Narrative:

I departed ykm airport IFR at XA29Z on mar/thu/94. ATC assigned V4 towards seattle (sea) and I was assigned 10000 ft. After becoming established on V4, I climbed in IMC from about 7000 ft to 9000 ft and emerged VFR and proceeded wbound on V4 with a very light trace of ice forming on the outside air temperature probe on the windshield. The controller at ZSE (120.3) informed me that an airliner had experienced rather severe icing in their climb from sea, and suggested a diversion to the north to join V298 where I would be able to fly at a lower MEA (8000 ft). I was assigned a vector of 310 degrees for intercept and was kept at 10000 ft. There was a significant headwind and, by the time I intercepted V298, the icing had begun to slowly increase. I was given 8000 ft and the ice continued to slowly accumulate, now on the leading edge of the wing and the top of the gas cap. I had been passed to sea approach (119.2) and I informed them of my situation. I asked whether I could get a lower altitude and was informed that there were lower emergency altitudes available but could be used only if an emergency existed. I evaluated my situation as slowly deteriorating and declared the emergency. Approach gave me vectors towards swoqualurie pass which I crossed at about 6500 ft. Proceeding wbound over highway I-90 I was gradually given lower altitudes and, by the time I was over the city of issaquah, the ice began to melt. I was given vectors toward rnt (renton) field and emerged from IMC at that point. Before departing ykm I had a WX briefing and the only relevant PIREP was a jet which reported a 'trace' of 'rime' ice at 15000 ft, reported 20 NM east of sea. Although I knew the potential of ice existed when departing, it seemed like a good decision at the time. In retrospect, I feel it might have been better to remain on V4 at 10000 ft (or even higher) as long as possible with as rapid a descent as possible when located west of the cascades. I feel my decisions in the air (including the decision not to return to ykm, due to the high terrain in each direction) were warranted at the time. I found the sea approach controller to be excellent and am indebted to him for his professional and timely assistance.

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Original NASA ASRS Text

Title: AN SMA GOT INTO A LOAD OF ICE.

Narrative: I DEPARTED YKM ARPT IFR AT XA29Z ON MAR/THU/94. ATC ASSIGNED V4 TOWARDS SEATTLE (SEA) AND I WAS ASSIGNED 10000 FT. AFTER BECOMING ESTABLISHED ON V4, I CLBED IN IMC FROM ABOUT 7000 FT TO 9000 FT AND EMERGED VFR AND PROCEEDED WBOUND ON V4 WITH A VERY LIGHT TRACE OF ICE FORMING ON THE OUTSIDE AIR TEMP PROBE ON THE WINDSHIELD. THE CTLR AT ZSE (120.3) INFORMED ME THAT AN AIRLINER HAD EXPERIENCED RATHER SEVERE ICING IN THEIR CLB FROM SEA, AND SUGGESTED A DIVERSION TO THE N TO JOIN V298 WHERE I WOULD BE ABLE TO FLY AT A LOWER MEA (8000 FT). I WAS ASSIGNED A VECTOR OF 310 DEGS FOR INTERCEPT AND WAS KEPT AT 10000 FT. THERE WAS A SIGNIFICANT HEADWIND AND, BY THE TIME I INTERCEPTED V298, THE ICING HAD BEGUN TO SLOWLY INCREASE. I WAS GIVEN 8000 FT AND THE ICE CONTINUED TO SLOWLY ACCUMULATE, NOW ON THE LEADING EDGE OF THE WING AND THE TOP OF THE GAS CAP. I HAD BEEN PASSED TO SEA APCH (119.2) AND I INFORMED THEM OF MY SIT. I ASKED WHETHER I COULD GET A LOWER ALT AND WAS INFORMED THAT THERE WERE LOWER EMER ALTS AVAILABLE BUT COULD BE USED ONLY IF AN EMER EXISTED. I EVALUATED MY SIT AS SLOWLY DETERIORATING AND DECLARED THE EMER. APCH GAVE ME VECTORS TOWARDS SWOQUALURIE PASS WHICH I CROSSED AT ABOUT 6500 FT. PROCEEDING WBOUND OVER HWY I-90 I WAS GRADUALLY GIVEN LOWER ALTS AND, BY THE TIME I WAS OVER THE CITY OF ISSAQUAH, THE ICE BEGAN TO MELT. I WAS GIVEN VECTORS TOWARD RNT (RENTON) FIELD AND EMERGED FROM IMC AT THAT POINT. BEFORE DEPARTING YKM I HAD A WX BRIEFING AND THE ONLY RELEVANT PIREP WAS A JET WHICH RPTED A 'TRACE' OF 'RIME' ICE AT 15000 FT, RPTED 20 NM E OF SEA. ALTHOUGH I KNEW THE POTENTIAL OF ICE EXISTED WHEN DEPARTING, IT SEEMED LIKE A GOOD DECISION AT THE TIME. IN RETROSPECT, I FEEL IT MIGHT HAVE BEEN BETTER TO REMAIN ON V4 AT 10000 FT (OR EVEN HIGHER) AS LONG AS POSSIBLE WITH AS RAPID A DSCNT AS POSSIBLE WHEN LOCATED W OF THE CASCADES. I FEEL MY DECISIONS IN THE AIR (INCLUDING THE DECISION NOT TO RETURN TO YKM, DUE TO THE HIGH TERRAIN IN EACH DIRECTION) WERE WARRANTED AT THE TIME. I FOUND THE SEA APCH CTLR TO BE EXCELLENT AND AM INDEBTED TO HIM FOR HIS PROFESSIONAL AND TIMELY ASSISTANCE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.