Air carrier has TCASII RA, responds.

Attributes
ACN	249855
Time
Date	199308
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : gqe
State Reference	TN
Altitude	msl bound lower : 8000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mem
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	arrival star : star
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 220 flight time total : 6800 flight time type : 3000
ASRS Report	249855
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

At 10000 ft MSL at 250 KIAS over gqe on the STAR routing, TCASII gives a TA on a contact at our 1 O'clock position and 4 mi. The TA shows a collision course with '0' altitude differential, i.e., co-altitude. I, as PNF, query mem approach about the traffic. They said they had just picked up the contact. Before the controller could finish his statement, the TCASII issued an RA to descend, which is what we did. The traffic flew above us at 500 ft and we bottomed out 2000 ft below our clearance at 8000 ft MSL. I was talking to ATC the whole time. On the ground, talking to the RAPCON supervisor, I was told that the conflict was a VFR aircraft flying at the wrong altitude. They had just picked him up when we did, and were tracking him to destination. Lesson: TCASII works -- believe it, especially in level cruise. Perform the maneuver the system calls for.

Original NASA ASRS Text

Title: ACR HAS TCASII RA, RESPONDS.

Narrative: AT 10000 FT MSL AT 250 KIAS OVER GQE ON THE STAR ROUTING, TCASII GIVES A TA ON A CONTACT AT OUR 1 O'CLOCK POS AND 4 MI. THE TA SHOWS A COLLISION COURSE WITH '0' ALT DIFFERENTIAL, I.E., CO-ALT. I, AS PNF, QUERY MEM APCH ABOUT THE TFC. THEY SAID THEY HAD JUST PICKED UP THE CONTACT. BEFORE THE CTLR COULD FINISH HIS STATEMENT, THE TCASII ISSUED AN RA TO DSND, WHICH IS WHAT WE DID. THE TFC FLEW ABOVE US AT 500 FT AND WE BOTTOMED OUT 2000 FT BELOW OUR CLRNC AT 8000 FT MSL. I WAS TALKING TO ATC THE WHOLE TIME. ON THE GND, TALKING TO THE RAPCON SUPVR, I WAS TOLD THAT THE CONFLICT WAS A VFR ACFT FLYING AT THE WRONG ALT. THEY HAD JUST PICKED HIM UP WHEN WE DID, AND WERE TRACKING HIM TO DEST. LESSON: TCASII WORKS -- BELIEVE IT, ESPECIALLY IN LEVEL CRUISE. PERFORM THE MANEUVER THE SYS CALLS FOR.

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.