Date: 202104
Local time of day: 0601-1200
Location: ZZZ.Tower, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb; Takeoff / Launch
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Horizontal Stabilizer Trim
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Human-Machine Interface; Troubleshooting
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Separated Traffic; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; Flight Crew Diverted; Flight Crew Landed As Precaution; General Flight Cancelled / Delayed
Contributing factors: Aircraft; Equipment / Tooling
Primary problem: Aircraft

Narrative: All preflight items complete INCLUDING Main Electric STAB TRIM CUTOUT switch with normal results. Student Captain was Pilot flying for this leg. Shortly after Takeoff the PF commented that his electric trim switch was not working and asked me to try mine; which also did not work. I asked him if the elevator was working and he replied that it was and felt normal. We asked ATC to level off at 12;000 ft to work on a flight control issue and was approved. We did not ask for priority handling at this time...we engaged the A Autopilot successfully but shortly after the 'STAB OUT OF TRIM' light came on. As we began to look up the appropriate Non-normal; the PF disengaged the autopilot and tried to manually trim the stabilizer. Although he was successful it looked like it was difficult to rotate so I asked to give it a shot to feel the force required to rotate. The force required to rotate was abnormally high but did provide results and we were flying a trimmed aircraft at 240 knots. By now I was considering that a Jammed Flight Control (the stabilizer in this case) was the source of our STAB OUT OF TRIM  problem. So the first checklist we addressed was the Jammed or Restricted Flight Controls Non-normal and also the Jammed or Restricted Flight Controls procedure (the script/expanded explanation). Around this time we requested priority handling with ATC because checklist called for landing at nearest suitable airport. We were hoping that we might get electric trim back when moving STAB TRIM switch on pedestal to OVERRIDE. Did not happen. Called Dispatch with Maintenance Control on the line hoping for some systems expertise. Ended call with where we started. We began to discuss possible value of running STAB OUT OF TRIM checklist. We did. But before doing so we noted the hazard of running multiple checklists and capped our STAB TRIM OVERRIDE switch to normal. The Jammed Flight Control non normal resulted in moving both STAB  TRIM switches to CUTOUT but also called for landing at nearest suitable with Flaps 15. About this time we got on radio again with Maintenance Control; Dispatch and also the Flight Operations. Our hope was that Flight Operations might be able to get a Hydraulics of Flight Controls Maintenance expert on with us. We discussed both checklists and Flight Operations talked about the potential effect of slower speeds. This call ended with general consensus we were on the best track and we discussed whether to land sooner or burn down to below Max landing weight. Because we felt the aircraft was stable and our condition was not likely to get worse we chose to burn fuel. I talked to PF and told him it would be prudent for me to do landing since that would be his first one from left seat in aircraft. We briefed our arrival plan which included our trim plan as we reduced airspeed and extended gear and flaps. As we descended and slowed we reminded ATC of need for priority handling equipment. Only significant thing to report was that by the time we had fully configured and slowed to final approach speed it was extremely difficult to trim manually. In fact; with one pilot exerting maximum effort; you could maybe get the manual strection about a quarter turn. All of this led us to believe that the Stabilizer was DEFINITELY jammed. Landed uneventfully; had equipment check us out then taxied to gate. Flight Attendants were given TEST brief and told there was no need to prepare for evacuation.


Second narrative: All systems checked ok at gate; but after rotation we discovered our electric stabilizer trim was inop. The aircraft was controllable; but required moderate yoke pressure.We got vectors over the water and stopped our climb at 12;000. We engaged the autopilot momentarily; but the Stab out of Trim light led us to complete that non-normal checklist.We used the Manual Trim Procedure; but felt the force required was excessive; and the trim wheel was not rotating freely.Dispatch contacted and priority handling requested. We completed the Jammed Flight Control and the Stab Trim Inop checklists; both which call for Flaps 15 landing.After again contacting Dispatch; Maintenance Control; and Flight Operations; we planned to divert back to ZZZ.We burned down to max landing weight and landed uneventfully.


Synopsis: B737 NG flight crew reported a jammed horizontal stabilizer trim system and elected to make an Air turn Back and precautionary landing.