Commercial Fixed Wing
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural FAR
Flight Crew Returned To Gate; General Maintenance Action
Human Factors
After leaving the gate and engine start our flight attendants called us and notified a passenger had left batteries in their gate check bag. The passenger had their carry on that wouldn't fit in an overhead so a gate agent checked the bag. In their bag they had two lithium ion batteries (two drill batteries) loose not inserted in a drill. We talked to dispatch and referenced FOM/Hazmat Manual and determined with [Operations] we needed to gate return to remove the bag from the cargo hold and either find room in the cabin for the bag or keep the batteries with the passenger. We Gate returned; retrieved the bag/batteries; and refueled. And all decided we could make room in the cabin for the bag. I spoke again with Dispatch and [Operations Manager] regarding the passenger and Carry-On being back in the cabin and all signs pointed to us following the rules on this situation. We left with an uneventful flight. After review it seems like conflicting information on if we broke a sterile TSA program rule or not. A recent chief pilot newsletter talks about a commuting pilot not able to retrieve a checked bag from the cargo hold. This bag had been screened by TSA and considered sterile. I regret not confirming that piece of information on if we should have removed the passenger; and the bag all together and have them re-screened. As frustrating as the timing was on the passenger realizing they had batteries in their bag; they did the right thing by bringing this to our attention. This was a first for me; if there's anything I overlooked or missed feedback is welcome.Knowing what I know now; I wished I would have been more familiar with this type of situation and if the bag could be returned to the cabin. In hindsight I would have removed the batteries and gave them to the passenger to keep on their person. Ultimately; leave the carry-on in the cargo hold.
Air carrier Captain reported that a customer gate-checked a bag with lithium batteries; resulting in a return to the gate.