Narrative:

While in cruise at FL370 en route to bwi; we received a TA followed almost immediately by an RA commanding a descent in excess of 2000 FPM. I immediately disengaged the autoplt and followed the HUD RA guidance; xchking the vsi; which showed the 2000+ FPM descent requirement. My first officer notified ZJX that we were descending due to an RA. We heard another company aircraft (flight number unknown) that was passing over us opposite direction at FL380 also indicate that they had received an RA. After descending about 1000 ft; the RA quit and we climbed back to FL370. My first officer monitored the TCAS display during the event and said the other aircraft showed +500 ft directly over the top of us at the closest point. Prior to the RA; we had been in light to moderate chop at FL370. While we were experiencing fairly large mach excursions (.74 - .81 mach); I was monitoring our altitude and the autoplt appeared to be doing a good job of maintaining altitude (+/-40 ft). My initial impression during the event was that the aircraft flying over us at FL380 had inadvertently deviated from their altitude due to the turbulent flight conditions and caused the RA. However; when we queried ZJX after the event; the controller indicated that the other flight had been cleared to descend from FL380 to FL320. I later spoke with a supervisor at ZJX to try to find out if this was an rvsm issue or controller error. The supervisor advised me that she had already completed an investigation of the event; and the event was due to controller error (there were significant route deviations occurring due to WX in the area and the controller had apparently forgotten about us when he cleared the other company aircraft to descend through our altitude; he was pulled from duty following the event). She indicated that the quick response to the RA by both aircraft had prevented an operational error. If there was ever a situation that proved the worth of TCAS; this was it. Without trying to be overly dramatic; both my first officer and I believe that; but for that RA; 2 company jets probably would have collided at FL370 that night.

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Original NASA ASRS Text

Title: B737 WITH ZJX AT FL370 EXPERIENCED TCAS RA WITH OPPOSITE DIRECTION TFC AS CTLR ERRED IN DSCNT CLRNC ISSUANCE; RA ACTION(S) SAVED SEPARATION.

Narrative: WHILE IN CRUISE AT FL370 ENRTE TO BWI; WE RECEIVED A TA FOLLOWED ALMOST IMMEDIATELY BY AN RA COMMANDING A DSCNT IN EXCESS OF 2000 FPM. I IMMEDIATELY DISENGAGED THE AUTOPLT AND FOLLOWED THE HUD RA GUIDANCE; XCHKING THE VSI; WHICH SHOWED THE 2000+ FPM DSCNT REQUIREMENT. MY FO NOTIFIED ZJX THAT WE WERE DSNDING DUE TO AN RA. WE HEARD ANOTHER COMPANY ACFT (FLT NUMBER UNKNOWN) THAT WAS PASSING OVER US OPPOSITE DIRECTION AT FL380 ALSO INDICATE THAT THEY HAD RECEIVED AN RA. AFTER DSNDING ABOUT 1000 FT; THE RA QUIT AND WE CLBED BACK TO FL370. MY FO MONITORED THE TCAS DISPLAY DURING THE EVENT AND SAID THE OTHER ACFT SHOWED +500 FT DIRECTLY OVER THE TOP OF US AT THE CLOSEST POINT. PRIOR TO THE RA; WE HAD BEEN IN LIGHT TO MODERATE CHOP AT FL370. WHILE WE WERE EXPERIENCING FAIRLY LARGE MACH EXCURSIONS (.74 - .81 MACH); I WAS MONITORING OUR ALT AND THE AUTOPLT APPEARED TO BE DOING A GOOD JOB OF MAINTAINING ALT (+/-40 FT). MY INITIAL IMPRESSION DURING THE EVENT WAS THAT THE ACFT FLYING OVER US AT FL380 HAD INADVERTENTLY DEVIATED FROM THEIR ALT DUE TO THE TURBULENT FLT CONDITIONS AND CAUSED THE RA. HOWEVER; WHEN WE QUERIED ZJX AFTER THE EVENT; THE CTLR INDICATED THAT THE OTHER FLT HAD BEEN CLRED TO DSND FROM FL380 TO FL320. I LATER SPOKE WITH A SUPVR AT ZJX TO TRY TO FIND OUT IF THIS WAS AN RVSM ISSUE OR CTLR ERROR. THE SUPVR ADVISED ME THAT SHE HAD ALREADY COMPLETED AN INVESTIGATION OF THE EVENT; AND THE EVENT WAS DUE TO CTLR ERROR (THERE WERE SIGNIFICANT RTE DEVS OCCURRING DUE TO WX IN THE AREA AND THE CTLR HAD APPARENTLY FORGOTTEN ABOUT US WHEN HE CLRED THE OTHER COMPANY ACFT TO DSND THROUGH OUR ALT; HE WAS PULLED FROM DUTY FOLLOWING THE EVENT). SHE INDICATED THAT THE QUICK RESPONSE TO THE RA BY BOTH ACFT HAD PREVENTED AN OPERROR. IF THERE WAS EVER A SITUATION THAT PROVED THE WORTH OF TCAS; THIS WAS IT. WITHOUT TRYING TO BE OVERLY DRAMATIC; BOTH MY FO AND I BELIEVE THAT; BUT FOR THAT RA; 2 COMPANY JETS PROBABLY WOULD HAVE COLLIDED AT FL370 THAT NIGHT.

Data retrieved from NASA's ASRS site as of January 2009 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.