Narrative:

While in cruise at FL280 I first noticed traffic indicated on TCASII at 1 O'clock position 800 ft above descending. Shortly thereafter received a TA and then a 'descend' RA. I commenced an 1800 FPM descent on the autoplt until we received the 'clear of conflict' at FL270, at which time we leveled off. We did not hear any calls from ATC to the traffic and ATC did not seem to be aware of the traffic. The closest I saw on the TCASII was 500 ft above, however, the captain saw 300 ft above. Among the concerns we discussed following this incident was a need for simulator training and a more standardized procedure for the crew to handle a RA. Overall though, the system worked and since we never acquired the traffic visually, I cannot say how close we really got but I feel TCASII in this incident may have saved a great many lives.

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Original NASA ASRS Text

Title: PLT REACTING TO TCASII ALERT DSNDS BELOW ASSIGNED ALT.

Narrative: WHILE IN CRUISE AT FL280 I FIRST NOTICED TFC INDICATED ON TCASII AT 1 O'CLOCK POS 800 FT ABOVE DSNDING. SHORTLY THEREAFTER RECEIVED A TA AND THEN A 'DSND' RA. I COMMENCED AN 1800 FPM DSCNT ON THE AUTOPLT UNTIL WE RECEIVED THE 'CLR OF CONFLICT' AT FL270, AT WHICH TIME WE LEVELED OFF. WE DID NOT HEAR ANY CALLS FROM ATC TO THE TFC AND ATC DID NOT SEEM TO BE AWARE OF THE TFC. THE CLOSEST I SAW ON THE TCASII WAS 500 FT ABOVE, HOWEVER, THE CAPT SAW 300 FT ABOVE. AMONG THE CONCERNS WE DISCUSSED FOLLOWING THIS INCIDENT WAS A NEED FOR SIMULATOR TRAINING AND A MORE STANDARDIZED PROC FOR THE CREW TO HANDLE A RA. OVERALL THOUGH, THE SYS WORKED AND SINCE WE NEVER ACQUIRED THE TFC VISUALLY, I CANNOT SAY HOW CLOSE WE REALLY GOT BUT I FEEL TCASII IN THIS INCIDENT MAY HAVE SAVED A GREAT MANY LIVES.

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.