Narrative:

While repositioning aircraft to ZZZ and descending from 17000 ft MSL in IMC and moderate rime icing conditions; with all anti-icing equipment selected on; I experienced smoke in the cockpit while passing through approximately 10000 ft. When I changed frequencys to approach; as requested by center; but before checking in; I first smelled and then observed smoke coming from behind the instrument panel directly in front of me. I believe that I was cleared to descend to 9000 ft; although it may have been 7000 ft; but in all the ensuing confusion; trying to communicate my emergency to ATC; responding to their requests; hand fly the aircraft; while trying to determine and isolate the source of the problem; I may have descended through the altitude that I was previously cleared to descend to. As previously stated; I am unsure as to whether I was previously cleared to 9000 ft or 7000 ft. At around 7800 ft; I managed to stop the smoke by turning off the environmental control switch and the windshield heat. After collecting my wits; I queried ATC and asked them what altitude they wanted me at. They responded by authorizing me to descend to 4000 ft. They did not indicate that I had busted my altitude or violated my clearance in any way; but I believe that in all the confusion I may have; as I cannot remember whether I had been previously cleared to 9000 ft or 7000 ft. I continued to my destination and landed without incident; somewhat shaken but nevertheless relieved to be safely on the ground. I do not have any suggestions as to how to prevent this potential incident from recurring; but altitude preselect equipment would have been a nice addition to this aircraft. Thinking back; I seriously doubt that being asked for 'number of souls on board and fuel remaining' did anything to help me deal with the emergency; but rather only served to distract me from the task at hand and increased my concern about my predicament; should that be possible. Regardless; asking this information is redundant at best; as it is already on the flight plan. It certainly had no bearing on my situation and did nothing to help me resolve the problem. At best; it only served to contribute to the confusion and provided an unnecessary distraction. I believe that requiring this information; when indicated on flight plan; is a waste and adds confusion.

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Original NASA ASRS Text

Title: BE10 PLT DECLARES EMERGENCY WHEN COCKPIT FILLS WITH SMOKE. MAY HAVE FAILED TO LEVEL AT CLRED ALT.

Narrative: WHILE REPOSITIONING ACFT TO ZZZ AND DSNDING FROM 17000 FT MSL IN IMC AND MODERATE RIME ICING CONDITIONS; WITH ALL ANTI-ICING EQUIP SELECTED ON; I EXPERIENCED SMOKE IN THE COCKPIT WHILE PASSING THROUGH APPROX 10000 FT. WHEN I CHANGED FREQS TO APCH; AS REQUESTED BY CTR; BUT BEFORE CHKING IN; I FIRST SMELLED AND THEN OBSERVED SMOKE COMING FROM BEHIND THE INST PANEL DIRECTLY IN FRONT OF ME. I BELIEVE THAT I WAS CLRED TO DSND TO 9000 FT; ALTHOUGH IT MAY HAVE BEEN 7000 FT; BUT IN ALL THE ENSUING CONFUSION; TRYING TO COMMUNICATE MY EMER TO ATC; RESPONDING TO THEIR REQUESTS; HAND FLY THE ACFT; WHILE TRYING TO DETERMINE AND ISOLATE THE SOURCE OF THE PROB; I MAY HAVE DSNDED THROUGH THE ALT THAT I WAS PREVIOUSLY CLRED TO DSND TO. AS PREVIOUSLY STATED; I AM UNSURE AS TO WHETHER I WAS PREVIOUSLY CLRED TO 9000 FT OR 7000 FT. AT AROUND 7800 FT; I MANAGED TO STOP THE SMOKE BY TURNING OFF THE ENVIRONMENTAL CTL SWITCH AND THE WINDSHIELD HEAT. AFTER COLLECTING MY WITS; I QUERIED ATC AND ASKED THEM WHAT ALT THEY WANTED ME AT. THEY RESPONDED BY AUTHORIZING ME TO DSND TO 4000 FT. THEY DID NOT INDICATE THAT I HAD BUSTED MY ALT OR VIOLATED MY CLRNC IN ANY WAY; BUT I BELIEVE THAT IN ALL THE CONFUSION I MAY HAVE; AS I CANNOT REMEMBER WHETHER I HAD BEEN PREVIOUSLY CLRED TO 9000 FT OR 7000 FT. I CONTINUED TO MY DEST AND LANDED WITHOUT INCIDENT; SOMEWHAT SHAKEN BUT NEVERTHELESS RELIEVED TO BE SAFELY ON THE GND. I DO NOT HAVE ANY SUGGESTIONS AS TO HOW TO PREVENT THIS POTENTIAL INCIDENT FROM RECURRING; BUT ALT PRESELECT EQUIP WOULD HAVE BEEN A NICE ADDITION TO THIS ACFT. THINKING BACK; I SERIOUSLY DOUBT THAT BEING ASKED FOR 'NUMBER OF SOULS ON BOARD AND FUEL REMAINING' DID ANYTHING TO HELP ME DEAL WITH THE EMER; BUT RATHER ONLY SERVED TO DISTRACT ME FROM THE TASK AT HAND AND INCREASED MY CONCERN ABOUT MY PREDICAMENT; SHOULD THAT BE POSSIBLE. REGARDLESS; ASKING THIS INFO IS REDUNDANT AT BEST; AS IT IS ALREADY ON THE FLT PLAN. IT CERTAINLY HAD NO BEARING ON MY SITUATION AND DID NOTHING TO HELP ME RESOLVE THE PROB. AT BEST; IT ONLY SERVED TO CONTRIBUTE TO THE CONFUSION AND PROVIDED AN UNNECESSARY DISTR. I BELIEVE THAT REQUIRING THIS INFO; WHEN INDICATED ON FLT PLAN; IS A WASTE AND ADDS CONFUSION.

Data retrieved from NASA's ASRS site as of January 2009 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.