Narrative:

During the flight; I deviated from my altitude 3 times for 3 different reasons. It was a bad day and I'm sure fatigue played a role. The first altitude deviation was when I accidentally bumped the autoplt button without me knowing. I did not catch it until several mins later when I was about 200 ft from my assigned altitude. The second altitude deviation was on purpose. I was picking up moderate ice and my deice equipment was not keeping up. I had a request into center but he was busy on another frequency. So I made the choice to climb while I still had the chance. In my opinion it was the right choice. The airplane had so much ice I could only make about a 50 FPM climb. About 5 mins later; at 14200 ft; ATC asked my altitude. I told them 14200 ft and I needed 16000 ft for moderate ice. He said that he had traffic at 15000 ft and to stand by. About 5 mins later; he gave me the ok to climb from 14200 ft. I should have waited for approval to climb. The last altitude deviation was on approach to destination. Approach had me descend down to 5700 ft and for some reason I put 5500 ft in the altitude window. I caught myself descending below the assigned altitude on the base leg. The contributing factors were fatigue and the lack of experience in heavy icing conditions. I have learned my lesson to make sure that I'm well rested before accepting a trip and to be more assertive with ATC to get what I need when it comes to the safety of the aircraft. Callback conversation with reporter revealed the following information: the pilot stated that he did not at the time of the icing encounter consider declaring an emergency while attempting to climb above icing without a clearance. He ultimately received climb clearance when clear of traffic and prior to the point he considered his airframe icing to be critical. Fatigue was the major issue for him on this trip.

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Original NASA ASRS Text

Title: A C402 FREIGHT PLT HAD 3 ALTDEVS ON THE SAME TRIP: ICING DIVERSION; ACCIDENTAL AUTOPLT DISCONNECT; AND ALT ALERT MISSETTING.

Narrative: DURING THE FLT; I DEVIATED FROM MY ALT 3 TIMES FOR 3 DIFFERENT REASONS. IT WAS A BAD DAY AND I'M SURE FATIGUE PLAYED A ROLE. THE FIRST ALTDEV WAS WHEN I ACCIDENTALLY BUMPED THE AUTOPLT BUTTON WITHOUT ME KNOWING. I DID NOT CATCH IT UNTIL SEVERAL MINS LATER WHEN I WAS ABOUT 200 FT FROM MY ASSIGNED ALT. THE SECOND ALTDEV WAS ON PURPOSE. I WAS PICKING UP MODERATE ICE AND MY DEICE EQUIP WAS NOT KEEPING UP. I HAD A REQUEST INTO CTR BUT HE WAS BUSY ON ANOTHER FREQ. SO I MADE THE CHOICE TO CLB WHILE I STILL HAD THE CHANCE. IN MY OPINION IT WAS THE RIGHT CHOICE. THE AIRPLANE HAD SO MUCH ICE I COULD ONLY MAKE ABOUT A 50 FPM CLB. ABOUT 5 MINS LATER; AT 14200 FT; ATC ASKED MY ALT. I TOLD THEM 14200 FT AND I NEEDED 16000 FT FOR MODERATE ICE. HE SAID THAT HE HAD TFC AT 15000 FT AND TO STAND BY. ABOUT 5 MINS LATER; HE GAVE ME THE OK TO CLB FROM 14200 FT. I SHOULD HAVE WAITED FOR APPROVAL TO CLB. THE LAST ALTDEV WAS ON APCH TO DEST. APCH HAD ME DSND DOWN TO 5700 FT AND FOR SOME REASON I PUT 5500 FT IN THE ALT WINDOW. I CAUGHT MYSELF DSNDING BELOW THE ASSIGNED ALT ON THE BASE LEG. THE CONTRIBUTING FACTORS WERE FATIGUE AND THE LACK OF EXPERIENCE IN HVY ICING CONDITIONS. I HAVE LEARNED MY LESSON TO MAKE SURE THAT I'M WELL RESTED BEFORE ACCEPTING A TRIP AND TO BE MORE ASSERTIVE WITH ATC TO GET WHAT I NEED WHEN IT COMES TO THE SAFETY OF THE ACFT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE PLT STATED THAT HE DID NOT AT THE TIME OF THE ICING ENCOUNTER CONSIDER DECLARING AN EMER WHILE ATTEMPTING TO CLB ABOVE ICING WITHOUT A CLRNC. HE ULTIMATELY RECEIVED CLB CLRNC WHEN CLR OF TFC AND PRIOR TO THE POINT HE CONSIDERED HIS AIRFRAME ICING TO BE CRITICAL. FATIGUE WAS THE MAJOR ISSUE FOR HIM ON THIS TRIP.

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.