B767 crew and an unknown aircraft had an near midair collision in ZOA class east airspace.

Attributes
ACN	592491
Time
Date	200308
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : torch
State Reference	CA
Altitude	msl bound lower : 11000 msl bound upper : 12300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa.artcc
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent : vacating altitude
Route In Use	arrival star : el nino
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zoa.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise : level
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 50 flight time total : 4800 flight time type : 1800
ASRS Report	592491
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : nmac non adherence : far non adherence : published procedure non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 0 vertical : 300
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

After descending to 11000 ft, we received a TA followed by a 'climb' annunciation. Captain complied and we topped out at 12300 ft. We never saw other aircraft except for on our cdti. Aircraft appeared to approach us from 11 O'clock position and pass directly underneath us. Our heading at the time was approximately 250 degrees.

Original NASA ASRS Text

Title: B767 CREW AND AN UNKNOWN ACFT HAD AN NMAC IN ZOA CLASS E AIRSPACE.

Narrative: AFTER DSNDING TO 11000 FT, WE RECEIVED A TA FOLLOWED BY A 'CLB' ANNUNCIATION. CAPT COMPLIED AND WE TOPPED OUT AT 12300 FT. WE NEVER SAW OTHER ACFT EXCEPT FOR ON OUR CDTI. ACFT APPEARED TO APPROACH US FROM 11 O'CLOCK POS AND PASS DIRECTLY UNDERNEATH US. OUR HDG AT THE TIME WAS APPROX 250 DEGS.

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.