Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 180; Flight Crew Type 22000
Aircraft Equipment Problem Less Severe
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Aircraft
On initial climb out off of Runway XX ZZZ; we experienced the aircraft pitching up without the autopilot engaged at approximately 4500 feet. I tried using the down trim and it was not working; I immediately pushed forward on the yoke and manually trimmed the aircraft back into trim. We notified ATC we needed to level off at 6000 feet. We assessed the situation and ran the appropriate checklist. While doing this we advised ATC we needed to return to ZZZ and [coordinated with ATC]. We were vectored for a downwind leg for Runway 23. The approach was briefed; [performance data calculated] with non-normal and brake cooling checked; Dispatch notified and QRH Checklist completed. We made a flaps 15 landing with no further issues.
On initial climbout; passing approximately 4500' MSL; the Captain (as PF [Pilot Flying]) verbalized that the nose down trim was inoperative as the pitch attitude rose to 20 degrees NU (Nose Up). The PF began leveling the aircraft with nose down yoke and manual trim followed by the activating the stab trim cutout switches; leveling off at approximately 5500' MSL. As PM (Pilot Monitoring); I coordinated with ATC and requested a level off at 6000' MSL. As the PF leveled off at 6000' MSL and turned downwind; he told me that the nose up trim had been working; just not the nose down trim. We descended to VMC at 4000' MSL and ran the QRH Stab Trim INOP procedure to completion. We set up for the ILS XXR to ZZZ; selecting flaps 15 according to the QRH/checklist; and landed uneventfully. Emergency vehicles met us coming off the runway but no further assistance was required.
B737 flight crew reported nose down trim inoperative on initial climb out.