Narrative:

Flying at FL280, en route from ind to msy, we received a TCASII alert. TCASII alert consisted of a traffic call followed by a descend call. Captain started evasive action by disconnecting the autoplt and beginning a descent. ATC was notified of the RA. As the descent was initiated the first officer gained visual contact with the other aircraft. Aircraft was off our right side approximately 600 ft above and then it descended through our altitude. Once visual contact was gained altitude deviation stopped, total deviation consisted of 100 ft below assigned. Traffic was reported to ATC, but ATC said no traffic was in the area. ATC asked if we wanted to file a UFO report. Captain told ATC that it was definitely an aircraft, at which time ATC asked the captain about filing an near midair collision report.

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Original NASA ASRS Text

Title: A B727-200 CREW IN CRUISE, RESPONDED TO A DSND RA FROM TCASII.

Narrative: FLYING AT FL280, ENRTE FROM IND TO MSY, WE RECEIVED A TCASII ALERT. TCASII ALERT CONSISTED OF A TFC CALL FOLLOWED BY A DSND CALL. CAPT STARTED EVASIVE ACTION BY DISCONNECTING THE AUTOPLT AND BEGINNING A DSCNT. ATC WAS NOTIFIED OF THE RA. AS THE DSCNT WAS INITIATED THE FO GAINED VISUAL CONTACT WITH THE OTHER ACFT. ACFT WAS OFF OUR R SIDE APPROX 600 FT ABOVE AND THEN IT DSNDED THROUGH OUR ALT. ONCE VISUAL CONTACT WAS GAINED ALTDEV STOPPED, TOTAL DEV CONSISTED OF 100 FT BELOW ASSIGNED. TFC WAS RPTED TO ATC, BUT ATC SAID NO TFC WAS IN THE AREA. ATC ASKED IF WE WANTED TO FILE A UFO RPT. CAPT TOLD ATC THAT IT WAS DEFINITELY AN ACFT, AT WHICH TIME ATC ASKED THE CAPT ABOUT FILING AN NMAC RPT.

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.