Narrative:

Aircraft was in cruise from rjaa to panc at FL410. Communications up to this point were conducted on VHF. With the handoff from VHF communications to our assigned HF frequency, the new controller requested we climb to FL430. (This was an earlier request by the previous controller on VHF but advised him we did not want to climb to FL430 due to warmer than forecast isa temperature thus we were cleared to cruise at FL410 with a further climb to FL430 at a fix 725 NM ahead, this was acceptable). We also advised the new controller of the warmer than forecast isa temperature and offered to descend (as low as FL310). Instead we were issued a clearance to cross pawes at FL420 or above, cleared to FL430. The climb was initiated meeting the crossing restriction and leveled at FL430. During cruise we noticed the sat fluctuating, and progressively increasing (isa +15C). Associated along with this was some light turbulence. Continued flight at this altitude would not be practical and requested a descent to FL410. Control said they were unable, we requested we needed the descent and wanted to begin our descent to FL410 now. We received the clearance to FL410. I feel that there was a misunderstanding in the communications between the VHF controller and the HF controller to the fact that our climb to FL430 was not to be initiated for another 700+ NM. To further confuse the issue, the controller did not seem to be aware of the effect on performance that the increased temperature had, and a descent was needed to operate the aircraft safely. A climb to the higher altitude later could be done due to the reduced weight from fuel burn. Also, HF communications are difficult due to poor reception, heavy accents and sometimes less than perfect english.

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Original NASA ASRS Text

Title: FLC OF CPR ADVTECH MLG EXPERIENCES LANGUAGE BARRIER DIFFICULTIES ON OVER-WATER FLT.

Narrative: ACFT WAS IN CRUISE FROM RJAA TO PANC AT FL410. COMS UP TO THIS POINT WERE CONDUCTED ON VHF. WITH THE HDOF FROM VHF COMS TO OUR ASSIGNED HF FREQ, THE NEW CTLR REQUESTED WE CLB TO FL430. (THIS WAS AN EARLIER REQUEST BY THE PREVIOUS CTLR ON VHF BUT ADVISED HIM WE DID NOT WANT TO CLB TO FL430 DUE TO WARMER THAN FORECAST ISA TEMP THUS WE WERE CLRED TO CRUISE AT FL410 WITH A FURTHER CLB TO FL430 AT A FIX 725 NM AHEAD, THIS WAS ACCEPTABLE). WE ALSO ADVISED THE NEW CTLR OF THE WARMER THAN FORECAST ISA TEMP AND OFFERED TO DSND (AS LOW AS FL310). INSTEAD WE WERE ISSUED A CLRNC TO CROSS PAWES AT FL420 OR ABOVE, CLRED TO FL430. THE CLB WAS INITIATED MEETING THE XING RESTRICTION AND LEVELED AT FL430. DURING CRUISE WE NOTICED THE SAT FLUCTUATING, AND PROGRESSIVELY INCREASING (ISA +15C). ASSOCIATED ALONG WITH THIS WAS SOME LIGHT TURB. CONTINUED FLT AT THIS ALT WOULD NOT BE PRACTICAL AND REQUESTED A DSCNT TO FL410. CTL SAID THEY WERE UNABLE, WE REQUESTED WE NEEDED THE DSCNT AND WANTED TO BEGIN OUR DSCNT TO FL410 NOW. WE RECEIVED THE CLRNC TO FL410. I FEEL THAT THERE WAS A MISUNDERSTANDING IN THE COMS BTWN THE VHF CTLR AND THE HF CTLR TO THE FACT THAT OUR CLB TO FL430 WAS NOT TO BE INITIATED FOR ANOTHER 700+ NM. TO FURTHER CONFUSE THE ISSUE, THE CTLR DID NOT SEEM TO BE AWARE OF THE EFFECT ON PERFORMANCE THAT THE INCREASED TEMP HAD, AND A DSCNT WAS NEEDED TO OPERATE THE ACFT SAFELY. A CLB TO THE HIGHER ALT LATER COULD BE DONE DUE TO THE REDUCED WT FROM FUEL BURN. ALSO, HF COMS ARE DIFFICULT DUE TO POOR RECEPTION, HVY ACCENTS AND SOMETIMES LESS THAN PERFECT ENGLISH.

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.