B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 14000
Distraction; Human-Machine Interface; Troubleshooting; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Executed Go Around / Missed Approach; Flight Crew FLC complied w / Automation / Advisory
Aircraft; Human Factors; Procedure
While on final to Runway XXL and descending toward 1;500 [feet] I called 'gear down; flaps 15; landing checklist.' Both my First Officer and I heard a momentary gear warning horn. Looking at the gear lights we noticed three red gear lights along with the normal three green lights. Looking at the overhead paned we saw three green lights. We both commented that the gear was down and safe. We continued the approach considering that maybe the lights may go out with further configuration changes. The lights remained on and at 500 feet AGL we got a 'too low gear' audio warning. I called for a missed approach. The red lights went out with the gear retraction. We ran the 'Gear Disagree' checklist. Since the lights were out at that time I elected to leave the GPWS circuit breaker; the final item on the checklist; in. We planned that during the next approach we would extend the gear early and if the same lights illuminated we would be able to finish the final item; if necessary; for a safe landing. We returned for another approach; the red lights never came on and the approach and landing were normal and eventful.
After a B737 landing gear was selected down both GREEN and RED indicator lights were ON and when TOO LOW GEAR warning sounded at 500 feet a go-around was executed. Upon returning for a second approach all indications were normal.