B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Aircraft Equipment Problem Less Severe
Flight Crew Overcame Equipment Problem
Aircraft
On approach to landing at ZZZ we noted that the min airspeed band and stall band merged together showing an abnormal condition. We did a go around and determined that we had a slat problem (number 8 slat failed to extend). We eventually landed at flaps 15 per the abnormal checklist at ZZZ. We followed the checklist and procedures and made a successful landing.
On descent into ZZZ; while configuring; we had a[n] abnormal airspeed indications; amber overspeed and underspeed bands narrowed to within 2kts of one another at Flaps 15; and actually overlapped at Flaps 25. We went around; held; ran the 'LE FLAP TRANSIT' checklist; got appropriate landing numbers; and returned to land at ZZZ. We did a Flaps 15 landing per the checklist; and used max auto-brakes and max reversers until stopping distance was assured. Afterward; we learned from Maintenance that slat 8 was operating normally; but not indicating fully extended...which caused the abnormal airspeed indications. WX (Weather): VFR. It took us a while to diagnose the problem because the LE FLAPS TRANSIT light was not on at all flap settings...even when slats were extended but indicating improperly.
B737 Flight Crew encountered a slat problem during approach to land.