An F100 air carrier pilot reported a hearback readback problem with ZAU regarding assigned altitude.

Attributes
ACN	511110
Time
Date	200105
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zau.artcc
State Reference	IL
Altitude	msl bound lower : 22000 msl bound upper : 22500
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	511110
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Resolutory Action	controller : issued advisory
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

Were given and read back a climb to FL230. Passing FL225, were told we were supposed to level at FL220. Immediately descended to FL220. No traffic conflicts existed and nothing else was said by the controller.

Original NASA ASRS Text

Title: AN F100 ACR PLT RPTED A HEARBACK READBACK PROB WITH ZAU REGARDING ASSIGNED ALT.

Narrative: WERE GIVEN AND READ BACK A CLB TO FL230. PASSING FL225, WERE TOLD WE WERE SUPPOSED TO LEVEL AT FL220. IMMEDIATELY DSNDED TO FL220. NO TFC CONFLICTS EXISTED AND NOTHING ELSE WAS SAID BY THE CTLR.

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.