CL600 flight crew responded to TCAS resolution advisory during cruise. Flight crew believes the intr...

Attributes
ACN	757792
Time
Date	200710
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ztl.artcc
State Reference	GA
Altitude	msl single value : 29000
Environment
Flight Conditions	VMC
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
Route In Use	arrival star : johns
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : ztl.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	757792
Events
Anomaly	conflict : airborne critical
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took evasive action
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

While level at FL290 approaching flabb intersection on arrival to clt (JOHNS1) we received a TCAS TA; then an RA commanding us to climb at 1000 FPM. I immediately complied with the RA. The command continued at 1000 FPM until reaching FL300. We advised ATC. We received no TA from ZTL. I think the B737 below us was responding to his own RA and climbed to our altitude. The B737 climbed up to our assigned altitude; possibly through it; and passed directly below us as seen by first officer and as shown on our mfd. I firmly believe; both immediately after the event; and now after reflection; that the TCAS unit in our aircraft saved the lives of many people. Not sure exactly why this event occurred. However; as stated above the B737 was responding to his own RA and that is what caused ours. There could be numerous reasons for his RA; such as another aircraft altitude deviation or a lack of separation error by ATC. Unsure how to avoid this event in the future. One thing I know for sure is that TCAS saved us from disaster. I would recommend a policy to never fly without TCAS being operative. It is currently allowed to be MEL'ed.

Original NASA ASRS Text

Title: CL600 FLT CREW RESPONDED TO TCAS RESOLUTION ADVISORY DURING CRUISE. FLT CREW BELIEVES THE INTRUDING ACFT WAS ALSO RESPONDING TO AN RA.

Narrative: WHILE LEVEL AT FL290 APCHING FLABB INTXN ON ARR TO CLT (JOHNS1) WE RECEIVED A TCAS TA; THEN AN RA COMMANDING US TO CLB AT 1000 FPM. I IMMEDIATELY COMPLIED WITH THE RA. THE COMMAND CONTINUED AT 1000 FPM UNTIL REACHING FL300. WE ADVISED ATC. WE RECEIVED NO TA FROM ZTL. I THINK THE B737 BELOW US WAS RESPONDING TO HIS OWN RA AND CLBED TO OUR ALT. THE B737 CLBED UP TO OUR ASSIGNED ALT; POSSIBLY THROUGH IT; AND PASSED DIRECTLY BELOW US AS SEEN BY FO AND AS SHOWN ON OUR MFD. I FIRMLY BELIEVE; BOTH IMMEDIATELY AFTER THE EVENT; AND NOW AFTER REFLECTION; THAT THE TCAS UNIT IN OUR ACFT SAVED THE LIVES OF MANY PEOPLE. NOT SURE EXACTLY WHY THIS EVENT OCCURRED. HOWEVER; AS STATED ABOVE THE B737 WAS RESPONDING TO HIS OWN RA AND THAT IS WHAT CAUSED OURS. THERE COULD BE NUMEROUS REASONS FOR HIS RA; SUCH AS ANOTHER ACFT ALTDEV OR A LACK OF SEPARATION ERROR BY ATC. UNSURE HOW TO AVOID THIS EVENT IN THE FUTURE. ONE THING I KNOW FOR SURE IS THAT TCAS SAVED US FROM DISASTER. I WOULD RECOMMEND A POLICY TO NEVER FLY WITHOUT TCAS BEING OPERATIVE. IT IS CURRENTLY ALLOWED TO BE MEL'ED.

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.

CL600 flight crew responded to TCAS resolution advisory during cruise. Flight crew believes the intruding aircraft was also responding to an RA.