Nct controllers reported thinking an IFR aircraft was VFR and allowed it to proceed on its own navig...

Attributes
ACN	1420148
Time
Date	201701
Local Time Of Day	1201-1800
Place
Locale Reference	NCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft Low Wing 1 Eng Retractable Gear
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Person 2
Function	Coordinator
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 5
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT

Narrative:

Aircraft X checked on my frequency at 6000 feet. After giving control instructions to other aircraft I came back to aircraft X; issued the oak altimeter; and asked him his requested altitude. He responded that his last assigned altitude was 6000 feet. I then asked him what his requested altitude was and he responded that he would take whatever altitude I could give him. I replied that I can give him anything he wants. He then stated how about 3000 feet. I responded that altitude was his discretion. I handed aircraft X off to the next sector. At that point aircraft X was descending out of 4000 feet in a 4000 foot minimum vectoring altitude (MVA). He continued to descend through a 5000 foot MVA down to 3000 feet. The receiving controller did not catch the MVA violation. During this entire incident I did not register that aircraft X was IFR and I believed that he was VFR the entire time I was working him.the low altitude alert did not go off either in the 4000 foot MVA or the 5000 foot MVA. I would recommend increased diligence of data blocks during busy sessions; and if busy ask for a hand-off.

Original NASA ASRS Text

Title: NCT controllers reported thinking an IFR aircraft was VFR and allowed it to proceed on its own navigation below the MVA.

Narrative: Aircraft X checked on my frequency at 6000 feet. After giving control instructions to other aircraft I came back to Aircraft X; issued the OAK altimeter; and asked him his requested altitude. He responded that his last assigned altitude was 6000 feet. I then asked him what his requested altitude was and he responded that he would take whatever altitude I could give him. I replied that I can give him anything he wants. He then stated how about 3000 feet. I responded that altitude was his discretion. I handed Aircraft X off to the next sector. At that point Aircraft X was descending out of 4000 feet in a 4000 foot Minimum Vectoring Altitude (MVA). He continued to descend through a 5000 foot MVA down to 3000 feet. The receiving controller did not catch the MVA violation. During this entire incident I did not register that Aircraft X was IFR and I believed that he was VFR the entire time I was working him.The low altitude alert did not go off either in the 4000 foot MVA or the 5000 foot MVA. I would recommend increased diligence of data blocks during busy sessions; and if busy ask for a hand-off.

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 controllers reported thinking an IFR aircraft was VFR and allowed it to proceed on its own navigation below the MVA.