Narrative:

While cruising at 6000', in an IFR flight plan from 3s2 to 1s0, I was given a vector and altitude change (descent). After the controller asked me to verify that my destination was 1s0, which I did, he gave me a vector direct and said, 'you can descend to 5000'.' I've flown this route many times and at this time I was expecting a descent clearance to 3000', as I've gotten many times before. (The MEA is 5000', but I believe the MVA is 3000'.) for some reason I just read back the heading and not the altitude. Anyway, I promptly descended to 3000' (at 2000+ FPM). At 5000' I entered IMC in the overcast and broke out at about 3200'. The first thing I noticed was my close proximity to the ground (about 1000'). The second thing I noticed is that I wasn't as far north as I thought I was; I had just passed over the ridge of hills that makes the MEA 5000'. In a couple of mins I was away from the hills and about 2000' AGL. After about 2 mins the controller came back and told me I was only cleared to 5000' and asked if had terrain clearance. I replied in the affirmative, and as I was now in VMC and close to home, I cancelled IFR. I don't know why I didn't read back my altitude clearance--I'm usually very good at that. You can certainly bet I'll be even better in the future, and, I'll also listen closer to the clrncs.

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Original NASA ASRS Text

Title: GA SMA ALT DEV OVERSHOT DURING DESCENT. ACFT WAS IFR AND CLEARED TO 5000', BUT CONTINUED DESCENT TO 3000'. MEA IS 5000'.

Narrative: WHILE CRUISING AT 6000', IN AN IFR FLT PLAN FROM 3S2 TO 1S0, I WAS GIVEN A VECTOR AND ALT CHANGE (DSCNT). AFTER THE CTLR ASKED ME TO VERIFY THAT MY DEST WAS 1S0, WHICH I DID, HE GAVE ME A VECTOR DIRECT AND SAID, 'YOU CAN DSND TO 5000'.' I'VE FLOWN THIS ROUTE MANY TIMES AND AT THIS TIME I WAS EXPECTING A DSCNT CLRNC TO 3000', AS I'VE GOTTEN MANY TIMES BEFORE. (THE MEA IS 5000', BUT I BELIEVE THE MVA IS 3000'.) FOR SOME REASON I JUST READ BACK THE HDG AND NOT THE ALT. ANYWAY, I PROMPTLY DSNDED TO 3000' (AT 2000+ FPM). AT 5000' I ENTERED IMC IN THE OVCST AND BROKE OUT AT ABOUT 3200'. THE FIRST THING I NOTICED WAS MY CLOSE PROX TO THE GND (ABOUT 1000'). THE SECOND THING I NOTICED IS THAT I WASN'T AS FAR N AS I THOUGHT I WAS; I HAD JUST PASSED OVER THE RIDGE OF HILLS THAT MAKES THE MEA 5000'. IN A COUPLE OF MINS I WAS AWAY FROM THE HILLS AND ABOUT 2000' AGL. AFTER ABOUT 2 MINS THE CTLR CAME BACK AND TOLD ME I WAS ONLY CLRED TO 5000' AND ASKED IF HAD TERRAIN CLRNC. I REPLIED IN THE AFFIRMATIVE, AND AS I WAS NOW IN VMC AND CLOSE TO HOME, I CANCELLED IFR. I DON'T KNOW WHY I DIDN'T READ BACK MY ALT CLRNC--I'M USUALLY VERY GOOD AT THAT. YOU CAN CERTAINLY BET I'LL BE EVEN BETTER IN THE FUTURE, AND, I'LL ALSO LISTEN CLOSER TO THE CLRNCS.

Data retrieved from NASA's ASRS site as of August 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.