Narrative:

My WX briefing at 9 O'clock local included flight precautions for icing but the freezing level was reported at 13000', 4000' above my flight planned altitude and 5000' above the mtc altitude for V195 at its highest point. This seemed like a safe margin. Also there were no PIREPS of icing. Before takeoff (arcata to nut tree via V27 fot V195 rbl V23 sac direct) I checked with arcata FSS for current WX and the freezing level. It was then reported at 11000', which still did not seem likely to cause problems for flight at my planned altitude. After climbing to altitude my OAT read 3 degrees C, consistent with an 11000' freezing level. After about 10-15 mins at altitude I noticed that I was picking up a small amount of mixed ice on my wings and requested and was given an 8000' cruising altitude. Since the OAT was already above the freezing level I expected that a descent of 1000' would be more than enough to clear the ice. Instead ice began accumulating more rapidly as the OAT remained the same at the lower altitude. After about 5 more mins I began accumulating sufficient ice that I was no longer able to maintain altitude. At this point ice was accumulating very rapidly and my induction air became blocked and my engine started running rough. Still the OAT read 3 degrees C. Finally we broke out between layers at about 7300' and within a minute or two the ice began coming off and we were able to climb again to 8000'. In retrospect I wish I had asked the arcata FSS for PIREPS before takeoff. If I had heard PIREPS of icing I might have chosen a route with a lower MEA. Although I didn't ask, I would hope that in such situations FSS personnel would volunteer such PIREPS to pilots who ask for the freezing level. Once in the air I wish I had turned back at the first sign of icing. At that point I could have made it back to the fot VOR and a lower MEA with no difficulty. By the time I had descended to 8000' and determined that the ice was still building up, it was a shorter distance to tomad intersection than back to yager. Because of this I decided to proceed to tomad. The original decision to continue at a lower altitude was faulty since I did not consider the possibility that ice would continue to build up at that level, let alone the possibility that the rate of build up could get worse. Finally, nothing in my training suggested to me the possibility that I could build up a significant amount of ice with outside temperatures above freezing. Callback conversation with reporter revealed the following: pilot indicates that a check on the static outside temperature gauge revealed that it was off by 10 degrees F. PIREPS were reported en route but were for a higher altitude than reporter was utilizing. Pilot did give a PIREP to ZOA after he regained lost altitude. Counseling conversation brought out the need for more discretion to be exhibited in the choice of arwy and height of underlying terrain so as to have more latitude if a lower altitude is required. Also the use of a 180 degree turn being a smart and easy thing to do.

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Original NASA ASRS Text

Title: SMA PICKED UP UNEXPECTED ICING ON ACFT. ICE ACCUMULATION CAUSED ACFT TO LOSE ALT FROM 8000 TO 7300'.

Narrative: MY WX BRIEFING AT 9 O'CLOCK LCL INCLUDED FLT PRECAUTIONS FOR ICING BUT THE FREEZING LEVEL WAS RPTED AT 13000', 4000' ABOVE MY FLT PLANNED ALT AND 5000' ABOVE THE MTC ALT FOR V195 AT ITS HIGHEST POINT. THIS SEEMED LIKE A SAFE MARGIN. ALSO THERE WERE NO PIREPS OF ICING. BEFORE TKOF (ARCATA TO NUT TREE VIA V27 FOT V195 RBL V23 SAC DIRECT) I CHKED WITH ARCATA FSS FOR CURRENT WX AND THE FREEZING LEVEL. IT WAS THEN RPTED AT 11000', WHICH STILL DID NOT SEEM LIKELY TO CAUSE PROBS FOR FLT AT MY PLANNED ALT. AFTER CLBING TO ALT MY OAT READ 3 DEGS C, CONSISTENT WITH AN 11000' FREEZING LEVEL. AFTER ABOUT 10-15 MINS AT ALT I NOTICED THAT I WAS PICKING UP A SMALL AMOUNT OF MIXED ICE ON MY WINGS AND REQUESTED AND WAS GIVEN AN 8000' CRUISING ALT. SINCE THE OAT WAS ALREADY ABOVE THE FREEZING LEVEL I EXPECTED THAT A DSCNT OF 1000' WOULD BE MORE THAN ENOUGH TO CLEAR THE ICE. INSTEAD ICE BEGAN ACCUMULATING MORE RAPIDLY AS THE OAT REMAINED THE SAME AT THE LOWER ALT. AFTER ABOUT 5 MORE MINS I BEGAN ACCUMULATING SUFFICIENT ICE THAT I WAS NO LONGER ABLE TO MAINTAIN ALT. AT THIS POINT ICE WAS ACCUMULATING VERY RAPIDLY AND MY INDUCTION AIR BECAME BLOCKED AND MY ENG STARTED RUNNING ROUGH. STILL THE OAT READ 3 DEGS C. FINALLY WE BROKE OUT BTWN LAYERS AT ABOUT 7300' AND WITHIN A MINUTE OR TWO THE ICE BEGAN COMING OFF AND WE WERE ABLE TO CLB AGAIN TO 8000'. IN RETROSPECT I WISH I HAD ASKED THE ARCATA FSS FOR PIREPS BEFORE TKOF. IF I HAD HEARD PIREPS OF ICING I MIGHT HAVE CHOSEN A ROUTE WITH A LOWER MEA. ALTHOUGH I DIDN'T ASK, I WOULD HOPE THAT IN SUCH SITUATIONS FSS PERSONNEL WOULD VOLUNTEER SUCH PIREPS TO PLTS WHO ASK FOR THE FREEZING LEVEL. ONCE IN THE AIR I WISH I HAD TURNED BACK AT THE FIRST SIGN OF ICING. AT THAT POINT I COULD HAVE MADE IT BACK TO THE FOT VOR AND A LOWER MEA WITH NO DIFFICULTY. BY THE TIME I HAD DSNDED TO 8000' AND DETERMINED THAT THE ICE WAS STILL BUILDING UP, IT WAS A SHORTER DISTANCE TO TOMAD INTXN THAN BACK TO YAGER. BECAUSE OF THIS I DECIDED TO PROCEED TO TOMAD. THE ORIGINAL DECISION TO CONTINUE AT A LOWER ALT WAS FAULTY SINCE I DID NOT CONSIDER THE POSSIBILITY THAT ICE WOULD CONTINUE TO BUILD UP AT THAT LEVEL, LET ALONE THE POSSIBILITY THAT THE RATE OF BUILD UP COULD GET WORSE. FINALLY, NOTHING IN MY TRNING SUGGESTED TO ME THE POSSIBILITY THAT I COULD BUILD UP A SIGNIFICANT AMOUNT OF ICE WITH OUTSIDE TEMPS ABOVE FREEZING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: PLT INDICATES THAT A CHK ON THE STATIC OUTSIDE TEMP GAUGE REVEALED THAT IT WAS OFF BY 10 DEGS F. PIREPS WERE RPTED ENRTE BUT WERE FOR A HIGHER ALT THAN RPTR WAS UTILIZING. PLT DID GIVE A PIREP TO ZOA AFTER HE REGAINED LOST ALT. COUNSELING CONVERSATION BROUGHT OUT THE NEED FOR MORE DISCRETION TO BE EXHIBITED IN THE CHOICE OF ARWY AND HEIGHT OF UNDERLYING TERRAIN SO AS TO HAVE MORE LATITUDE IF A LOWER ALT IS REQUIRED. ALSO THE USE OF A 180 DEG TURN BEING A SMART AND EASY THING TO DO.

Data retrieved from NASA's ASRS site as of August 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.