Narrative:

Both pilots perceived the approach clearance 'expect visual 27L' and verbally repeated 'visual 27L.' the flight was given an intercept heading and altitude of 2500 ft MSL and told to call the airport in sight. The crew called the airport in sight at which time approach gave a clearance to 27R. However, the clearance was misunderstood and repeated back as clearance for the visual to 27L. Approach apparently corrected the runway to 27R. However, this clearance was not heard by either pilot and was not acknowledged. The pilot observed traffic 1000 ft above followed immediately by a TCASII RA to descend and approach directions to come right and join 27R. I feel that at a time when the crew was concentrating on maintaining a visual with 27L that the clearance was changed to the parallel runway. The breakdown occurred in the verbal acknowledgement of the newly assigned runway.

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Original NASA ASRS Text

Title: APCH TO WRONG RWY WHEN RADIO COM PROBLEM SIMULTANEOUS TRANSMISSION BLOCKS AMENDED APCH CLRNC.

Narrative: BOTH PLTS PERCEIVED THE APCH CLRNC 'EXPECT VISUAL 27L' AND VERBALLY REPEATED 'VISUAL 27L.' THE FLT WAS GIVEN AN INTERCEPT HDG AND ALT OF 2500 FT MSL AND TOLD TO CALL THE ARPT IN SIGHT. THE CREW CALLED THE ARPT IN SIGHT AT WHICH TIME APCH GAVE A CLRNC TO 27R. HOWEVER, THE CLRNC WAS MISUNDERSTOOD AND REPEATED BACK AS CLRNC FOR THE VISUAL TO 27L. APCH APPARENTLY CORRECTED THE RWY TO 27R. HOWEVER, THIS CLRNC WAS NOT HEARD BY EITHER PLT AND WAS NOT ACKNOWLEDGED. THE PLT OBSERVED TFC 1000 FT ABOVE FOLLOWED IMMEDIATELY BY A TCASII RA TO DSND AND APCH DIRECTIONS TO COME R AND JOIN 27R. I FEEL THAT AT A TIME WHEN THE CREW WAS CONCENTRATING ON MAINTAINING A VISUAL WITH 27L THAT THE CLRNC WAS CHANGED TO THE PARALLEL RWY. THE BREAKDOWN OCCURRED IN THE VERBAL ACKNOWLEDGEMENT OF THE NEWLY ASSIGNED RWY.

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.