Nct TRACON controller reported working four sectors and failed to notice an aircraft descending to a...

Attributes
ACN	1408285
Time
Date	201612
Local Time Of Day	0601-1200
Place
Locale Reference	NCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Transport
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft Low Wing 2 Eng Retractable Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	STAR PXN4
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 12
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Narrative:

I was working four sectors combined. Traffic initially was slow. Aircraft X was enroute to mry; IFR; at 10000 feet. Aircraft Y was handed off IFR at 10000 feet; enroute to oak. As is usual; the airspace got busy very rapidly. This combined with landline calls and vectoring various airport arrivals I got busy very quickly and was playing catch up. I told the controller in charge (controller in charge) that I needed another sector opened. Aircraft Y stated that he was starting the descent for oak on the pxn arrival. At this point I saw the position of aircraft X and aircraft Y and realized I had forgotten to descend aircraft Y leading to a loss of separation of 2.04 miles and 200 feet.I hear the younger controllers complain about opening sectors constantly. Too bad! Stop the practice of keeping morgan and turlock combined all day. This leads to frequency overlap as well as controller overload.

Original NASA ASRS Text

Title: NCT TRACON Controller reported working four sectors and failed to notice an aircraft descending to an altitude into conflict with another aircraft; resulting in a loss of separation.

Narrative: I was working four sectors combined. Traffic initially was slow. Aircraft X was enroute to MRY; IFR; at 10000 feet. Aircraft Y was handed off IFR at 10000 feet; enroute to OAK. As is usual; the airspace got busy very rapidly. This combined with landline calls and vectoring various airport arrivals I got busy very quickly and was playing catch up. I told the Controller in Charge (CIC) that I needed another sector opened. Aircraft Y stated that he was starting the descent for OAK on the PXN arrival. At this point I saw the position of Aircraft X and Aircraft Y and realized I had forgotten to descend Aircraft Y leading to a loss of separation of 2.04 miles and 200 feet.I hear the younger controllers complain about opening sectors constantly. Too bad! Stop the practice of keeping Morgan and Turlock combined ALL day. This leads to frequency overlap as well as controller overload.

Data retrieved from NASA's ASRS site 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.

Nct TRACON controller reported working four sectors and failed to notice an aircraft descending to an altitude into conflict with another aircraft; resulting in a loss of separation.