BE20 pilot overshoots altitude on descent into spi after misinterping descent clearance.

Attributes
ACN	428010
Time
Date	199902
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : spi.airport
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 9000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : spi.tracon
Operator	general aviation : corporate
Make Model Name	Super King Air 200/Huron
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 50 flight time total : 16000 flight time type : 11000
ASRS Report	428010
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Cleared from 10000 ft to 9000 ft. Thought it was 5000 ft.

Original NASA ASRS Text

Title: BE20 PLT OVERSHOOTS ALT ON DSCNT INTO SPI AFTER MISINTERPING DSCNT CLRNC.

Narrative: CLRED FROM 10000 FT TO 9000 FT. THOUGHT IT WAS 5000 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.