A carj crew, while cruising at FL260, responded to a TCASII 'descend' RA.

Attributes
ACN	533511
Time
Date	200112
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : mol.vor
State Reference	VA
Altitude	msl single value : 26000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 4500 flight time type : 2000
ASRS Report	533511
Person 2
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne critical non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : exited adverse environment
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 12000 vertical : 1000
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance

Narrative:

Air carrier X flight XXXX operated ric-cvg on dec/mon/01. At XA35Z and west of the mol VOR, ATC informed us of descending traffic. No visual contact was established. A few seconds later, we received a TCASII RA to 'descend.' we were at our assigned cruise altitude of FL260 and the intruder aircraft was at our 2 O'clock position and descending. The first officer (PF) followed the RA commands and descended 500 ft. At no time was visual contact established with intruder aircraft. We informed ATC of the situation and action taken, and returned to our assigned altitude. The vsi RA commanded a 1700 FPM descent. I do not believe there was a collision threat from the aircraft symbols on the TCASII display. Intruder aircraft passed approximately 2 mi north of us. We were wbound.

Original NASA ASRS Text

Title: A CARJ CREW, WHILE CRUISING AT FL260, RESPONDED TO A TCASII 'DSND' RA.

Narrative: ACR X FLT XXXX OPERATED RIC-CVG ON DEC/MON/01. AT XA35Z AND W OF THE MOL VOR, ATC INFORMED US OF DSNDING TFC. NO VISUAL CONTACT WAS ESTABLISHED. A FEW SECONDS LATER, WE RECEIVED A TCASII RA TO 'DSND.' WE WERE AT OUR ASSIGNED CRUISE ALT OF FL260 AND THE INTRUDER ACFT WAS AT OUR 2 O'CLOCK POS AND DSNDING. THE FO (PF) FOLLOWED THE RA COMMANDS AND DSNDED 500 FT. AT NO TIME WAS VISUAL CONTACT ESTABLISHED WITH INTRUDER ACFT. WE INFORMED ATC OF THE SIT AND ACTION TAKEN, AND RETURNED TO OUR ASSIGNED ALT. THE VSI RA COMMANDED A 1700 FPM DSCNT. I DO NOT BELIEVE THERE WAS A COLLISION THREAT FROM THE ACFT SYMBOLS ON THE TCASII DISPLAY. INTRUDER ACFT PASSED APPROX 2 MI N OF US. WE WERE WBOUND.

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.