Date: 201501
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Turbulence; Icing; Rain; 0
Light: Night
Aircraft: Aero Commander 500 Series
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Taxi
Reporter function: Single Pilot; Pilot Flying; Captain
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Human factors: Situational Awareness
Anomaly: Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; General Declared Emergency
Contributing factors: Human Factors; Weather
Primary problem: Ambiguous

Narrative: On January 2015; between XA:00 EST and January [next day]; XB:00 EST; an emergency was advised by Air Traffic Control for Aircraft X; an Aero Commuter 500 due to my need to escape an encounter with severe icing. The following is my account of the event; to the best of my memory. After rechecking the weather and NOTAMS at ZZZ1 and ZZZ; I started the aircraft at XA:27 EST. While taxing to runway 23; I turned the TKS system on to the normal setting and noted that the high pressure light was bright yellow. I contacted Center and obtained my clearance. I was cleared as filed; up to 8000 MSL. Prior to my departure; I did one last check of the weather at ZZZ1 and though the ceiling had lowered from the time of my arrival; the temperature was a few degrees above freezing. ZZZ was reporting marginal VFR with 10 miles of Visibility; scattered clouds around 1700 AGL; with overcast around 2000 AGL. I departed at XA:31 EST.I flew the published departure which is a climbing right turn to R270 off of ZZZ1 to 4400 MSL then on course. At 4400 MSL I contacted Center. After several minutes they responded '[Aircraft X]; radar contact; climb to 8000; precede direct HVQ.' My climb was slow and it was difficult to maintain heading and airspeed due to moderate turbulence and a 40+ kt headwind. After passing through 5500 MSL I noticed my groundspeed was 97 kts. Knowing that the winds were stronger above 6000 MSL; I requested from Center to level at 6000. After 4 or 5 minutes at 6000 MSL I noticed my airspeed had dropped from 170 MPH; to 165 MPH. I then took my flashlight and shined it on the wings. The spinner had roughly 2 inches of Rime ice; the props were starting to coat with ice from the root to the edge of the ice strip; [and] the wings were covered from the top to the bottom of the leading edge with about an inch and a half of Rime ice. While inbound to ZZZ1 from ZZZ2; I was able to get on top of the clouds at 10;000 MSL. It was clear above 10;000 MSL to the stars; with negative ice. This was my first out. Also; while inbound to ZZZ1; the freezing rain and sleet turned to rain only while I was passing 4;800 MSL and ZZZ was marginal. That was my second out. Knowing that the wind speeds were higher above 6000 MSL; and seeing how much ice had already accumulated in the amount of time it took for me to climb to 6000 MSL; I determined that the amount of time it would take me to climb to 10;000 MSL; and the rate of which I was accumulating ice; I would not be able to make it to 10;000 feet. At this time I elected to go to my second out and turned the TKS to Maximum. I asked Center how low they could get me and informed them I was picking up ice at a rate faster than I could shed it. The controller then said the lowest he could give me was 5900. I told the controller that I would take it and started down the one hundred feet. The controller then said he could get me lower if I flew a 270 heading for 15 miles. I was hesitant to take it because I knew it would lengthen my time enroute to ZZZ but decided to take it after seeing that I was still accumulating ice on the wings and props. The controller then cleared me to an altitude that was only a few hundred feet less. Then; a minute or so later; he cleared me to an altitude less than 5000 and gave me a heading of 300. Several minutes later he asked for a ride report. I grabbed my flashlight again and checked the wings; props; and spinner. The ice had increased since I checked it last; and since turning the TKS to Maximum. I also noted that my airspeed had dropped 10 MPH in the last 5 minutes. I then explained all of this to the controller and he gave me a heading of 310 and said to contact ZZZ and that they would be able to get me lower. I contacted ZZZ and asked if I could get direct to the airport and asked what the lowest he could give me would be. He cleared me direct and said the lowest he could give me was 3500 feet (I think) but said he could get me lower when I got closer. I took the 3500 and noticed that the airspeed was dropping at an alarming rate. I continued towards ZZZ and a couple of minutes later my airspeed was down to 129 MPH. I then told the ZZZ controller that I needed lower. It was then that he [registered] me [as] an emergency and gave me a descent to 3000. I accepted the clearance and went down to 3000. A few miles further the controller gave me 2200 MSL and I descended. The controller offered me an altitude that would've been 50 feet above the mountains; which I think was 1700 MSL; but I told him I was not going any lower until I was within 10 miles of the airport. Knowing that the temperature at ZZZ1 was above freezing and the elevation is just under 3000; along with the fact that ZZZ was reporting overcast above 2000 AGL and temps above freezing; I thought I would get out of the ice faster than I did. However; it was not until I got a visual of ZZZ that I began to shed the ice. Normally; when the ice begins to come off it sounds like one of the switches on the overhead panel being turned off; or like a circuit breaker popping. This time it sounded more like cannon balls hitting the side of the aircraft. When I was about seven miles south of ZZZ; I was able to call the visual. It took 3 6 second bursts of TKS on the windscreen; and until I was short final for runway 23; for the pilots side of the windscreen to clear. By the time I landed; most of the wings were clear. I landed in ZZZ with no flaps and long at XB:23 EST. The tower had alerted the emergency trucks and they were waiting for me. After I had the aircraft under control on the runway the tower gave me taxi instructions. The trucks followed me to parking. After parking and shutting the aircraft down at XB:24; I got out and was met by the emergency responders. Because the copilots windscreen and the nose were not touched by the TKS; they still had substantial build up. One of the responders asked if the same amount of ice that was on the nose and windscreen was on the wings and I told him yes but it was worse. He then said that was the most ice he had seen on an aircraft that landed. I then answered some questions about my flight from the head responder and gave him my personal information; certificate number; and phone number. I then called my Chief Pilot.




Synopsis: Aero Commander 500 pilot reported encountering 'severe' icing conditions that resulted in greatly decreased airspeed.