Air carrier X received false TCASII TA RA non adherence to ATC clearance. Pilot deviation.

Attributes
ACN	194516
Time
Date	199111
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mod
State Reference	CA
Altitude	msl bound lower : 28000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
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 : 15000 flight time type : 200
ASRS Report	194516
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Air Traffic Incident	Pilot Deviation

Narrative:

Air carrier X FL280, cruise, received RA 'descend' in IMC. Descended to FL265 and advised ATC (ZOA). Target appeared on TCASII display level 3 O'clock, 5 mi and closing. Could not confirm visually. Target disappeared from display when superimposed over aircraft symbol. ATC advised of situation and cleared to climb back to FL280. ATC said 'no paperwork required.' callback conversation with reporter revealed the following information: reporter stated at the time of the incident the flight crew was in VMC under an overcast. The flight crew first received a TA then an RA. Company policy is mandatory response to RA. After evasive action by descent flight crew reporter talked to ARTCC controller and there was no traffic. Reporter feels it was a false target.

Original NASA ASRS Text

Title: ACR X RECEIVED FALSE TCASII TA RA NON ADHERENCE TO ATC CLRNC. PLTDEV.

Narrative: ACR X FL280, CRUISE, RECEIVED RA 'DSND' IN IMC. DSNDED TO FL265 AND ADVISED ATC (ZOA). TARGET APPEARED ON TCASII DISPLAY LEVEL 3 O'CLOCK, 5 MI AND CLOSING. COULD NOT CONFIRM VISUALLY. TARGET DISAPPEARED FROM DISPLAY WHEN SUPERIMPOSED OVER ACFT SYMBOL. ATC ADVISED OF SITUATION AND CLRED TO CLB BACK TO FL280. ATC SAID 'NO PAPERWORK REQUIRED.' CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED AT THE TIME OF THE INCIDENT THE FLC WAS IN VMC UNDER AN OVCST. THE FLC FIRST RECEIVED A TA THEN AN RA. COMPANY POLICY IS MANDATORY RESPONSE TO RA. AFTER EVASIVE ACTION BY DSCNT FLC RPTR TALKED TO ARTCC CTLR AND THERE WAS NO TFC. RPTR FEELS IT WAS A FALSE TARGET.

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.