Close encounter for air carrier widebody transport on descent into san.

Attributes
ACN	180043
Time
Date	199105
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : mzb airport : san
State Reference	CA
Altitude	msl bound lower : 10700 msl bound upper : 11300
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute : on vectors enroute : direct enroute airway : san
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 45 flight time total : 10000
ASRS Report	180034
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : undershoot altitude deviation : excursion from assigned altitude conflict : airborne less severe other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : took evasive action other
Consequence	faa : reviewed incident with flight crew Other
Miss Distance	horizontal : 6000 vertical : 400
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We were on a flight from dfw and descending into san. Cleared to cross 40 east of mzb at 10000' and 250 KTS (pillo). Descending through 11000', ATC called traffic Y 12 O'clock; turn left 20 degrees. This was followed immediately by a TA, then RA on TCAS. Descent was stopped at 10700-10800', then an immediate climb to 11300'. TCAS changed to 'climb monitor climb.' TCAS altitude of traffic showed 10400', then clear of traffic. The climb and turn cleared traffic. Traffic was never sighted and it happened so fast that exact azimuth of traffic was not noted by us, except by TCAS, and appeared right in front of us in the 40 mi scale. I believe TCAS may have helped avoid the VFR traffic Y at 10400'. The controller made no mention of how close it was. TCAS may have saved our lives!

Original NASA ASRS Text

Title: CLOSE ENCOUNTER FOR ACR WDB ON DESCENT INTO SAN.

Narrative: WE WERE ON A FLT FROM DFW AND DSNDING INTO SAN. CLRED TO CROSS 40 E OF MZB AT 10000' AND 250 KTS (PILLO). DSNDING THROUGH 11000', ATC CALLED TFC Y 12 O'CLOCK; TURN LEFT 20 DEGS. THIS WAS FOLLOWED IMMEDIATELY BY A TA, THEN RA ON TCAS. DSNT WAS STOPPED AT 10700-10800', THEN AN IMMEDIATE CLB TO 11300'. TCAS CHANGED TO 'CLB MONITOR CLB.' TCAS ALT OF TFC SHOWED 10400', THEN CLR OF TFC. THE CLB AND TURN CLRED TFC. TFC WAS NEVER SIGHTED AND IT HAPPENED SO FAST THAT EXACT AZIMUTH OF TFC WAS NOT NOTED BY US, EXCEPT BY TCAS, AND APPEARED RIGHT IN FRONT OF US IN THE 40 MI SCALE. I BELIEVE TCAS MAY HAVE HELPED AVOID THE VFR TFC Y AT 10400'. THE CTLR MADE NO MENTION OF HOW CLOSE IT WAS. TCAS MAY HAVE SAVED OUR LIVES!

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.