A B737 first officer reported a misunderstanding of an altitude change clearance from ZJX.

Attributes
ACN	479640
Time
Date	200007
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sav.airport
State Reference	GA
Altitude	msl bound lower : 10000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx.artcc tracon : sav.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Route In Use	departure sid : n/s
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 230 flight time total : 7500 flight time type : 7000
ASRS Report	479640
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot non adherence : published procedure non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Ambiguous

Narrative:

On climb out from sav to clt, departure control cleared us to 12000 ft. Autoplt was on, so I put 12000 ft in the MCP altitude window and read back '12000 ft.' both PF and PNF verified 12000 ft. When we checked in with ZJX at about 9500 ft, ATC asked us if we were climbing to 10000 ft. Told him we were cleared to 12000 ft as we were passing through +/-10500. He said he thought we were cleared to 10000 ft, cleared us to 11000 ft, then said he would check with departure control. That was the last we heard about the clearance limit of 10000 ft versus 12000 ft from ATC.

Original NASA ASRS Text

Title: A B737 FO RPTED A MISUNDERSTANDING OF AN ALT CHANGE CLRNC FROM ZJX.

Narrative: ON CLBOUT FROM SAV TO CLT, DEP CTL CLRED US TO 12000 FT. AUTOPLT WAS ON, SO I PUT 12000 FT IN THE MCP ALT WINDOW AND READ BACK '12000 FT.' BOTH PF AND PNF VERIFIED 12000 FT. WHEN WE CHKED IN WITH ZJX AT ABOUT 9500 FT, ATC ASKED US IF WE WERE CLBING TO 10000 FT. TOLD HIM WE WERE CLRED TO 12000 FT AS WE WERE PASSING THROUGH +/-10500. HE SAID HE THOUGHT WE WERE CLRED TO 10000 FT, CLRED US TO 11000 FT, THEN SAID HE WOULD CHK WITH DEP CTL. THAT WAS THE LAST WE HEARD ABOUT THE CLRNC LIMIT OF 10000 FT VERSUS 12000 FT FROM ATC.

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.