Narrative:

A large WX system covered central fl involving moderate turbulence and moderate icing. All aircraft in the area had to deviate to the east to circumvent WX while simultaneously seeking lower altitudes for smoother rides. The controller was extremely busy issuing turns, dscnts and frequency changes almost constantly. It was difficult to transmit without stepping on him. We were deviating east to an opening in the line of WX after having descended from FL330 (moderate turbulence) to FL230 (light to moderate turbulence). As we reached the opening (20- 30 mi deviation as approved by ATC), controller directed a turn to 340 degrees, soon after which there was a controller change. The new controller directed us to do a 180 degree turn toward pie. Just as we reached the new heading sbound at FL230, aircraft directly in front of us at FL210 heading toward us began an ATC directed climb. This aircraft was not reported on our ATC frequency. TCASII immediately displayed an RA with the aural alert 'climb, climb.' the fly-to arc was red everywhere except for a small green arc from approximately 3500 FPM to 4000 FPM. We began a climb while trying to burn through constant chatter to declare emergency. In the climb we squawked 7700 and continued to attempt calls to ATC. RA remained until reaching FL250 at which time ATC asked if our emergency was over and directed us back down to FL230. (The other aircraft had leveled off at FL220.) we had turned slightly (approximately 30 degrees) in the climb so we also resumed our heading as directed towards pie. We eventually cleared the WX and further descent to 11000 ft resulted in leaving turbulence at approximately FL200. We arrived in rsw without further incident. Conclusion: due to WX, turbulence and number of aircraft, ATC became overloaded, so much so that some aircraft reversed course and returned to their point of origin. RA might have been aggravated by other aircraft's aggressive climb to FL220. Perhaps he was getting a poor ride at FL210. In any event, it appears the ATC system broke down but TCASII worked as advertised. Although 1000 ft of separation existed at all times, it might have been a different story if other aircraft had been at FL240 or FL250.

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Original NASA ASRS Text

Title: CAPT OF ACR MLG ACFT DIVERTED FROM ASSIGNED ALT IN RESPONSE TO TCASII RA RESULTING IN LTSS.

Narrative: A LARGE WX SYS COVERED CENTRAL FL INVOLVING MODERATE TURB AND MODERATE ICING. ALL ACFT IN THE AREA HAD TO DEVIATE TO THE E TO CIRCUMVENT WX WHILE SIMULTANEOUSLY SEEKING LOWER ALTS FOR SMOOTHER RIDES. THE CTLR WAS EXTREMELY BUSY ISSUING TURNS, DSCNTS AND FREQ CHANGES ALMOST CONSTANTLY. IT WAS DIFFICULT TO XMIT WITHOUT STEPPING ON HIM. WE WERE DEVIATING E TO AN OPENING IN THE LINE OF WX AFTER HAVING DSNDED FROM FL330 (MODERATE TURB) TO FL230 (LIGHT TO MODERATE TURB). AS WE REACHED THE OPENING (20- 30 MI DEV AS APPROVED BY ATC), CTLR DIRECTED A TURN TO 340 DEGS, SOON AFTER WHICH THERE WAS A CTLR CHANGE. THE NEW CTLR DIRECTED US TO DO A 180 DEG TURN TOWARD PIE. JUST AS WE REACHED THE NEW HDG SBOUND AT FL230, ACFT DIRECTLY IN FRONT OF US AT FL210 HDG TOWARD US BEGAN AN ATC DIRECTED CLB. THIS ACFT WAS NOT RPTED ON OUR ATC FREQ. TCASII IMMEDIATELY DISPLAYED AN RA WITH THE AURAL ALERT 'CLB, CLB.' THE FLY-TO ARC WAS RED EVERYWHERE EXCEPT FOR A SMALL GREEN ARC FROM APPROX 3500 FPM TO 4000 FPM. WE BEGAN A CLB WHILE TRYING TO BURN THROUGH CONSTANT CHATTER TO DECLARE EMER. IN THE CLB WE SQUAWKED 7700 AND CONTINUED TO ATTEMPT CALLS TO ATC. RA REMAINED UNTIL REACHING FL250 AT WHICH TIME ATC ASKED IF OUR EMER WAS OVER AND DIRECTED US BACK DOWN TO FL230. (THE OTHER ACFT HAD LEVELED OFF AT FL220.) WE HAD TURNED SLIGHTLY (APPROX 30 DEGS) IN THE CLB SO WE ALSO RESUMED OUR HDG AS DIRECTED TOWARDS PIE. WE EVENTUALLY CLRED THE WX AND FURTHER DSCNT TO 11000 FT RESULTED IN LEAVING TURB AT APPROX FL200. WE ARRIVED IN RSW WITHOUT FURTHER INCIDENT. CONCLUSION: DUE TO WX, TURB AND NUMBER OF ACFT, ATC BECAME OVERLOADED, SO MUCH SO THAT SOME ACFT REVERSED COURSE AND RETURNED TO THEIR POINT OF ORIGIN. RA MIGHT HAVE BEEN AGGRAVATED BY OTHER ACFT'S AGGRESSIVE CLB TO FL220. PERHAPS HE WAS GETTING A POOR RIDE AT FL210. IN ANY EVENT, IT APPEARS THE ATC SYS BROKE DOWN BUT TCASII WORKED AS ADVERTISED. ALTHOUGH 1000 FT OF SEPARATION EXISTED AT ALL TIMES, IT MIGHT HAVE BEEN A DIFFERENT STORY IF OTHER ACFT HAD BEEN AT FL240 OR FL250.

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.