Narrative:

We had just canceled IFR 15 NM from destination airport in severe clear conditions. When the tcasi alarm went off, we both looked at the tcasi to see a target less than 5 mi at 12 O'clock and 400-600 ft below us. I looked outside then inside to change tcasi range from 20 NM to 5 NM. Again, we looked outside intently for several seconds. Captain spotted traffic at 12 O'clock and 12 mi and called 'there he is.' first officer, PF, said 'where' as the captain (myself) grabbed controls in an evasive right 35 degree bank. Had we not had tcasi we probably would have missed the traffic by a larger margin because we would not have stopped our descent to look for traffic. Tcasi is of model that does not provide evasive instruction for direction. Only provides alert to traffic. Other aircraft did not see us. Passenger mentioned how close aircraft was.

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Original NASA ASRS Text

Title: A BE02 FLC STOPPED THEIR DSCNT WHEN THEY RECEIVED A TCASI ALARM, AND THEN TOOK EVASIVE ACTION WHEN THEY DISCOVERED THAT A DH6 WAS CLOSE TO THEIR ALT. THE CAPT TOOK CTL OF THE ACFT AND RPTS THAT WITHOUT THE TCASI, THE ACFT WOULD HAVE PASSED AT A WIDER MARGIN SINCE THE FLC WOULD NOT HAVE STOPPED THEIR DSCNT.

Narrative: WE HAD JUST CANCELED IFR 15 NM FROM DEST ARPT IN SEVERE CLR CONDITIONS. WHEN THE TCASI ALARM WENT OFF, WE BOTH LOOKED AT THE TCASI TO SEE A TARGET LESS THAN 5 MI AT 12 O'CLOCK AND 400-600 FT BELOW US. I LOOKED OUTSIDE THEN INSIDE TO CHANGE TCASI RANGE FROM 20 NM TO 5 NM. AGAIN, WE LOOKED OUTSIDE INTENTLY FOR SEVERAL SECONDS. CAPT SPOTTED TFC AT 12 O'CLOCK AND 12 MI AND CALLED 'THERE HE IS.' FO, PF, SAID 'WHERE' AS THE CAPT (MYSELF) GRABBED CTLS IN AN EVASIVE R 35 DEG BANK. HAD WE NOT HAD TCASI WE PROBABLY WOULD HAVE MISSED THE TFC BY A LARGER MARGIN BECAUSE WE WOULD NOT HAVE STOPPED OUR DSCNT TO LOOK FOR TFC. TCASI IS OF MODEL THAT DOES NOT PROVIDE EVASIVE INSTRUCTION FOR DIRECTION. ONLY PROVIDES ALERT TO TFC. OTHER ACFT DID NOT SEE US. PAX MENTIONED HOW CLOSE ACFT WAS.

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.