Narrative:

After taking off from ofk, I turned eastbound at about 2000 ft AGL, I began to experience ice. In this area, ZMP approach can only hear me above 4000 ft MSL (3000 ft AGL). I was operating on a void time clearance, and I was to 'check-in' with ZMP (at 4000 ft). Also, my company informed me that I was to fly to a different destination (other than flight planned). As soon as I reached 4000 ft MSL, I tried to contact minneapolis, they were very busy. I was in a big hurry to climb because of the ice and I was also trying to tell them that I needed to change my destination. While checking on with center I also asked for 6000 ft MSL, although I didn't say why, I should have said why. The controller asked me to verify requesting 6000 ft. At this point, I was just below 5000 ft MSL and still picking up ice through all of the anxiety of the ice and the need to change my destination, I didn't realize that the controller did not clear me to 6000 ft MSL. At about 5600 ft MSL, the controller asked me to verify 5000 ft. I responded by saying, 'negative, climbing through 5600 ft for 6000 ft.' controller responded, 'I cleared you to 5000 ft, you're now cleared to 6000 ft.' nothing further about the incident was said. What I feel happened was that the anxiety of ice (icing conditions) contributed to me not hearing exactly what the controller said) and/or thinking he actually cleared me to 6000 ft MSL. If I was put in the same situation again, I would tell the controller that I was in icing conditions and that I needed higher. Also, I will use an idea that a fellow pilot told me the following night -- use the ADF card as a makeshift altitude assignment reminder.

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Original NASA ASRS Text

Title: PART 135 ATX PLT DEPARTED CLRED ALT WITHOUT PROPER CLRNC IN ICING CONDITIONS FROM OFK, NE.

Narrative: AFTER TAKING OFF FROM OFK, I TURNED EBOUND AT ABOUT 2000 FT AGL, I BEGAN TO EXPERIENCE ICE. IN THIS AREA, ZMP APCH CAN ONLY HEAR ME ABOVE 4000 FT MSL (3000 FT AGL). I WAS OPERATING ON A VOID TIME CLRNC, AND I WAS TO 'CHK-IN' WITH ZMP (AT 4000 FT). ALSO, MY COMPANY INFORMED ME THAT I WAS TO FLY TO A DIFFERENT DEST (OTHER THAN FLT PLANNED). AS SOON AS I REACHED 4000 FT MSL, I TRIED TO CONTACT MINNEAPOLIS, THEY WERE VERY BUSY. I WAS IN A BIG HURRY TO CLB BECAUSE OF THE ICE AND I WAS ALSO TRYING TO TELL THEM THAT I NEEDED TO CHANGE MY DEST. WHILE CHKING ON WITH CTR I ALSO ASKED FOR 6000 FT MSL, ALTHOUGH I DIDN'T SAY WHY, I SHOULD HAVE SAID WHY. THE CTLR ASKED ME TO VERIFY REQUESTING 6000 FT. AT THIS POINT, I WAS JUST BELOW 5000 FT MSL AND STILL PICKING UP ICE THROUGH ALL OF THE ANXIETY OF THE ICE AND THE NEED TO CHANGE MY DEST, I DIDN'T REALIZE THAT THE CTLR DID NOT CLR ME TO 6000 FT MSL. AT ABOUT 5600 FT MSL, THE CTLR ASKED ME TO VERIFY 5000 FT. I RESPONDED BY SAYING, 'NEGATIVE, CLBING THROUGH 5600 FT FOR 6000 FT.' CTLR RESPONDED, 'I CLRED YOU TO 5000 FT, YOU'RE NOW CLRED TO 6000 FT.' NOTHING FURTHER ABOUT THE INCIDENT WAS SAID. WHAT I FEEL HAPPENED WAS THAT THE ANXIETY OF ICE (ICING CONDITIONS) CONTRIBUTED TO ME NOT HEARING EXACTLY WHAT THE CTLR SAID) AND/OR THINKING HE ACTUALLY CLRED ME TO 6000 FT MSL. IF I WAS PUT IN THE SAME SIT AGAIN, I WOULD TELL THE CTLR THAT I WAS IN ICING CONDITIONS AND THAT I NEEDED HIGHER. ALSO, I WILL USE AN IDEA THAT A FELLOW PLT TOLD ME THE FOLLOWING NIGHT -- USE THE ADF CARD AS A MAKESHIFT ALT ASSIGNMENT REMINDER.

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.