Date: 201911
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Confusion; Other / Unknown
Anomaly: Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Crew
When detected: Pre-flight
Result: General None Reported / Taken
Contributing factors: Chart Or Publication; Company Policy
Primary problem: Chart Or Publication

Narrative: I observed one of our pre-board passengers remove the battery pack from her scooter and bring it on the aircraft. I thought this was unusual and was not sure whether this was approved; or not. After she had found a seat; I approached the passenger and asked if I could look at her battery. I determined that it was a Lithium Ion battery pack. I thanked her; placed the battery back in her carry-on bag and stowed the bag in the overhead. I then asked my First Officer to look up the battery section in the FOM.He pulled up FOM. I located 'Wheelchairs (non-collapsible) and other mobility aids powered by lithium batteries.' I determined that it was not permitted in carryon baggage and that it should be secured to the scooter and placed in the cargo bin. I asked the Operations Agent to request a Supervisor to assist me when I spoke to the passenger.I explained the situation to the Supervisor and then we proceeded to talk to the passenger. I apologized for the inconvenience; and explained our procedures. She was visibly upset and concerned about the condition the battery would be in upon arrival in ZZZ1. She explained that she travels frequently and this was the first time this had happened. She said several other pilots had told her that she had to put it in her carryon. I again apologized for the confusion and retrieved the battery. Per FOM 'Wheelchairs and Other Assistance Devices;' the Supervisor secured the battery back onto the scooter; which was then taken to the ramp. The Supervisor said he would make a note of all this in the passenger's reservations.Once we arrived in ZZZ1 and the jetway was pulled up; I went down to the ramp to retrieve the scooter. I watched the Ramp Agent reattach the cords from the battery to the scooter and then I carried the scooter up into the jetway where the passenger was waiting.Upon further review; there seems to be a contradiction in the FOM. I did not determine the size of the battery. However; there is a note which states 'Single Battery-Not exceeding 300Wh' NOT permitted in or as checked baggage but IS permitted in or as carryon baggage refer to note 6. Note 6 states; 'Batteries must be removed; properly protected; and transported in the cabin. After batteries are removed; the device itself can be transported in checked or carryon baggage; size permitting.'Had I not witnessed the passenger carry the battery onboard; I would have not known there was an issue. This was the first time I had seen this done. Normally; the battery remains attached to the scooter. I am now unsure which procedure is correct. I followed the procedure I determined to be correct at the time. Why the seemingly contradictory procedures?




Synopsis: B737-700 Captain reported an inconsistency between FOM Hazmat chapter narrative and Tables utilized for handling of Lithium Ion battery powered wheelchairs.