Air carrier had assigned altitude questioned by ATC.

Attributes
ACN	296900
Time
Date	199502
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : rjtg
State Reference	FO
Altitude	msl bound lower : 31000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : rjtg tower : atl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 20000 flight time type : 1200
ASRS Report	296900
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Clearance to maintain FL330 was amended to maintain FL310. We reported FL310 at ukata and vasko. By vasko, requested FL370. ATC requested confirmation that we were at FL310 not at FL330. We neither received a subsequent clearance to FL330 nor did we read back such a clearance. After receiving clearance to FL370, we climbed to and maintained FL370.

Original NASA ASRS Text

Title: ACR HAD ASSIGNED ALT QUESTIONED BY ATC.

Narrative: CLRNC TO MAINTAIN FL330 WAS AMENDED TO MAINTAIN FL310. WE RPTED FL310 AT UKATA AND VASKO. BY VASKO, REQUESTED FL370. ATC REQUESTED CONFIRMATION THAT WE WERE AT FL310 NOT AT FL330. WE NEITHER RECEIVED A SUBSEQUENT CLRNC TO FL330 NOR DID WE READ BACK SUCH A CLRNC. AFTER RECEIVING CLRNC TO FL370, WE CLBED TO AND MAINTAINED FL370.

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.