B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 200
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types
Aircraft; Weather
We were on a visual approach tracking the localizer and glideslope for Runway XX at ZZZ. Winds were a little gusty but nothing out of the norm. Our REF (Reference) speed was 125 and TARGET 134. We were configured for landing flaps 30 and stable at 1000 ft. Airspeed was fluctuating slightly +3-5 minus 1-2 from our target speed. At around 700 ft AGL (Above Ground Level) we got an 'airspeed low' aural alert. Our airspeed was still around our TARGET airspeed. The low airspeed portion of the airspeed tape momentarily shot up past our TARGET speed and then came back down to normal range. The event lasted around a second. We both questioned what that was all about and decided to continue the approach as we were still stable on the profile with normal indications. I asked the FO (First Officer) to add five more knots to our TARGET speed; just out of caution. The approach continued normally until around 50 ft when we again got the Airspeed Low aural alert. We were around 135-140 KIAS (Knots Indicated Airspeed) at that point. Then; at Less then 10 ft; maybe around five feet in the flare; we had a momentary stick shaker activation. I'm not sure what the airspeed was at that point as I was in the flare and focused on the runway and landing. The shaker lasted for less than one second.Both of us were surprised at stick shaker activation and didn't know what caused it or the low speed alerts as the approach was stable and normal the whole way down. After clearing the runway I called for flaps up. The FO moved the flap handle and looked up at the overhead flap/slat annunciation lights and said the right outboard slat light was not illuminated. We taxied to the gate without incident. We had Maintenance come up and explained what had occurred during the approach. He went down and downloaded any errors. When he came back up he told us we had a slat malfunction that did not deploy. We had an unscheduled aircraft swap and continued with the remainder of our day without incident.We do not receive any caution indication of a slat that malfunction. I have been reading the FRM to see how that effects stall logic but have not come across any useful information. There also are no QRH (Quick Reference Handbook) procedures. Another issue I'm confused on is I believe the overhead light should have been amber and not 'un-lit' to indicate it wasn't in a commanded position. I did test it during pre flight and then again at the gate after the occurrence with a normal test indication. That overhead annunciation is now in my landing scan.
B737 flight crew reported a leading edge slat malfunction during approach and landing.