Narrative:

Our flight was operating on a regularly scheduled trip from lemd to ebbr. WX was no factor at altitude. We had begun our letdown just north of paris stepping down to FL180. The controller had been the last controller prior to the event reminded us to maintain FL180 as we approached that altitude. We leveled off and were proceeding via the STAR route into ebbr. Several mins later we received a clearance to descend to FL110. Since the french controllers typically speak both french and english it is very difficult to get an understanding of their traffic flow and/or what altitudes any aircraft are flying at. Her transmission to us was weak but discernible so I made a point of slowly and clearly reading it back to her. Our flight was call sign XXXX. After the readback I listened to hear any challenge on the controller's part as well as any other aircraft reading back a similar clearance which would alert me to the fact that something was amiss. The controller did not challenge my readback and no other aircraft on our frequency responded. After a brief pause the controller issued instructions to 3 other aircraft in normal fashion. She did not appear to be rushed. As we descended through FL167 she very excitedly told us to climb to and maintain FL180 and said it several times. The copilot immediately initiated an emergency climb to FL180. As we passed approximately FL174 we all observed the BE146 at our 11 O'clock and 2 mi. It passed well to our right. After all was done the controller asked why we descended. I told her because you told us to and we read it back to you. She testily told us to call brussels control and good bye. Causal factors: 2 languages, difficult speech patterns and sounds, not having the pictures on traffic on our or adjacent airways. Had I known of any traffic at FL170 I might have caught this error before it happened.

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Original NASA ASRS Text

Title: FLC FOREIGN CTLR MISCOM. LANGUAGE BARRIER AND CTLR FAILURE TO RESPOND TO RPTR'S READBACK OF DSCNT CLRNC. CTLR INTERVENED WHEN SEEING RPTR ACFT DSNDING INTO OTHER TFC.

Narrative: OUR FLT WAS OPERATING ON A REGULARLY SCHEDULED TRIP FROM LEMD TO EBBR. WX WAS NO FACTOR AT ALT. WE HAD BEGUN OUR LETDOWN JUST N OF PARIS STEPPING DOWN TO FL180. THE CTLR HAD BEEN THE LAST CTLR PRIOR TO THE EVENT REMINDED US TO MAINTAIN FL180 AS WE APCHED THAT ALT. WE LEVELED OFF AND WERE PROCEEDING VIA THE STAR RTE INTO EBBR. SEVERAL MINS LATER WE RECEIVED A CLRNC TO DSND TO FL110. SINCE THE FRENCH CTLRS TYPICALLY SPEAK BOTH FRENCH AND ENGLISH IT IS VERY DIFFICULT TO GET AN UNDERSTANDING OF THEIR TFC FLOW AND/OR WHAT ALTS ANY ACFT ARE FLYING AT. HER XMISSION TO US WAS WEAK BUT DISCERNIBLE SO I MADE A POINT OF SLOWLY AND CLRLY READING IT BACK TO HER. OUR FLT WAS CALL SIGN XXXX. AFTER THE READBACK I LISTENED TO HEAR ANY CHALLENGE ON THE CTLR'S PART AS WELL AS ANY OTHER ACFT READING BACK A SIMILAR CLRNC WHICH WOULD ALERT ME TO THE FACT THAT SOMETHING WAS AMISS. THE CTLR DID NOT CHALLENGE MY READBACK AND NO OTHER ACFT ON OUR FREQ RESPONDED. AFTER A BRIEF PAUSE THE CTLR ISSUED INSTRUCTIONS TO 3 OTHER ACFT IN NORMAL FASHION. SHE DID NOT APPEAR TO BE RUSHED. AS WE DSNDED THROUGH FL167 SHE VERY EXCITEDLY TOLD US TO CLB TO AND MAINTAIN FL180 AND SAID IT SEVERAL TIMES. THE COPLT IMMEDIATELY INITIATED AN EMER CLB TO FL180. AS WE PASSED APPROX FL174 WE ALL OBSERVED THE BE146 AT OUR 11 O'CLOCK AND 2 MI. IT PASSED WELL TO OUR R. AFTER ALL WAS DONE THE CTLR ASKED WHY WE DSNDED. I TOLD HER BECAUSE YOU TOLD US TO AND WE READ IT BACK TO YOU. SHE TESTILY TOLD US TO CALL BRUSSELS CTL AND GOOD BYE. CAUSAL FACTORS: 2 LANGUAGES, DIFFICULT SPEECH PATTERNS AND SOUNDS, NOT HAVING THE PICTURES ON TFC ON OUR OR ADJACENT AIRWAYS. HAD I KNOWN OF ANY TFC AT FL170 I MIGHT HAVE CAUGHT THIS ERROR BEFORE IT HAPPENED.

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.