CL65 flight crew reports TCAS RA with unknown aircraft at FL330; 80 northwest of gqo.

Attributes
ACN	781684
Time
Date	200804
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : gqo.vortac
State Reference	TN
Altitude	msl single value : 33000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : ztl.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : vacating altitude
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 7200 flight time type : 3500
ASRS Report	781684
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	conflict : airborne critical
Independent Detector	atc equipment other atc equipment : radar aircraft equipment : tcas other controllera
Resolutory Action	controller : issued advisory flight crew : took evasive action
Miss Distance	horizontal : 0 vertical : 700
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

At FL330 approximately 80 mi northwest of gqo heading about 150 degrees in IMC; we were cleared to FL240. ATC advised us of a target at 10-11 O'clock position nwbound at 1500 ft below us. He said it was probably an erroneous target. We initially started to descend but it appeared to us to be a real target and it was climbing. We stopped the descent at FL327 to be sure there would be no problem. We then received a TA and (I think) advised ATC. We then received an RA with climb instructions of 2100 FPM. We immediately complied with the RA and advised ATC. The other target continued to climb and leveled at FL330 below us. When we received the 'clear of conflict' message from TCAS we were at about FL337. We then told ATC we were clear of the target and continuing our descent to FL240. ATC never made another mention of the incident and things happened so quickly; and we were so fixed on the incident and continuing to ZZZ that we never had a chance to inquire about the incident with ATC. I feel this target was an actual aircraft that ATC didn't know about and if we had continued the descent the results could have been an incursion or worse.

Original NASA ASRS Text

Title: CL65 FLT CREW REPORTS TCAS RA WITH UNKNOWN ACFT AT FL330; 80 NW OF GQO.

Narrative: AT FL330 APPROX 80 MI NW OF GQO HDG ABOUT 150 DEGS IN IMC; WE WERE CLRED TO FL240. ATC ADVISED US OF A TARGET AT 10-11 O'CLOCK POS NWBOUND AT 1500 FT BELOW US. HE SAID IT WAS PROBABLY AN ERRONEOUS TARGET. WE INITIALLY STARTED TO DSND BUT IT APPEARED TO US TO BE A REAL TARGET AND IT WAS CLBING. WE STOPPED THE DSCNT AT FL327 TO BE SURE THERE WOULD BE NO PROB. WE THEN RECEIVED A TA AND (I THINK) ADVISED ATC. WE THEN RECEIVED AN RA WITH CLB INSTRUCTIONS OF 2100 FPM. WE IMMEDIATELY COMPLIED WITH THE RA AND ADVISED ATC. THE OTHER TARGET CONTINUED TO CLB AND LEVELED AT FL330 BELOW US. WHEN WE RECEIVED THE 'CLR OF CONFLICT' MESSAGE FROM TCAS WE WERE AT ABOUT FL337. WE THEN TOLD ATC WE WERE CLR OF THE TARGET AND CONTINUING OUR DSCNT TO FL240. ATC NEVER MADE ANOTHER MENTION OF THE INCIDENT AND THINGS HAPPENED SO QUICKLY; AND WE WERE SO FIXED ON THE INCIDENT AND CONTINUING TO ZZZ THAT WE NEVER HAD A CHANCE TO INQUIRE ABOUT THE INCIDENT WITH ATC. I FEEL THIS TARGET WAS AN ACTUAL ACFT THAT ATC DIDN'T KNOW ABOUT AND IF WE HAD CONTINUED THE DSCNT THE RESULTS COULD HAVE BEEN AN INCURSION OR WORSE.

Data retrieved from NASA's ASRS site as of May 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.