Narrative:

I was flying south from bellingham in an small aircraft to practice a holding pattern at the ritts NDB, followed by an NDB and ILS approach. I initially was issued a standard holding pattern at 5000'. The hold was in the clouds and the plane was beginning to pick up rime ice. When I noticed the ice forming I requested from ZSE, sector 3 to descend because of icing. I was issued a clearance to descend to 4000' and continue holding. After I descended to 4000' ice still appeared to be on the plane and it reacted sluggishly to control wheel inputs. I became very concerned about how much the ice could affect the plane if it accumulated any more and requested from ZSE to begin the NDB approach. Center told me to continue holding because a plane was coming outbnd from paine field to the ritz NDB for the ILS approach, which is on the same line as the inbound leg of the NDB hold. The other plane was at 3000' MSL. The incident occurred when I was completing my turn to the inbound leg. The airspeed dropped from approximately 130 KTS to 80 KTS, so I reacted by lowering the nose of the plane and increasing throttle (manifold pressure). Airspeed increased back to around 130 KTS, but I had lost 800' and broken out of the clouds. The other plane was in sight at the 2 O'clock position on my windshield. The controller asked my altitude and requested an immediate climb. In retrospect I should have declared an emergency, but my main concern was flying the plane. On 1/thurs/90,I had an instrument shop on boeing field examine the static-pitot system, and they found a broken part in the pitot tube which could cause false readings. Apparently it caused a bad reading on the night of 1/wed/90.

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Original NASA ASRS Text

Title: ALT DEVIATION.

Narrative: I WAS FLYING S FROM BELLINGHAM IN AN SMA TO PRACTICE A HOLDING PATTERN AT THE RITTS NDB, FOLLOWED BY AN NDB AND ILS APCH. I INITIALLY WAS ISSUED A STANDARD HOLDING PATTERN AT 5000'. THE HOLD WAS IN THE CLOUDS AND THE PLANE WAS BEGINNING TO PICK UP RIME ICE. WHEN I NOTICED THE ICE FORMING I REQUESTED FROM ZSE, SECTOR 3 TO DSND BECAUSE OF ICING. I WAS ISSUED A CLRNC TO DSND TO 4000' AND CONTINUE HOLDING. AFTER I DSNDED TO 4000' ICE STILL APPEARED TO BE ON THE PLANE AND IT REACTED SLUGGISHLY TO CONTROL WHEEL INPUTS. I BECAME VERY CONCERNED ABOUT HOW MUCH THE ICE COULD AFFECT THE PLANE IF IT ACCUMULATED ANY MORE AND REQUESTED FROM ZSE TO BEGIN THE NDB APCH. CENTER TOLD ME TO CONTINUE HOLDING BECAUSE A PLANE WAS COMING OUTBND FROM PAINE FIELD TO THE RITZ NDB FOR THE ILS APCH, WHICH IS ON THE SAME LINE AS THE INBND LEG OF THE NDB HOLD. THE OTHER PLANE WAS AT 3000' MSL. THE INCIDENT OCCURRED WHEN I WAS COMPLETING MY TURN TO THE INBND LEG. THE AIRSPD DROPPED FROM APPROX 130 KTS TO 80 KTS, SO I REACTED BY LOWERING THE NOSE OF THE PLANE AND INCREASING THROTTLE (MANIFOLD PRESSURE). AIRSPD INCREASED BACK TO AROUND 130 KTS, BUT I HAD LOST 800' AND BROKEN OUT OF THE CLOUDS. THE OTHER PLANE WAS IN SIGHT AT THE 2 O'CLOCK POS ON MY WINDSHIELD. THE CTLR ASKED MY ALT AND REQUESTED AN IMMEDIATE CLB. IN RETROSPECT I SHOULD HAVE DECLARED AN EMER, BUT MY MAIN CONCERN WAS FLYING THE PLANE. ON 1/THURS/90,I HAD AN INSTRUMENT SHOP ON BOEING FIELD EXAMINE THE STATIC-PITOT SYS, AND THEY FOUND A BROKEN PART IN THE PITOT TUBE WHICH COULD CAUSE FALSE READINGS. APPARENTLY IT CAUSED A BAD READING ON THE NIGHT OF 1/WED/90.

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.