Narrative:

While at level cruise, on autoplt, at FL330 on J51 inbound to sav, at approximately XX27Z, we experienced a 'descend, descend' aural warning along with red 'descend' messages on both primary flight displays. I reacted immediately by disengaging the autoplt and pushed over. At that very moment, the aural 'descend' warning changed to an aural 'traffic, traffic' advisory with amber 'traffic' messages displayed on both primary flight displays. ATC 'called' and we spotted opposite direction traffic at FL310. I leveled the aircraft immediately losing less than 300 ft and started a climb back to FL330. I reported the RA to ATC. The controller was unaware of any possible conflict. My trip terminated at rdo. On return home, I rehashed the event and went over the system. I then became aware that the RA 'descend' commands were without guidance commands. Coming to the conclusion that the 'descend warning' was possibly spurious and potentially dangerous, I called our maintenance control duty officer and passed on the information and my concerns to him. He agreed to have maintenance at rdo do a system check.

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Original NASA ASRS Text

Title: CAPT OF A CANADAIR REGIONAL JET, CL65, DSNDED IN RESPONSE TO A TCASII RA RESULTING IN A CONFLICT WITH ANOTHER ACFT IN LEVEL FLT 2000 FT BELOW. FLC SUSPECTS THAT THE TCASII HAD GIVEN A FALSE WARNING SINCE ARTCC CTLR ADVISED OF NO KNOWN CONFLICTING TFC.

Narrative: WHILE AT LEVEL CRUISE, ON AUTOPLT, AT FL330 ON J51 INBOUND TO SAV, AT APPROX XX27Z, WE EXPERIENCED A 'DSND, DSND' AURAL WARNING ALONG WITH RED 'DSND' MESSAGES ON BOTH PRIMARY FLT DISPLAYS. I REACTED IMMEDIATELY BY DISENGAGING THE AUTOPLT AND PUSHED OVER. AT THAT VERY MOMENT, THE AURAL 'DSND' WARNING CHANGED TO AN AURAL 'TFC, TFC' ADVISORY WITH AMBER 'TFC' MESSAGES DISPLAYED ON BOTH PRIMARY FLT DISPLAYS. ATC 'CALLED' AND WE SPOTTED OPPOSITE DIRECTION TFC AT FL310. I LEVELED THE ACFT IMMEDIATELY LOSING LESS THAN 300 FT AND STARTED A CLB BACK TO FL330. I RPTED THE RA TO ATC. THE CTLR WAS UNAWARE OF ANY POSSIBLE CONFLICT. MY TRIP TERMINATED AT RDO. ON RETURN HOME, I REHASHED THE EVENT AND WENT OVER THE SYS. I THEN BECAME AWARE THAT THE RA 'DSND' COMMANDS WERE WITHOUT GUIDANCE COMMANDS. COMING TO THE CONCLUSION THAT THE 'DSND WARNING' WAS POSSIBLY SPURIOUS AND POTENTIALLY DANGEROUS, I CALLED OUR MAINT CTL DUTY OFFICER AND PASSED ON THE INFO AND MY CONCERNS TO HIM. HE AGREED TO HAVE MAINT AT RDO DO A SYS CHK.

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.