Narrative:

On a feb/xa/99 IFR flight from myr to chs, I violated assigned altitude inadvertently. Departure from myr was routine and was IMC at 1200 ft and then on top at 4500 ft. As forecast, I was flying into improving conditions and chs was already good VFR. I could see 20-30 mi and as forecast, the overcast was breaking up to scattered to clear. I was given a descent from 6000 ft to what I heard to be 2000 ft by ATC. I repeated the descent clearance and reset my altitude hold bug to 2000 ft. About 20 DME from chs I noticed that I was flying at about the same ht as the 3 radio towers on mt pleasant (I fly this route regularly), and about the same time ATC called to advise me I was assigned 3000 ft and not the 2000 ft I was maintaining. Conclusion: I do not know whether the ATC tapes show me cleared to 2000 ft or 3000 ft, but the error was that I mentally transitioned to VFR while still on an IFR flight plan. Had I kept my mind in the cockpit and not watching the coast and distracted by the moderate turbulence, I would have noted my descent clearance violated the 2400 ft MEA on the IFR airway and called ATC for clarification prior to descent. Lesson: fly your IFR flight plan until you can and go VFR. Never mix or confuse the operations of the two! Altitude incursion while on IFR flight plan, due to lack of careful consideration of maintaining IFR rules when WX goes to cavu. Upon discovery by ATC, advised to maintain descent altitude and maintain obstacle clearance. ATC did not request a climb back to 3000 ft.

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Original NASA ASRS Text

Title: A PA32 PLT DSNDS 1000 FT BELOW HIS ASSIGNED ALT WHILE APCHING CHS, SC.

Narrative: ON A FEB/XA/99 IFR FLT FROM MYR TO CHS, I VIOLATED ASSIGNED ALT INADVERTENTLY. DEP FROM MYR WAS ROUTINE AND WAS IMC AT 1200 FT AND THEN ON TOP AT 4500 FT. AS FORECAST, I WAS FLYING INTO IMPROVING CONDITIONS AND CHS WAS ALREADY GOOD VFR. I COULD SEE 20-30 MI AND AS FORECAST, THE OVCST WAS BREAKING UP TO SCATTERED TO CLR. I WAS GIVEN A DSCNT FROM 6000 FT TO WHAT I HEARD TO BE 2000 FT BY ATC. I REPEATED THE DSCNT CLRNC AND RESET MY ALT HOLD BUG TO 2000 FT. ABOUT 20 DME FROM CHS I NOTICED THAT I WAS FLYING AT ABOUT THE SAME HT AS THE 3 RADIO TWRS ON MT PLEASANT (I FLY THIS RTE REGULARLY), AND ABOUT THE SAME TIME ATC CALLED TO ADVISE ME I WAS ASSIGNED 3000 FT AND NOT THE 2000 FT I WAS MAINTAINING. CONCLUSION: I DO NOT KNOW WHETHER THE ATC TAPES SHOW ME CLRED TO 2000 FT OR 3000 FT, BUT THE ERROR WAS THAT I MENTALLY TRANSITIONED TO VFR WHILE STILL ON AN IFR FLT PLAN. HAD I KEPT MY MIND IN THE COCKPIT AND NOT WATCHING THE COAST AND DISTRACTED BY THE MODERATE TURB, I WOULD HAVE NOTED MY DSCNT CLRNC VIOLATED THE 2400 FT MEA ON THE IFR AIRWAY AND CALLED ATC FOR CLARIFICATION PRIOR TO DSCNT. LESSON: FLY YOUR IFR FLT PLAN UNTIL YOU CAN AND GO VFR. NEVER MIX OR CONFUSE THE OPS OF THE TWO! ALT INCURSION WHILE ON IFR FLT PLAN, DUE TO LACK OF CAREFUL CONSIDERATION OF MAINTAINING IFR RULES WHEN WX GOES TO CAVU. UPON DISCOVERY BY ATC, ADVISED TO MAINTAIN DSCNT ALT AND MAINTAIN OBSTACLE CLRNC. ATC DID NOT REQUEST A CLB BACK TO 3000 FT.

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.