Date: 201906
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Landing
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Flap/Slat Indication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Time Pressure; Human-Machine Interface
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Detector: Automation Aircraft Other Automation
When detected: In-flight
Result: Flight Crew FLC Overrode Automation
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Crew was on downwind for visual approach XXR at ZZZ. First Officer was high minimums with approximately 45 hours in the 737. Due to this; CA (Captain) was required to conduct the landing. A thorough brief and discussion took place at cruise and it was decided FO (First Officer) would fly the approach and when Before Landing Checklist was complete and aircraft was stable aircraft control would be exchanged for CA to complete the landing. ATC gave a base vector and traffic call for aircraft going to XXL. Crew visually acquired traffic and was told to maintain visual separation and were subsequently cleared for the visual approach. FO disengaged the autopilot and began calling for configuration changes. At approximately 2000 ft AGL the aircraft was configured with gear down and flaps 15 at 180 KIAS. Around this time TCAS produced a TRAFFIC TRAFFIC call based on the previously acquired traffic going to XXL. The alert momentarily caused a distraction to both pilots. The FO continued slowing the aircraft and at around 170 KIAS called for flaps 30 and the landing checklist. Aircraft speed continued to slow and approach target speed of approximately 154 KIAS. At no time after flaps were moved to 30 was aircraft speed increased above 170 KIAS and definitely did not approach flaps 30 over speed of 175 KIAS. The landing checklist was accomplished and the FO observed the CA moving the flap handle to the 30 position. However; due to flying the visual approach and being distracted by parallel traffic the FO did not crosscheck and verify the flap gauge was reading 30. The CA called 'flaps 30 green light' and visually saw flap gauge indicating 30. Shortly after this the 1000 ft call was made by the CA and controls were exchanged as previously briefed during the arrival briefing. The FO made a 500 foot call and CA replied with stable. At approximately 150 AGL the GPWS began issuing a TOO LOW FLAPS aural warning. Both FO and CA confirmed the flap handle was in the 30 position and that LE EXT green light was illuminated. The aircraft was stable on glide slope; lateral course; and airspeed. Around 100 to 50 AGL it was finally discovered that the flap gauge was reading 25 and not 30. By the time this configuration was verified by both pilots the CA had already begun the landing flare and aircraft was about to touchdown. Due to confusion; workload management and the extremely low altitude of the aircraft the crew determined the best course of action was to continue the landing. Upon touchdown the speed brakes auto deployed; auto brakes engaged and the aural warning silenced. After clearing the runway the flap handle was moved out of the 30 detent to up and the flaps properly tracked. The flap handle was then moved to the 30 detent and flaps properly tracked. Flap handle was finally moved up again and after landing low was completed. Crew taxied to gate and shutdown aircraft normally.


Second narrative: We were flying second leg of four day trip. Visual approach at ZZZ for runway XXR. My flying partner is under [minimum] hours so I needed to make the landing at ZZZ. On account of the excellent weather conditions I felt it safe and appropriate to let the First Officer fly the approach until we completed the landing checklist. We were executing a flaps 30 landing. Approximately 1600 ft the first officer called 'flaps 30; landing checklist'. I selected flaps 30; and completed the landing checklist noting the flap indicator at 30 and green light. At that point we transferred control of the aircraft and I completed the visual approach to XXR. The 1000 ft and 500 ft calls were all normal. After passing approach lights; and approximately 100 ft AGL we received a too low flaps GPWS warning. My thought was this must be a false warning. If the flaps weren't at the 30 position we would have received this warning at a much higher altitude (~500 ft RA) and of course executed a missed approach. This GPWS warning occurred so late; and the approach speed; pitch attitude; and aircraft feel were all normal I decided it was safer to continue the landing. The touchdown was normal. We exited runway XXR at [taxiway] intersection and held short of XXL as instructed. We noticed the flap lever in the 30 detent. The flap indicator was showing 25. As we had a few minutes to hold we retracted the flaps. Then selected 5; 15; and 30 positions all working normal. I am not certain why the flaps were in the 25 position. I must have not seen that the flap indicator wasn't 30; but 25 on completion of the landing checklist. If there was any indication of an unsafe landing condition I would have most certainly executed the missed approach as required for this particular GPWS warning. I felt it safer to continue the landing as we were basically in the flare phase by this point. I also felt that this was a false GPWS warning at that low an altitude on approach.


Synopsis: B737 flight crew reported a too low flaps GPWS warning at 100 ft AGL.