Narrative:

This flight originated on puerto plata and terminated in dallas ft worth. Our original route of flight took us through santo domingo control's airspace along A636 and into port of prince control over retak intersection. We were originally cleared by santo domingo to FL220. We arrived at retak intersection at FL220 and I gave a position report to port of prince control. They responded and told us to maintain 220. Their english was very broken and I understood them to say 'maintain 230'. I read it back as such and they replied 'say altitude'. I said 'out of 220 for 230'. They came back 'negative, descend now, maintain 220'. At this same time my first officer, who was flying that leg, also told me that he understood the controller to say FL220. He continued to fly at 220 and held that altitude. The reason for center's urgency became apparent as we spotted an air carrier large transport ahead of us on the airway at FL230 going the opposite direction. I confirmed to center that we were at FL220 and we passed almost directly beneath the air carrier flight. After we passed, the pilot of the air carrier Y flight came on the radio and said he had just had a near miss. At that time he sounded very agitated and upset. While the situation turned out well there was the potential for a very hazardous conflict. The situation drove several points home to me. First is the importance of listening very carefully to controller's instructions. Particularly in non radar environments and where the controllers speak marginal english. Also the importance of crew coordination and reading back clrncs came into play. Fortunately these both worked well in this situation allowing both the controller and my first officer to bring to my attention my misinterp before it became critical error. One thing I do feel would have added to the safety of the situation. It would have helped if we had been made aware of the position of the air carrier Y flight at an earlier time. This would have allowed us to be looking for the traffic earlier and we would have known in advance that 230 was an unreasonable altitude for us to be assigned at that time.

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Original NASA ASRS Text

Title: RADIO COM PROBLEM SPEECH RATE VOICE QUALITY CREATES A CLRNC INTERP PROBLEM FOR RPTR AS HE RPTS LEAVING AN ASSIGNED ALT.

Narrative: THIS FLT ORIGINATED ON PUERTO PLATA AND TERMINATED IN DALLAS FT WORTH. OUR ORIGINAL RTE OF FLT TOOK US THROUGH SANTO DOMINGO CTL'S AIRSPACE ALONG A636 AND INTO PORT OF PRINCE CTL OVER RETAK INTXN. WE WERE ORIGINALLY CLRED BY SANTO DOMINGO TO FL220. WE ARRIVED AT RETAK INTXN AT FL220 AND I GAVE A POS RPT TO PORT OF PRINCE CTL. THEY RESPONDED AND TOLD US TO MAINTAIN 220. THEIR ENGLISH WAS VERY BROKEN AND I UNDERSTOOD THEM TO SAY 'MAINTAIN 230'. I READ IT BACK AS SUCH AND THEY REPLIED 'SAY ALT'. I SAID 'OUT OF 220 FOR 230'. THEY CAME BACK 'NEGATIVE, DSND NOW, MAINTAIN 220'. AT THIS SAME TIME MY FO, WHO WAS FLYING THAT LEG, ALSO TOLD ME THAT HE UNDERSTOOD THE CTLR TO SAY FL220. HE CONTINUED TO FLY AT 220 AND HELD THAT ALT. THE REASON FOR CENTER'S URGENCY BECAME APPARENT AS WE SPOTTED AN ACR LGT AHEAD OF US ON THE AIRWAY AT FL230 GOING THE OPPOSITE DIRECTION. I CONFIRMED TO CENTER THAT WE WERE AT FL220 AND WE PASSED ALMOST DIRECTLY BENEATH THE ACR FLT. AFTER WE PASSED, THE PLT OF THE ACR Y FLT CAME ON THE RADIO AND SAID HE HAD JUST HAD A NEAR MISS. AT THAT TIME HE SOUNDED VERY AGITATED AND UPSET. WHILE THE SITUATION TURNED OUT WELL THERE WAS THE POTENTIAL FOR A VERY HAZARDOUS CONFLICT. THE SITUATION DROVE SEVERAL POINTS HOME TO ME. FIRST IS THE IMPORTANCE OF LISTENING VERY CAREFULLY TO CTLR'S INSTRUCTIONS. PARTICULARLY IN NON RADAR ENVIRONMENTS AND WHERE THE CTLRS SPEAK MARGINAL ENGLISH. ALSO THE IMPORTANCE OF CREW COORD AND READING BACK CLRNCS CAME INTO PLAY. FORTUNATELY THESE BOTH WORKED WELL IN THIS SITUATION ALLOWING BOTH THE CTLR AND MY FO TO BRING TO MY ATTN MY MISINTERP BEFORE IT BECAME CRITICAL ERROR. ONE THING I DO FEEL WOULD HAVE ADDED TO THE SAFETY OF THE SITUATION. IT WOULD HAVE HELPED IF WE HAD BEEN MADE AWARE OF THE POS OF THE ACR Y FLT AT AN EARLIER TIME. THIS WOULD HAVE ALLOWED US TO BE LOOKING FOR THE TFC EARLIER AND WE WOULD HAVE KNOWN IN ADVANCE THAT 230 WAS AN UNREASONABLE ALT FOR US TO BE ASSIGNED AT THAT TIME.

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.