Narrative:

Approach was extremely busy having just come out of a hold because of traffic saturation. Was being vectored for the 31L approach. Was vectored through the localizer and then through the 31R localizer (we were at 3000 ft). Was following a foreign carrier widebody transport. Approach asked if we could intercept the 31R localizer. Answered in the affirmative but was not told to intercept. Controller then gave instructions to a commuter to switch to the left runway. About the time we crossed the 31R localizer we received an RA with a descend command. Company policy is to leave the TCASII in TA/RA mode until 2000 ft and the requirement to respond to all commands unless doing so would further decrease safety. Descent was begun and an intercept of the localizer was also initiated after getting an all clear advisory. In reporting to approach what we had done they confirmed that they wanted us to do the intercept of the 31R localizer and that the RA had been caused by the commuter switching runways, keeping his speed up and crossing behind us with us in sight to expedite traffic flow. This is the second time in the last 6 months that the identical situation has occurred during approach. The other occurrence was at bna with an aircraft crossing behind us at higher speed going to the parallel runway. TCASII is great but it can be a pain when the aircraft is converging from the rear and has you in sight for a visual approach. We need mirrors in the large transport.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR LGT PIC RPTS ON TCASII RA FROM SAME DIRECTION TFC FROM THE REAR SETTING OFF TCASII RA. ALTDEV ALT EXCURSION.

Narrative: APCH WAS EXTREMELY BUSY HAVING JUST COME OUT OF A HOLD BECAUSE OF TFC SATURATION. WAS BEING VECTORED FOR THE 31L APCH. WAS VECTORED THROUGH THE LOC AND THEN THROUGH THE 31R LOC (WE WERE AT 3000 FT). WAS FOLLOWING A FOREIGN CARRIER WDB. APCH ASKED IF WE COULD INTERCEPT THE 31R LOC. ANSWERED IN THE AFFIRMATIVE BUT WAS NOT TOLD TO INTERCEPT. CTLR THEN GAVE INSTRUCTIONS TO A COMMUTER TO SWITCH TO THE L RWY. ABOUT THE TIME WE CROSSED THE 31R LOC WE RECEIVED AN RA WITH A DSND COMMAND. COMPANY POLICY IS TO LEAVE THE TCASII IN TA/RA MODE UNTIL 2000 FT AND THE REQUIREMENT TO RESPOND TO ALL COMMANDS UNLESS DOING SO WOULD FURTHER DECREASE SAFETY. DSCNT WAS BEGUN AND AN INTERCEPT OF THE LOC WAS ALSO INITIATED AFTER GETTING AN ALL CLR ADVISORY. IN RPTING TO APCH WHAT WE HAD DONE THEY CONFIRMED THAT THEY WANTED US TO DO THE INTERCEPT OF THE 31R LOC AND THAT THE RA HAD BEEN CAUSED BY THE COMMUTER SWITCHING RWYS, KEEPING HIS SPD UP AND XING BEHIND US WITH US IN SIGHT TO EXPEDITE TFC FLOW. THIS IS THE SECOND TIME IN THE LAST 6 MONTHS THAT THE IDENTICAL SIT HAS OCCURRED DURING APCH. THE OTHER OCCURRENCE WAS AT BNA WITH AN ACFT XING BEHIND US AT HIGHER SPD GOING TO THE PARALLEL RWY. TCASII IS GREAT BUT IT CAN BE A PAIN WHEN THE ACFT IS CONVERGING FROM THE REAR AND HAS YOU IN SIGHT FOR A VISUAL APCH. WE NEED MIRRORS IN THE LGT.

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.