PIC of air carrier medium large transport fails to adhere to TCASII RA command when it is assumed to be a false warning with actual traffic sighted.

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Attributes
ACN	201264
Time
Date	199202
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ccv
State Reference	VA
Altitude	msl bound lower : 5800 msl bound upper : 6000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 7000 flight time type : 500
ASRS Report	201264
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 90 flight time total : 10000
ASRS Report	201263
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 18000 vertical : 800
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

While in descent to 6000 ft MSL, TCASII displayed 2 targets. 1 real at 1200 ft below and 1 at 200 ft below. During this distraction, aircraft sank to 5800 ft MSL. The target at 200 ft below (6000 ft MSL) was merging, but clearly none was there. The target at 1200 ft below (5000 ft MSL) had been called out by ATC. As the recovery to 6000 ft was initiated the TCASII was saying 'descend, descend, now'. That action would have possibly put us in serious conflict with the 5000 ft traffic. So we continued to climb slowly back to 6000 ft MSL and the target and commands disappeared. Subsequently our altitude was verified and the vector was changed from 160 degrees to 170 degrees by the controller to ensure separation. Supplemental information from acn 201263: center (wash) asked us to confirm altitude and changed the vector from 160 degrees to 170 degrees and advised us of small aircraft traffic that I had visual contact with at that time.

Original NASA ASRS Text

Title: PIC OF ACR MLG FAILS TO ADHERE TO TCASII RA COMMAND WHEN IT IS ASSUMED TO BE A FALSE WARNING WITH ACTUAL TFC SIGHTED.

Narrative: WHILE IN DSCNT TO 6000 FT MSL, TCASII DISPLAYED 2 TARGETS. 1 REAL AT 1200 FT BELOW AND 1 AT 200 FT BELOW. DURING THIS DISTR, ACFT SANK TO 5800 FT MSL. THE TARGET AT 200 FT BELOW (6000 FT MSL) WAS MERGING, BUT CLRLY NONE WAS THERE. THE TARGET AT 1200 FT BELOW (5000 FT MSL) HAD BEEN CALLED OUT BY ATC. AS THE RECOVERY TO 6000 FT WAS INITIATED THE TCASII WAS SAYING 'DSND, DSND, NOW'. THAT ACTION WOULD HAVE POSSIBLY PUT US IN SERIOUS CONFLICT WITH THE 5000 FT TFC. SO WE CONTINUED TO CLB SLOWLY BACK TO 6000 FT MSL AND THE TARGET AND COMMANDS DISAPPEARED. SUBSEQUENTLY OUR ALT WAS VERIFIED AND THE VECTOR WAS CHANGED FROM 160 DEGS TO 170 DEGS BY THE CTLR TO ENSURE SEPARATION. SUPPLEMENTAL INFO FROM ACN 201263: CTR (WASH) ASKED US TO CONFIRM ALT AND CHANGED THE VECTOR FROM 160 DEGS TO 170 DEGS AND ADVISED US OF SMA TFC THAT I HAD VISUAL CONTACT WITH AT THAT TIME.

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.