A320
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1
Distraction; Human-Machine Interface; Situational Awareness
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Procedure; Human Factors
Aircraft X was an aircraft landing ONT. He was vectored north away from the usual initial fix on the STAR for the SCBBY1 to separate him for other traffic underneath him so he may descend. I APREQd him direct SCBBY for SCBBY1 arrival with Springs sector (combined) and it was approved. Normally from the initial fix; the aircraft descends via with no bottom altitude. I expected this to be ok and didn't coordinate an altitude and was not told to maintain anything specific. I descended him via the arrival and initiated a handful. A few minutes later the sectors were combined for midnight configuration. The relieving controller forgot that Aircraft X was still on the ZLA frequency and removed it from her scope. The aircraft continued to descend via below the MIAs and Springs called and told her to stop his descent which she did. The aircraft was then switched to the appropriate frequency An altitude should have been coordinated by either myself or Springs sector to ensure this doesn't happen again.
ZLA Center Controller reported that an aircraft was forgotten during a shift configuration changed and dropped by accident.