Near midair collision near oak, ca, between air carrier IFR and GA VFR aircraft.

Attributes
ACN	567643
Time
Date	200212
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : sgd.vortac
State Reference	CA
Altitude	msl single value : 10000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sck.tracon
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach
Route In Use	arrival star : marvn one
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : sck.tracon
Operator	general aviation : personal
Make Model Name	Beechcraft Single Piston Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
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 : 10000 flight time type : 7000
ASRS Report	567643
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 103 flight time total : 4500 flight time type : 1500
ASRS Report	567644
Events
Anomaly	conflict : nmac
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	other
Miss Distance	vertical : 500
Supplementary
Problem Areas	Airspace Structure ATC Human Performance Flight Crew Human Performance
Primary Problem	Airspace Structure

Narrative:

On the marvin arrival into oak at 10000 ft in the vicinity of groan intersection, we received a TA on TCASII. The traffic was co-altitude and opposite direction. The following sequence is best of my recollection. The first officer asked approach about the traffic. Approach told us to descend to 10000 ft. The first officer responded that we were already at 10000 ft. Meanwhile, an RA sounded to climb, and I disconnected the autoplt and started a slow climb. Approach came back with instructions to climb to 11000 ft. I picked up the bonanza at 10500 ft. He appeared to be level at 10000 ft, and initiated a left turn as he passed below us. Once cleared of traffic, we continued on the arrival. Supplemental information from acn #567644: PF (captain) took evasive action, and we cleared the v-tail bonanza by 500 ft. During conflict, approach control gave us conflicting information, telling us to descend to 10000 ft (into the traffic). We were already at 10000 ft. Strange thing was a similar conflict between an air carrier MD80 and another air carrier a few mins before this happened to us. Same controller.

Original NASA ASRS Text

Title: NMAC NEAR OAK, CA, BTWN ACR IFR AND GA VFR ACFT.

Narrative: ON THE MARVIN ARR INTO OAK AT 10000 FT IN THE VICINITY OF GROAN INTXN, WE RECEIVED A TA ON TCASII. THE TFC WAS CO-ALT AND OPPOSITE DIRECTION. THE FOLLOWING SEQUENCE IS BEST OF MY RECOLLECTION. THE FO ASKED APCH ABOUT THE TFC. APCH TOLD US TO DSND TO 10000 FT. THE FO RESPONDED THAT WE WERE ALREADY AT 10000 FT. MEANWHILE, AN RA SOUNDED TO CLB, AND I DISCONNECTED THE AUTOPLT AND STARTED A SLOW CLB. APCH CAME BACK WITH INSTRUCTIONS TO CLB TO 11000 FT. I PICKED UP THE BONANZA AT 10500 FT. HE APPEARED TO BE LEVEL AT 10000 FT, AND INITIATED A L TURN AS HE PASSED BELOW US. ONCE CLRED OF TFC, WE CONTINUED ON THE ARR. SUPPLEMENTAL INFO FROM ACN #567644: PF (CAPT) TOOK EVASIVE ACTION, AND WE CLRED THE V-TAIL BONANZA BY 500 FT. DURING CONFLICT, APCH CTL GAVE US CONFLICTING INFO, TELLING US TO DSND TO 10000 FT (INTO THE TFC). WE WERE ALREADY AT 10000 FT. STRANGE THING WAS A SIMILAR CONFLICT BTWN AN ACR MD80 AND ANOTHER ACR A FEW MINS BEFORE THIS HAPPENED TO US. SAME CTLR.

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.