A TRACON controller reported they handed off an aircraft late and had to descend the traffic for con...

Narrative:

Aircraft X departed IFR to the northeast. The aircraft checked on turning to a 090 heading and climbing to 3000 feet. I instructed the aircraft to join V334 and climb to 5000 feet. A few minutes later I realized I had pointed the aircraft out to sjc who was holding departures instead of handing aircraft X off to the adjacent sector. I initiated the hand off and called the sector. They had me descend aircraft X to 4000 feet and turn left heading 330. As the controller was saying this I observed two B737's westbound descending out of 6000 feet. I instructed aircraft X to descend to 4000 feet and turn left to 330. I also called traffic on the first B737 which the pilot reported in sight. I instructed aircraft X to maintain visual separation. I then observed aircraft X at 3700 feet at which time I reiterated 4000 feet which the pilot read back. It appeared to me aircraft X was correcting and was not in any danger with the terrain. I called traffic on a VFR aircraft at 3500 feet and shipped the aircraft. It did not occur to me to issue a low altitude alert.

Original NASA ASRS Text

Title: A TRACON Controller reported they handed off an aircraft late and had to descend the traffic for converging traffic. The aircraft descended below the assigned altitude below the Minimum Vectoring Altitude into conflict with a target.

Narrative: Aircraft X departed IFR to the northeast. The aircraft checked on turning to a 090 heading and climbing to 3000 feet. I instructed the aircraft to join V334 and climb to 5000 feet. A few minutes later I realized I had pointed the aircraft out to SJC who was holding departures instead of handing Aircraft X off to the adjacent sector. I initiated the hand off and called the sector. They had me descend Aircraft X to 4000 feet and turn left heading 330. As the controller was saying this I observed two B737's westbound descending out of 6000 feet. I instructed Aircraft X to descend to 4000 feet and turn left to 330. I also called traffic on the first B737 which the pilot reported in sight. I instructed Aircraft X to maintain visual separation. I then observed Aircraft X at 3700 feet at which time I reiterated 4000 feet which the pilot read back. It appeared to me Aircraft X was correcting and was not in any danger with the terrain. I called traffic on a VFR aircraft at 3500 feet and shipped the aircraft. It did not occur to me to issue a low altitude alert.

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.

Attributes
ACN	1672464
Time
Date	201908
Local Time Of Day	0001-0600
Place
Locale Reference	NCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Medium Large Transport
Flight Phase	Climb
Route In Use	Airway V334
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Developmental
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 0.6
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Conflict Airborne Conflict Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

A TRACON controller reported they handed off an aircraft late and had to descend the traffic for converging traffic. The aircraft descended below the assigned altitude below the minimum vectoring altitude into conflict with a target.