A flight crew thought they were assigned to a different altitude than the center controller thought.

Attributes
ACN	518870
Time
Date	200107
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : cae.vortac
State Reference	SC
Altitude	msl bound lower : 23000 msl bound upper : 23700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 7500 flight time type : 400
ASRS Report	518870
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Resolutory Action	controller : issued new clearance flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

While climbing thru FL237 to assigned altitude of FL260 controller asked us to verify level at FL230. We acknowledged we were climbing thru FL237 and we were instructed to expedite back down to FL230 which we complied with. Both myself (captain) and my first officer understood our previous climb clearance to be FL260. No TCASII event took place and no traffic conflict is known to this crew.

Original NASA ASRS Text

Title: A FLT CREW THOUGHT THEY WERE ASSIGNED TO A DIFFERENT ALT THAN THE CTR CTLR THOUGHT.

Narrative: WHILE CLBING THRU FL237 TO ASSIGNED ALT OF FL260 CTLR ASKED US TO VERIFY LEVEL AT FL230. WE ACKNOWLEDGED WE WERE CLBING THRU FL237 AND WE WERE INSTRUCTED TO EXPEDITE BACK DOWN TO FL230 WHICH WE COMPLIED WITH. BOTH MYSELF (CAPT) AND MY FO UNDERSTOOD OUR PREVIOUS CLB CLRNC TO BE FL260. NO TCASII EVENT TOOK PLACE AND NO TFC CONFLICT IS KNOWN TO THIS CREW.

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.