Narrative:

Air carrier X was on vectors to downwind at rdu leveling at 8000 ft. Traffic was issued 2 O'clock, 7 mi, an medium large transport air carrier Y leaving 5000 for 7000 wbound. Air carrier X reported traffic in sight. He was told the traffic would pass below him and continue climb off his left. He rogered the transmission. 1 min later air carrier X crew advised they were responding to TCASII RA and were climbing. He climbed to 8500 ft. I again told him air carrier Y was restr below him at 7000 ft. At this point no safety or danger occurred, but a very normal procedure at rdu is to climb departure to 7000, arrs stay at 8000 ft. If the same situation would have occurred 10 mins earlier where overflts at 9000, 9500, and 10000 were being worked, it could have been disastrous. Respond to TCASII when a crew feels it necessary for safety and the other aircraft is not in sight. With the numbers of aircraft flying today there is not always going to be room to climb or descend because of TCASII. TCASII equipment doesn't realize when aircraft are sighted visually. By the way, air carrier X was TCASII equipped and never got an RA.

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Original NASA ASRS Text

Title: ACR X UNAUTHORIZED CLB FROM ASSIGNED ALT. DUE TO TCASII RA. EVASIVE ACTION TAKEN. PLTDEV.

Narrative: ACR X WAS ON VECTORS TO DOWNWIND AT RDU LEVELING AT 8000 FT. TFC WAS ISSUED 2 O'CLOCK, 7 MI, AN MLG ACR Y LEAVING 5000 FOR 7000 WBOUND. ACR X RPTED TFC IN SIGHT. HE WAS TOLD THE TFC WOULD PASS BELOW HIM AND CONTINUE CLB OFF HIS L. HE ROGERED THE XMISSION. 1 MIN LATER ACR X CREW ADVISED THEY WERE RESPONDING TO TCASII RA AND WERE CLBING. HE CLBED TO 8500 FT. I AGAIN TOLD HIM ACR Y WAS RESTR BELOW HIM AT 7000 FT. AT THIS POINT NO SAFETY OR DANGER OCCURRED, BUT A VERY NORMAL PROC AT RDU IS TO CLB DEP TO 7000, ARRS STAY AT 8000 FT. IF THE SAME SITUATION WOULD HAVE OCCURRED 10 MINS EARLIER WHERE OVERFLTS AT 9000, 9500, AND 10000 WERE BEING WORKED, IT COULD HAVE BEEN DISASTROUS. RESPOND TO TCASII WHEN A CREW FEELS IT NECESSARY FOR SAFETY AND THE OTHER ACFT IS NOT IN SIGHT. WITH THE NUMBERS OF ACFT FLYING TODAY THERE IS NOT ALWAYS GOING TO BE ROOM TO CLB OR DSND BECAUSE OF TCASII. TCASII EQUIP DOESN'T REALIZE WHEN ACFT ARE SIGHTED VISUALLY. BY THE WAY, ACR X WAS TCASII EQUIPPED AND NEVER GOT AN RA.

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.