B777-200 crew was given a climb the controller later questioned.

Attributes
ACN	516380
Time
Date	200106
Day	Fri
Local Time Of Day	0001 To 0600
Place
Locale Reference	atc facility : lfrr.artcc
State Reference	FO
Altitude	msl bound lower : 37000 msl bound upper : 39000
Environment
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B777 Undifferentiated or Other Model
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	516380
Events
Resolutory Action	controller : issued alert controller : issued new clearance flight crew : returned to assigned altitude
Consequence	other
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Altitude deviation. Captain PF, ZZZ-zrh. Upon returning to the cockpit from my rest break, first officer and relief pilot informed me of an altitude misunderstanding with brest control. On initial contact at FL370, both felt they were told to climb to FL390 and given a slight route change. First officer acknowledged the climb to FL390, asked for a clarification of the route change, and they commenced the climb to FL390. Controller clarified the route, but as they were climbing through approximately FL380, he questioned whether they were maintaining FL370. First officer replied no, that they were cleared to FL390. The controller stated they were not and to return to FL370, which they immediately did. There was no apparent traffic conflict and the nearest aircraft they observed was 8 NM ahead at FL390, traveling in the same direction. As previously stated, both the first officer and relief pilot felt they heard a clearance to climb to FL390.

Original NASA ASRS Text

Title: B777-200 CREW WAS GIVEN A CLB THE CTLR LATER QUESTIONED.

Narrative: ALTDEV. CAPT PF, ZZZ-ZRH. UPON RETURNING TO THE COCKPIT FROM MY REST BREAK, FO AND RELIEF PLT INFORMED ME OF AN ALT MISUNDERSTANDING WITH BREST CTL. ON INITIAL CONTACT AT FL370, BOTH FELT THEY WERE TOLD TO CLB TO FL390 AND GIVEN A SLIGHT RTE CHANGE. FO ACKNOWLEDGED THE CLB TO FL390, ASKED FOR A CLARIFICATION OF THE RTE CHANGE, AND THEY COMMENCED THE CLB TO FL390. CTLR CLARIFIED THE RTE, BUT AS THEY WERE CLBING THROUGH APPROX FL380, HE QUESTIONED WHETHER THEY WERE MAINTAINING FL370. FO REPLIED NO, THAT THEY WERE CLRED TO FL390. THE CTLR STATED THEY WERE NOT AND TO RETURN TO FL370, WHICH THEY IMMEDIATELY DID. THERE WAS NO APPARENT TFC CONFLICT AND THE NEAREST ACFT THEY OBSERVED WAS 8 NM AHEAD AT FL390, TRAVELING IN THE SAME DIRECTION. AS PREVIOUSLY STATED, BOTH THE FO AND RELIEF PLT FELT THEY HEARD A CLRNC TO CLB TO FL390.

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.