Date: 202109
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class C ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Pitot-Static System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness; Troubleshooting; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: It was the FO (First Officer)'s leg into ZZZ. He had briefed the ILS approach which was the landing runway on the ATIS. A flap 40 degree landing was planned. The weather was VFR at the field with a cloud base at roughly 4;000 ft. MSL. ATC had us on a left downwind and turned us on a 90 degree base to final for Runway XXR. The FO had a 2.0 mile ring around the FAF ZZZZZ in the box to be fully configured for landing by then. And to the best of my recollection we were fully configured by the FAF. Runway XXR was in sight and ATC cleared us for the visual approach which was backed up by the ILS XXR. As we turned on to final for the Runway XXR at ZZZ; an accelerated red airspeed zipper came up on the bottom of the speed tape. There was an 'airspeed low' aural warning. The FO pushed the power in immediately; a stick shaker was felt; and the red airspeed zipper came down for the top of the airspeed tape. The FO disengaged the autopilot. There was very narrow gap on the upper and lower red zippers on the airspeed tape and the FO flew between the narrow gap. The FO stated; 'I'm not sure what is going on'. The chain of events happened at a very accelerated pace. Then the aircraft accelerated and the red zippers opened up and I called out ' watch your speed'. I remember seeing the aircraft accelerate near 159-160 kts. and I saw the red zipper on the top of the airspeed tape at 162 kts. In recovery; the aircraft climbed approximately 200-300 ft. We had Runway XXR in sight and the FO was in good position to land. I asked the FO if he was good with landing or if he wanted to do a go-around. The FO elected to continue the approach. Considering what we had just experienced; I felt that was a good choice. The FO continued the visual approach flying on the ILS XXR glide slope and localizer. At 1;000 ft. the FO made the 'stable' call out. At 500 ft. I made the 'stable' call out. We experienced no more airspeed red zipper indications or aural warnings for the remainder of the approach. The FO had a good landing. Upon landing I saw that the speed brakes did not automatically deploy so I manually deployed them. I noted after clearing the runway that due to the distractions; I failed to finish the 'below the line' checklist which I later mentioned to the FO. After the flight the FO and I decided to call Maintenance Control to discuss what had happened to us. Maintenance Control notified me that our Aircraft X had a 'history' of unreliable airspeed and that the FO's pitot tube was changed out. The Maintenance Representative voiced concern that it may be that our aircraft had a much 'bigger' maintenance issue and he wanted to pressure test the pitot system before releasing the aircraft. I put the 'write-up' in the maintenance book. I notified the outbound crew of what had happened and that my understanding was that Maintenance was on the way. ZZZ Operations was notified as well.I agreed with the Maintenance Representative that Aircraft X possibly had a bigger Maintenance issue at hand. When I called out 'watch your speed' as the airspeed was approaching 160 kts.; the First Officer had the same indication and matched mine. I have never seen anything like this event ever. So it seems possible that the airspeed was correct but the red zippers were not correct. Due to the distractions on final approach; I did not complete the Before Landing 'below the line' checklist and this did not register until touchdown when I had to manually deploy the speed brakes.I did not complete the Before Landing 'below the line' checklist. A go-around could have possibly helped in this situation but I do feel now as I did then; that the safest thing to do was land the aircraft straight ahead.




Synopsis: Captain reported auto pilot disconnected and the Flight Crew received erroneous airspeed indication which complicated the approach. After landing the Captain reported failing to run the after landing checklist due to distractions.