Narrative:

Was cleared for VOR DME 12 approach at cun. Told to maintain 3000' until 5 DME on outbnd leg. Cloud deck (ceiling), 3000'. Mindset/thought controller cleared us for visibility to maintain 3000' until 5 DME. At 5.5 DME saw airport and started turn toward airport (right turn). Was not told nor was aware of another aircraft in area. With wing up (right turn), approach path was blocked from view. We did not reconfirm clearance instructions--mexican's hard to understand. We should have flown out to 8 DME on outbnd leg, then turned as approach called for. Supplemental information from acn 149807: just as we rolled out on to the final approach course I observed an air carrier large transport Y approximately 500-1000' directly below us and faster than we were. I immediately advised the captain and he initiated a missed approach.

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Original NASA ASRS Text

Title: ACR MLG FLT CREW CONDUCTS UNAUTH APCH PROC AT CUN.

Narrative: WAS CLRED FOR VOR DME 12 APCH AT CUN. TOLD TO MAINTAIN 3000' UNTIL 5 DME ON OUTBND LEG. CLOUD DECK (CEILING), 3000'. MINDSET/THOUGHT CTLR CLRED US FOR VIS TO MAINTAIN 3000' UNTIL 5 DME. AT 5.5 DME SAW ARPT AND STARTED TURN TOWARD ARPT (RIGHT TURN). WAS NOT TOLD NOR WAS AWARE OF ANOTHER ACFT IN AREA. WITH WING UP (RIGHT TURN), APCH PATH WAS BLOCKED FROM VIEW. WE DID NOT RECONFIRM CLRNC INSTRUCTIONS--MEXICAN'S HARD TO UNDERSTAND. WE SHOULD HAVE FLOWN OUT TO 8 DME ON OUTBND LEG, THEN TURNED AS APCH CALLED FOR. SUPPLEMENTAL INFO FROM ACN 149807: JUST AS WE ROLLED OUT ON TO THE FINAL APCH COURSE I OBSERVED AN ACR LGT Y APPROX 500-1000' DIRECTLY BELOW US AND FASTER THAN WE WERE. I IMMEDIATELY ADVISED THE CAPT AND HE INITIATED A MISSED APCH.

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.