B737 flight crew reported flaps could not be moved from their setting during final approach and the gauge was 'frozen'. Flight crew conducted a go-around and diversion and landed using alternate flap extension procedure.
Synopsis
B737 flight crew reported flaps could not be moved from their setting during final approach and the gauge was 'frozen'. Flight crew conducted a go-around and diversion and landed using alternate flap extension procedure.
Narrative
Before flying the RNAV X into ZZZZ; we were given direct to the IF during arrival. This clearance left us with a steep descent profile to meet the company FAF standards. We elected to deploy the speed brakes and flaps to the 5 degree setting to expedite the descent. Up reaching 1500 ft. and continuing to slow; we extended the flaps to 10 at 205 Kias. We had a tailwind and were in and out of clouds giving us a bumpy ride and preventing the aircraft from slowing. With the bumps; we hit 207 Kias at one point; and I suggested we retract the flaps to 5. I placed the lever up to five and we decided to extend the gear instead. Then the FO called for flaps 15 at approximately 195 kts. I moved the handle to 15 and then noticed the flap gauge was showing flaps at 2. The gauge was 'frozen'; in that no selected flap handle setting caused the flaps to move. We placed the lever at 2. The FO had begun a descent on the approach and she decided to perform a go-around. We received clearance to climb to 2;000 ft. and turn first to south and then west. We held a speed below max flap extension speed of 250; eventually settling on 225 KIAS. I believed that our situation would not allow us to safely land at ZZZZ because of the shorter runway length. A quick check in the FMS told us we were 300 NM from ZZZZ1. With our generous fuel load; we felt a diversion to ZZZZ1 was the best option. We coordinated for a climb to FL180; and set up a climb and cruise at 225 KIAS. After leveling off and proceeding on the clearance; we began the troubleshooting process using the QRC and FM (Flight Manual). We determined we had a flap disagreement situation. Running the QRC had us try moving the flaps to no avail. The checklist directed using the alternate flap extension procedure and hopefully getting to a final flap setting of 15. The non-normal landing distance table presented us with an estimated landing distance of 7400 ft. We flew the cleared arrival procedure for RWY XXR in ZZZZ1. On downwind; just prior to turning base to join the final; we started the alternate flap extension as we had discussed. We changed duties where I became the PF and my FO was PM. She performed the alternate extension. We finished all checklists and slowed the aircraft appropriately. I flew an uneventful ILS to a full stop landing. Our final calculated approach speed was 162 Kias; similar to flying a heavyweight ILS in gusty winds; an event we are very familiar with. After clearing the runway and taxiing to park; we began the process of debriefing all appropriate personnel; to include a Foreign Government representative.
Second reporter narrative
During approach into ZZZZ (RNAV (GNSS) Runway X); there were some cloud layer and tailwind that we were going through to get to our FAP altitude of 1500. As Pilot Flying; FO asked for flaps 1 and then 5 to slow down and descend. Entering more cloud layers; the speed was bumping 205 kts with flaps 10; after brief automation management decided to put up to flaps 5. After gear down was decided to slow down; Captain (PM) noticed flap indicator was 2 and would not extend or retract. Captain worried of the runway length. Altitude was approaching about 900 RA and FO mentioned might need to go around. Tower was notified of a go around; which we were given a heading and leveling of 2000 ft. FO took over both radio and flying while CA did the checklist and communication to dispatch and FAs. Captain suggested ZZZZ1 which had long runway and is a Maintenance base; and quickly imputed into the FMS for required distance. Decision was made to divert to ZZZZ1; no emergency declared but we asked to have emergency equipment standing by. Staying at 225 kts we climbed to FL 180 while following the QRH for flap disagreement checklist. PF and PM role was switched; and as a crew briefed and went over the process of alternate flaps procedure while preparing for ILS DME X Runway XXR from ZZZZZ STAR (XXR requested for longer runway). Flaps 15 with final speed of 162; Captain landed on runway safely. Hardstand XX was given after landing and taxied to ramp without emergency crews following. After parking; debriefed with Maintenance; Foreign federal aviation official (who asked us to fill a statement and took photos of FAA license and medical); Chief Pilot (talked to CA) and the ZZZZ1 airport official arranged and bused the passengers and crew to the terminal for a designated gate area.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.