Narrative:

While being vectored for the approach we began our final configuration for landing. Approaching the outer marker in a shallow descent passing 2000 ft MSL I commanded for the flaps to be set at 30 degrees and we began the before landing checklist. The first officer (first officer); who was the pm (pilot monitoring); read flaps; and I responded 'flaps;' as I looked over at the flap gauge. We both verified on the flap gauge that the left flap was indicating 30 degree; while the right flap was still at the 25 degree indication. There was no indication of uncommanded roll; or yaw of the aircraft. We immediately decided to discontinue the approach and requested vectors or a holding pattern so we could run a checklist. We were cleared initially to 1500 ft MSL; and then up to 4000 ft. Climbing through approximately 1200 ft MSL; I reengaged the autopilot to get an additional level of automation working for me; so I could concentrate on the situation at hand. We pulled out the QRH; and ran the trailing edge flap asymmetry checklist from the QRH. We completed the QRH checklist and ran landing performance numbers for landing with flaps set at 15 degree. At this point the aircraft was taken care of; so it was time to notify the company; the F/as (flight attendants) and the passengers. The pilot monitoring took care of these duties while I; as the PF (pilot flying); maintained radio communications with air traffic control; and flew the aircraft. After all external notifications were done and checklists were complete; we requested vectors back to the approach course for landing. The approach and landing were uneventful; and we arrived with maintenance waiting for us at the gate. I contacted dispatch; and the chief pilot on duty; by telephone; and spoke with maintenance personnel while my first officer briefed the crew that was to take the aircraft. The aircraft was subsequently taken out of service for maintenance; and my first officer and I proceeded to another gate and pressed on with our day.by using automation to lighten our workload; dividing up tasks and working together as a team to diagnose and address a mechanical situation; using the appropriate checklists; and letting other members of the company team know what was going on; an abnormal situation was handled in a methodical and professional manner by everyone involved.

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Original NASA ASRS Text

Title: B737 flight crew reported a split flap indication (25 and 30 degrees) with no rolling tendency and no flap asymmetry indication. A go-around was initiated and the flap lever was moved to 15 and the flaps both moved to 15. QRH procedures were accomplished and a flaps 15 landing ensued.

Narrative: While being vectored for the approach we began our final configuration for landing. Approaching the outer marker in a shallow descent passing 2000 ft MSL I commanded for the flaps to be set at 30 degrees and we began the Before Landing Checklist. The F/O (First Officer); who was the PM (Pilot Monitoring); read flaps; and I responded 'flaps;' as I looked over at the flap gauge. We both verified on the flap gauge that the left flap was indicating 30 degree; while the right flap was still at the 25 degree indication. There was no indication of uncommanded roll; or yaw of the aircraft. We immediately decided to discontinue the approach and requested vectors or a holding pattern so we could run a checklist. We were cleared initially to 1500 ft MSL; and then up to 4000 ft. Climbing through approximately 1200 ft MSL; I reengaged the autopilot to get an additional level of automation working for me; so I could concentrate on the situation at hand. We pulled out the QRH; and ran the Trailing Edge Flap Asymmetry Checklist from the QRH. We completed the QRH Checklist and ran landing performance numbers for landing with flaps set at 15 degree. At this point the aircraft was taken care of; so it was time to notify the Company; the F/As (Flight Attendants) and the Passengers. The Pilot monitoring took care of these duties while I; as the PF (Pilot Flying); maintained radio communications with Air Traffic Control; and flew the aircraft. After all external notifications were done and checklists were complete; we requested vectors back to the approach course for landing. The approach and landing were uneventful; and we arrived with Maintenance waiting for us at the gate. I contacted Dispatch; and the Chief Pilot on Duty; by telephone; and spoke with Maintenance Personnel while my F/O briefed the Crew that was to take the aircraft. The aircraft was subsequently taken out of service for Maintenance; and my F/O and I proceeded to another gate and pressed on with our day.By using automation to lighten our workload; dividing up tasks and working together as a team to diagnose and address a mechanical situation; using the appropriate checklists; and letting other members of the Company Team know what was going on; an abnormal situation was handled in a methodical and professional manner by everyone involved.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.