR/IMC; or VFR-on-Top to mitigate risking a near air encounter with another aircraft. I felt with potential ceilings of 030 FT MSL it would be too conducive to many GA aircraft flying at the same altitudes in the same area and considered that in my preflight risk assessment. I still feel that was the right choice (IFR); however; it is very clear that convective conditions are not all that clear; or that cloud conditions can vary significantly; despite their 'look.' I feel I made the right decision to turn back; report my deviation; and to return to known better flight conditions. There was probably no real need for me to press on when I did; after the first hold. I feel I could have made a better decision there. External pressures and weather I feel were factors; but clearly deciding to continue east; was [ill advised.] I certainly never had the intentions of taking on a thunderstorm; or anything remotely close. I am very grateful I can write and share my experience with others.




Synopsis: C182 pilot reports encountering a strong downdraft upon entering a cloud; resulting in the loss of several hundred feet. The reporter elects to make a 180 degree turn while climbing back to 9;000 FT and advises ATC after the fact.