Narrative:

I departed hio on a departure procedure that had an initial altitude assigned of 5000 ft. After being handed over to departure, I entered IMC (rain, ice and light turbulence) at about 3400 ft. I had engaged the altitude pre-select function on my flight director which should command a leveloff at the 5000 ft altitude which I set into the altitude alerter. I heard the altitude alerted 'ding' passing through 4000 ft (1000 ft to go), climbing at about 1800 FPM. At this point I noticed ice starting to build. I looked up to the overhead panel to turn on the anti-ice system (ignition overrides on, inlet heats on -- one at a time, propeller heat on, windshield heats on) and just as I finished setting all this up ATC called and asked me to verify level at 5000 ft. I looked at the altimeter and saw I was climbing through about 5500 ft, still at 1500 FPM! I disabled the autoplt and returned to altitude before re-engaging altitude preselect and autoplt but that took longer than I expected as I was in solid IMC with ice building, light turbulence and the negative G's associated with a pitch change from +1500 FPM to -1000 FPM were very disconcerting and I was on the edge of vertigo. Finally, after returning to 5000 ft, ATC called back and assigned me further climb. Somehow the altitude preselect mode had failed or not been engaged. As a further complication, the panel lights were in 'dim' and that made it very hard to verify that the mode was engaged. Further, in this airplane, one button 'toggles' the ps mode on or off, so it's not a simple matter to engage it without looking at the indicator light, as a push might disengage it rather than engage it. I think the lesson is to remain focused on leveloff and flying the airplane during that critical '1000 ft to go,' even if it meant holding off on the anti-ice for another 60 seconds.

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Original NASA ASRS Text

Title: A SINGLE PLT EXCEEDS ASSIGNED ALT BY 500 FT.

Narrative: I DEPARTED HIO ON A DEP PROC THAT HAD AN INITIAL ALT ASSIGNED OF 5000 FT. AFTER BEING HANDED OVER TO DEP, I ENTERED IMC (RAIN, ICE AND LIGHT TURB) AT ABOUT 3400 FT. I HAD ENGAGED THE ALT PRE-SELECT FUNCTION ON MY FLT DIRECTOR WHICH SHOULD COMMAND A LEVELOFF AT THE 5000 FT ALT WHICH I SET INTO THE ALT ALERTER. I HEARD THE ALT ALERTED 'DING' PASSING THROUGH 4000 FT (1000 FT TO GO), CLBING AT ABOUT 1800 FPM. AT THIS POINT I NOTICED ICE STARTING TO BUILD. I LOOKED UP TO THE OVERHEAD PANEL TO TURN ON THE ANTI-ICE SYS (IGNITION OVERRIDES ON, INLET HEATS ON -- ONE AT A TIME, PROP HEAT ON, WINDSHIELD HEATS ON) AND JUST AS I FINISHED SETTING ALL THIS UP ATC CALLED AND ASKED ME TO VERIFY LEVEL AT 5000 FT. I LOOKED AT THE ALTIMETER AND SAW I WAS CLBING THROUGH ABOUT 5500 FT, STILL AT 1500 FPM! I DISABLED THE AUTOPLT AND RETURNED TO ALT BEFORE RE-ENGAGING ALT PRESELECT AND AUTOPLT BUT THAT TOOK LONGER THAN I EXPECTED AS I WAS IN SOLID IMC WITH ICE BUILDING, LIGHT TURB AND THE NEGATIVE G'S ASSOCIATED WITH A PITCH CHANGE FROM +1500 FPM TO -1000 FPM WERE VERY DISCONCERTING AND I WAS ON THE EDGE OF VERTIGO. FINALLY, AFTER RETURNING TO 5000 FT, ATC CALLED BACK AND ASSIGNED ME FURTHER CLB. SOMEHOW THE ALT PRESELECT MODE HAD FAILED OR NOT BEEN ENGAGED. AS A FURTHER COMPLICATION, THE PANEL LIGHTS WERE IN 'DIM' AND THAT MADE IT VERY HARD TO VERIFY THAT THE MODE WAS ENGAGED. FURTHER, IN THIS AIRPLANE, ONE BUTTON 'TOGGLES' THE PS MODE ON OR OFF, SO IT'S NOT A SIMPLE MATTER TO ENGAGE IT WITHOUT LOOKING AT THE INDICATOR LIGHT, AS A PUSH MIGHT DISENGAGE IT RATHER THAN ENGAGE IT. I THINK THE LESSON IS TO REMAIN FOCUSED ON LEVELOFF AND FLYING THE AIRPLANE DURING THAT CRITICAL '1000 FT TO GO,' EVEN IF IT MEANT HOLDING OFF ON THE ANTI-ICE FOR ANOTHER 60 SECONDS.

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.