Pilot of light twin descends below cleared to altitude after misinterping clearance.

Attributes
ACN	422250
Time
Date	199812
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : btr
State Reference	LA
Altitude	msl bound lower : 2000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air taxi
Flight Phase	descent other
Route In Use	arrival other enroute : direct
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : commercial
Experience	flight time last 90 days : 300 flight time total : 1455 flight time type : 250
ASRS Report	422250
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	altitude deviation : overshoot non adherence : far
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Air Traffic Incident	Operational Deviation Pilot Deviation

Narrative:

This situation occurred due to my failure to properly listen for the altitude clearance given. (I was cleared to descend to 3000 ft MSL and I descended to 2000 ft MSL.) to facilitate my error, a 'readback/hearback' error occurred where I read back my clearance with the incorrect altitude of 2000 ft MSL and the controller didn't catch my mistake. I believe the causes of my problem include a combination of preoccupation with descent planning and my lack of attention to the details of my clearance received. I feel that to prevent this situation from occurring again, I must have better discipline while communicating.

Original NASA ASRS Text

Title: PLT OF LIGHT TWIN DSNDS BELOW CLRED TO ALT AFTER MISINTERPING CLRNC.

Narrative: THIS SIT OCCURRED DUE TO MY FAILURE TO PROPERLY LISTEN FOR THE ALT CLRNC GIVEN. (I WAS CLRED TO DSND TO 3000 FT MSL AND I DSNDED TO 2000 FT MSL.) TO FACILITATE MY ERROR, A 'READBACK/HEARBACK' ERROR OCCURRED WHERE I READ BACK MY CLRNC WITH THE INCORRECT ALT OF 2000 FT MSL AND THE CTLR DIDN'T CATCH MY MISTAKE. I BELIEVE THE CAUSES OF MY PROB INCLUDE A COMBINATION OF PREOCCUPATION WITH DSCNT PLANNING AND MY LACK OF ATTN TO THE DETAILS OF MY CLRNC RECEIVED. I FEEL THAT TO PREVENT THIS SIT FROM OCCURRING AGAIN, I MUST HAVE BETTER DISCIPLINE WHILE COMMUNICATING.

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.