TCASII RA. - NASA ASRS

Attributes
ACN	281450
Time
Date	199408
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : san
State Reference	CA
Altitude	msl bound lower : 5000 msl bound upper : 5700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : san
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 15400 flight time type : 2000
ASRS Report	281450
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : became reoriented flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On final approach to san (5000 ft MSL and 6 NM out, approximately) our on-board TCASII commanded to several actions ranging from 'climb' to 'monitor vertical speed' in response to at least 2 targets displayed about 1 mi ahead. One of them was shown as 400 ft below us. The PF responded to the commands of TCASII until the targets' conflict was apparently resolved. Later, ATC advised us of a conflicting traffic above us. We advised them of our TCASII maneuver in response to apparent traffic and they replied that those targets were not on his radar and were possibly false. Although I personally have trusted the a- 320 TCASII system, this incident of apparent false has cast some doubts in my mind. ATC later stated that several false targets were reported in the area that morning.

Original NASA ASRS Text

Title: TCASII RA.

Narrative: ON FINAL APCH TO SAN (5000 FT MSL AND 6 NM OUT, APPROX) OUR ON-BOARD TCASII COMMANDED TO SEVERAL ACTIONS RANGING FROM 'CLB' TO 'MONITOR VERT SPD' IN RESPONSE TO AT LEAST 2 TARGETS DISPLAYED ABOUT 1 MI AHEAD. ONE OF THEM WAS SHOWN AS 400 FT BELOW US. THE PF RESPONDED TO THE COMMANDS OF TCASII UNTIL THE TARGETS' CONFLICT WAS APPARENTLY RESOLVED. LATER, ATC ADVISED US OF A CONFLICTING TFC ABOVE US. WE ADVISED THEM OF OUR TCASII MANEUVER IN RESPONSE TO APPARENT TFC AND THEY REPLIED THAT THOSE TARGETS WERE NOT ON HIS RADAR AND WERE POSSIBLY FALSE. ALTHOUGH I PERSONALLY HAVE TRUSTED THE A- 320 TCASII SYS, THIS INCIDENT OF APPARENT FALSE HAS CAST SOME DOUBTS IN MY MIND. ATC LATER STATED THAT SEVERAL FALSE TARGETS WERE RPTED IN THE AREA THAT MORNING.

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.