Narrative:

I was on an IFR flight plan from hgr to cho. I was level at 6000 ft which was also the MEA along V143. I began to accumulate light rime ice. I saw dome clearing above and asked to climb to 8000 ft thinking I would be out of the clouds. Upon reaching 8000 ft I still remained IMC and continued to develop light ice (now about 1/2 inch). I asked to descend back to 6000 ft and was cleared to 6000 ft. During the descent my airspeed decreased to 0 KTS. I realized that I had forgotten to turn on the pitot heat allowing ice to cover the pitot tube. What I also forgot was that the static port on the small aircraft aircraft is also on the pitot tube. I turned on the pitot heat and continued to descend. I looked at the altimeter and it read 6600 ft so I continued to descend. The ice melted from the pitot tube and the altimeter spun rapidly down to 5700 ft, 300 ft below my assigned altitude and the MEA. I quickly added power and started to climb back to 6000 ft. At this time center called and asked my indicated altitude. I responded 5700 ft and correcting. Center made no further comments about my altitude. Within a few mins I was cleared to 5200 ft direct cho. The rest of the flight was uneventful. I will add the pitot heat to the checklist so I won't forget it next time I find myself in icing conditions. I will also be more attentive to the freezing level which was around 6000 ft, same as the MEA. As a CFI I plan to educate my students with this story, hopefully preventing future flts like this that might not end so well.

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Original NASA ASRS Text

Title: ENRTE WX VERY UNFRIENDLY TO SMA PLT WHEN HE FORGETS TO TURN ON HIS PITOT TUBE HEATER IN ICING CONDITIONS. ALTDEV LATER OCCURS.

Narrative: I WAS ON AN IFR FLT PLAN FROM HGR TO CHO. I WAS LEVEL AT 6000 FT WHICH WAS ALSO THE MEA ALONG V143. I BEGAN TO ACCUMULATE LIGHT RIME ICE. I SAW DOME CLRING ABOVE AND ASKED TO CLB TO 8000 FT THINKING I WOULD BE OUT OF THE CLOUDS. UPON REACHING 8000 FT I STILL REMAINED IMC AND CONTINUED TO DEVELOP LIGHT ICE (NOW ABOUT 1/2 INCH). I ASKED TO DSND BACK TO 6000 FT AND WAS CLRED TO 6000 FT. DURING THE DSCNT MY AIRSPD DECREASED TO 0 KTS. I REALIZED THAT I HAD FORGOTTEN TO TURN ON THE PITOT HEAT ALLOWING ICE TO COVER THE PITOT TUBE. WHAT I ALSO FORGOT WAS THAT THE STATIC PORT ON THE SMA ACFT IS ALSO ON THE PITOT TUBE. I TURNED ON THE PITOT HEAT AND CONTINUED TO DSND. I LOOKED AT THE ALTIMETER AND IT READ 6600 FT SO I CONTINUED TO DSND. THE ICE MELTED FROM THE PITOT TUBE AND THE ALTIMETER SPUN RAPIDLY DOWN TO 5700 FT, 300 FT BELOW MY ASSIGNED ALT AND THE MEA. I QUICKLY ADDED PWR AND STARTED TO CLB BACK TO 6000 FT. AT THIS TIME CTR CALLED AND ASKED MY INDICATED ALT. I RESPONDED 5700 FT AND CORRECTING. CTR MADE NO FURTHER COMMENTS ABOUT MY ALT. WITHIN A FEW MINS I WAS CLRED TO 5200 FT DIRECT CHO. THE REST OF THE FLT WAS UNEVENTFUL. I WILL ADD THE PITOT HEAT TO THE CHKLIST SO I WON'T FORGET IT NEXT TIME I FIND MYSELF IN ICING CONDITIONS. I WILL ALSO BE MORE ATTENTIVE TO THE FREEZING LEVEL WHICH WAS AROUND 6000 FT, SAME AS THE MEA. AS A CFI I PLAN TO EDUCATE MY STUDENTS WITH THIS STORY, HOPEFULLY PREVENTING FUTURE FLTS LIKE THIS THAT MIGHT NOT END SO WELL.

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.