Narrative:

Air carrier X was established on J541, westbound between yak and jnu at FL200. Air carrier Y departed yak eastbound to jnu via 7541, climbing to FL190, reference air carrier X. At XA34Z air carrier X reported 42.8 DME east of yak. I then asked air carrier Y his DME east of yak, and I heard '44 DME east.' I climbed air carrier Y to FL290. The pilot did not question this clearance, but I later learned that air carrier Y had reported '34 DME east of yak.' the pilot of air carrier Y stopped his climb at FL190 until he had visibility passage with air carrier X which he reported at XA35Z. At that time, I questioned the pilots one the DME's they had given, and that's when air carrier Y said he had reported '34 DME' instead of '44.' I then reported to the area supervisor that a possible operational error had occurred. The tapes were pulled and indicated that air carrier Y had indeed reported '34 DME east of yak.' I think that a readback on my part and/or correct phraseology reference # usage on the pilot's part would have prevented the situation. Supplemental information from acn 144235: we had just leveled at FL190 with an expected climb to FL290. We had previously monitored a call from air carrier X at FL200, reporting over forat intersection (65 DME east yak), with an estimate for yak. We were initially climbing to FL190 eastbound toward forat. We discussed when we would pass air carrier X (my first officer and I) and at 30 DME east of yak we called air carrier X on ATC frequency and asked their DME from yak (we were at 30 DME east). Air carrier X responded, '42.8.' shortly thereafter zan asked us what our DME was. We checked and told them '34 DME.' they subsequently cleared us to maintain FL290. After a brief discussion in the cockpit, we decided to delay our climb out of FL290 until we had visibility passage. Very shortly thereafter we made visibility contact with air carrier X passing overhead, and then continued our climb to FL290 west/O further incident. I feel that either the controller had our DME's reversed in his mind or misunderstood our DME report. A few mins later ATC called and asked what DME we had reported earlier. We said, '34 DME,' and they said the controller heard '40.' had we made an immediate climb when cleared, a possible accident could have occurred.

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Original NASA ASRS Text

Title: CTLR MISHEARD DME DISTANCE FROM ACR PLT AND ISSUED A CLIMB THROUGH AN OCCUPIED ALT. ACR PLT DELAYED CLIMB UNTIL AFTER CONFLICTING TRAFFIC PASSED.

Narrative: ACR X WAS ESTABLISHED ON J541, WBND BTWN YAK AND JNU AT FL200. ACR Y DEPARTED YAK EBND TO JNU VIA 7541, CLBING TO FL190, REF ACR X. AT XA34Z ACR X RPTED 42.8 DME E OF YAK. I THEN ASKED ACR Y HIS DME E OF YAK, AND I HEARD '44 DME E.' I CLBED ACR Y TO FL290. THE PLT DID NOT QUESTION THIS CLRNC, BUT I LATER LEARNED THAT ACR Y HAD RPTED '34 DME E OF YAK.' THE PLT OF ACR Y STOPPED HIS CLB AT FL190 UNTIL HE HAD VIS PASSAGE WITH ACR X WHICH HE RPTED AT XA35Z. AT THAT TIME, I QUESTIONED THE PLTS ONE THE DME'S THEY HAD GIVEN, AND THAT'S WHEN ACR Y SAID HE HAD RPTED '34 DME' INSTEAD OF '44.' I THEN RPTED TO THE AREA SUPVR THAT A POSSIBLE OPERROR HAD OCCURRED. THE TAPES WERE PULLED AND INDICATED THAT ACR Y HAD INDEED RPTED '34 DME E OF YAK.' I THINK THAT A READBACK ON MY PART AND/OR CORRECT PHRASEOLOGY REF # USAGE ON THE PLT'S PART WOULD HAVE PREVENTED THE SITUATION. SUPPLEMENTAL INFO FROM ACN 144235: WE HAD JUST LEVELED AT FL190 WITH AN EXPECTED CLB TO FL290. WE HAD PREVIOUSLY MONITORED A CALL FROM ACR X AT FL200, RPTING OVER FORAT INTXN (65 DME E YAK), WITH AN ESTIMATE FOR YAK. WE WERE INITIALLY CLBING TO FL190 EBND TOWARD FORAT. WE DISCUSSED WHEN WE WOULD PASS ACR X (MY F/O AND I) AND AT 30 DME E OF YAK WE CALLED ACR X ON ATC FREQ AND ASKED THEIR DME FROM YAK (WE WERE AT 30 DME E). ACR X RESPONDED, '42.8.' SHORTLY THEREAFTER ZAN ASKED US WHAT OUR DME WAS. WE CHKED AND TOLD THEM '34 DME.' THEY SUBSEQUENTLY CLRED US TO MAINTAIN FL290. AFTER A BRIEF DISCUSSION IN THE COCKPIT, WE DECIDED TO DELAY OUR CLB OUT OF FL290 UNTIL WE HAD VIS PASSAGE. VERY SHORTLY THEREAFTER WE MADE VIS CONTACT WITH ACR X PASSING OVERHEAD, AND THEN CONTINUED OUR CLB TO FL290 W/O FURTHER INCIDENT. I FEEL THAT EITHER THE CTLR HAD OUR DME'S REVERSED IN HIS MIND OR MISUNDERSTOOD OUR DME RPT. A FEW MINS LATER ATC CALLED AND ASKED WHAT DME WE HAD RPTED EARLIER. WE SAID, '34 DME,' AND THEY SAID THE CTLR HEARD '40.' HAD WE MADE AN IMMEDIATE CLB WHEN CLRED, A POSSIBLE ACCIDENT COULD HAVE OCCURRED.

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.