Air carrier X TCASII TA RA had less than standard separation from unknown aircraft. Evasive action t...

Attributes
ACN	299892
Time
Date	199503
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : smo
State Reference	CA
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : lax
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 240
ASRS Report	299892
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action other
Consequence	faa : investigated
Miss Distance	horizontal : 6000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X on approach to lax from the north, sadde 5 arrival, 2 identical targets appeared on TCASII 5-10 mi at 1-2 O'clock position. We were level at 10000 ft, targets initially 9300 ft continuing to climb. It became a single target, advisory went from TA to RA, with a descend command. During descent ATC was advised and queried. They seemed as surprised as we were. They responded with a frantic climb command. As we were in IMC, we could see nothing. We advised ATC of our RA command to descend, they came back with another frantic climb command. We began a climb immediately. Shortly thereafter, received a clear of conflict. In this situation, IMC, no visual clues, we were receiving opposing information from 2 different sources. We don't know how close we came. This is an interesting and hopefully unique situation that has really not been addressed. Callback conversation with reporter revealed the following information: reporter was informed the controller handbook states a controller is not to intervene or countermand a TCASII RA instruction.

Original NASA ASRS Text

Title: ACR X TCASII TA RA HAD LTSS FROM UNKNOWN ACFT. EVASIVE ACTION TAKEN.

Narrative: ACR X ON APCH TO LAX FROM THE N, SADDE 5 ARR, 2 IDENTICAL TARGETS APPEARED ON TCASII 5-10 MI AT 1-2 O'CLOCK POS. WE WERE LEVEL AT 10000 FT, TARGETS INITIALLY 9300 FT CONTINUING TO CLB. IT BECAME A SINGLE TARGET, ADVISORY WENT FROM TA TO RA, WITH A DSND COMMAND. DURING DSCNT ATC WAS ADVISED AND QUERIED. THEY SEEMED AS SURPRISED AS WE WERE. THEY RESPONDED WITH A FRANTIC CLB COMMAND. AS WE WERE IN IMC, WE COULD SEE NOTHING. WE ADVISED ATC OF OUR RA COMMAND TO DSND, THEY CAME BACK WITH ANOTHER FRANTIC CLB COMMAND. WE BEGAN A CLB IMMEDIATELY. SHORTLY THEREAFTER, RECEIVED A CLR OF CONFLICT. IN THIS SIT, IMC, NO VISUAL CLUES, WE WERE RECEIVING OPPOSING INFO FROM 2 DIFFERENT SOURCES. WE DON'T KNOW HOW CLOSE WE CAME. THIS IS AN INTERESTING AND HOPEFULLY UNIQUE SIT THAT HAS REALLY NOT BEEN ADDRESSED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS INFORMED THE CTLR HANDBOOK STATES A CTLR IS NOT TO INTERVENE OR COUNTERMAND A TCASII RA INSTRUCTION.

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.

Air carrier X TCASII TA RA had less than standard separation from unknown aircraft. Evasive action taken.