Date: 201902
Local time of day: 0601-1200
Location: DEN.Airport, CO
Flight conditions: IMC
Weather elements / visibility: Cloudy; Icing; Snow; Turbulence; 1/4
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B DEN
ATC / advisory: TRACON D01
Aircraft component: Flap Control (Trailing & Leading Edge)
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Executed Go Around / Missed Approach; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was the pilot flying and we briefed for a ILS CATIII auto-land for Runway 35L. The weather was wind 030/12 1/4SM -SN OVC 200' -8 degrees altimeter 29.64. Just prior to DYMON the flaps were selected to 30 final setting. We were dispatched alternate go-around flaps 5 configuration. With the flap lever in the 30 detent; the gauge stopped between flaps 15 and 25 with a half a needle split. I elected to abandon the approach and fly a missed approach; which eventually put us on top of the cloud layer and out of icing at 10;000 feet. Once we were established above the cloud deck we split the flight deck and I continued to fly and talk on the radios and my First Officer ran the checklist. There is a condition note at the top that refers to the needle split on the indicator. We discussed the difference between the two and continued. We had a 1/2 needle split with the flaps and proceeded with the FLAPS - TRAILING EDGE FLAP DISAGREE checklist. During the running of the checklist it was determined that DEN was no longer an option with the visibility down to 1/8 mile.I [advised ATC] and stated we wanted to go to our alternate ZZZ where the weather was VFR. We had 12.1 fuel. Dispatch was notified of our [situation] via ACARS. Flight attendants and passengers were informed of our situation and the diversion plan. With the flaps stuck where they were; we flew at 170 knots for the rest of the flight and this was our final speed due to the winds in ZZZ. The checklist was completed and landing performance data was confirmed using the QRH. Enroute to ZZZ the flap indicator showed no needle split anymore but they were still stuck in between 15 and 25. On approach into ZZZ we encountered moderate chop and gusty winds. We landed in ZZZ and waited for the station to clear a jetway for us. The passengers were given alternate transportation to DEN and we secured the aircraft after completing our conversation with Maintenance.


Second narrative: On approach into DEN; IMC; icing; auto-land. When flaps were selected from 15 to 30; the flaps stopped moving at approximately 25 with less than 1 needle width difference on the flap indicator. Go around was performed; Abnormal Flaps - Trailing Edge Flap Disagree checklist was completed and we diverted to our planned alternate of ZZZ. Flaps moved from 25 to 15 after landing. The flap handle had been set to 15 in flight per the Abnormal checklist.


Synopsis: B737 flight crew reported trailing edge flap malfunction during approach to landing.