Air carrier X TCASII evasive action taken from aircraft Y possible false target.

Attributes
ACN	257166
Time
Date	199311
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : smo
State Reference	CA
Altitude	msl bound lower : 10100 msl bound upper : 11300
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : lax
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
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 : 27000 flight time type : 800
ASRS Report	257166
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : undershoot conflict : nmac non adherence : required legal separation non adherence : clearance other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 0 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

Air carrier X descending from 12000 to 10000 and being given delay vectors. West of smo VOR we got a TCASII TA. We were in a right turn toward the traffic Y. We were leveling at approximately 10100 ft and traffic 100 ft below us. First officer reversed vertical flight path and climbed back up through approximately 11200 and turned left, away from traffic. ATC radio frequency so congested we were unable to 'break through' and tell what our actions were. Further clearance was a 090 heading and descent to 7000 ft. We never got a TA/RA alert, but felt the altitude separation and turn into traffic demanded immediate action. First officer felt the volume level of 'traffic, traffic' was too low and at first did not understand 'traffic.' relief captain and first officer in cockpit were very helpful in programming mode control panel.

Original NASA ASRS Text

Title: ACR X TCASII EVASIVE ACTION TAKEN FROM ACFT Y POSSIBLE FALSE TARGET.

Narrative: ACR X DSNDING FROM 12000 TO 10000 AND BEING GIVEN DELAY VECTORS. W OF SMO VOR WE GOT A TCASII TA. WE WERE IN A R TURN TOWARD THE TFC Y. WE WERE LEVELING AT APPROX 10100 FT AND TFC 100 FT BELOW US. FO REVERSED VERT FLT PATH AND CLBED BACK UP THROUGH APPROX 11200 AND TURNED L, AWAY FROM TFC. ATC RADIO FREQ SO CONGESTED WE WERE UNABLE TO 'BREAK THROUGH' AND TELL WHAT OUR ACTIONS WERE. FURTHER CLRNC WAS A 090 HDG AND DSCNT TO 7000 FT. WE NEVER GOT A TA/RA ALERT, BUT FELT THE ALT SEPARATION AND TURN INTO TFC DEMANDED IMMEDIATE ACTION. FO FELT THE VOLUME LEVEL OF 'TFC, TFC' WAS TOO LOW AND AT FIRST DID NOT UNDERSTAND 'TFC.' RELIEF CAPT AND FO IN COCKPIT WERE VERY HELPFUL IN PROGRAMMING MODE CTL PANEL.

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.