EMB ERJ 135 ER/LR
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Private; Flight Crew Commercial
Confusion; Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Airspace Structure; Procedure
Aircraft X was being vectored to the west for the ILS 12 and was level at 3;200 [feet] and instructed to descend to 3;000 [feet]. This engaged the aircraft GPWS and an aural warning sounded. I began a climb from the assigned altitude of 3;000 [feet] to 3;200 [feet] and informed OAK approach. I descended from there; continuing the approach without conflict.
Upon arriving into OAK; the landing runways were switched from [Runway] 28R to [Runway] 12. We were vectored off of the arrival to be positioned for the ILS 12/visual. At 3;200 feet; we were asked to descend to 3;000 [feet]. Upon descending; we got a terrain warning and landing gear warning. We climbed back up to 3;200 feet to avoid conflict and advised ATC. ATC told us to descend to 3;000 [feet] when able. We complied when clear of conflict and continued on course.
EMB-135 flight crew reported a GPWS event during approach to OAK airport.