Date: 201902
Local time of day: 0601-1200
Location: SJC.Airport, CA
Flight conditions: IMC
Weather elements / visibility: Rain; Cloudy; Turbulence; Windshear
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class C SJC
ATC / advisory: TRACON NCT
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Communication Breakdown; Confusion
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach
Contributing factors: Weather; ATC Equipment / Nav Facility / Buildings; Procedure
Primary problem: Procedure

Narrative: We were flying to San Jose; CA. Prior to descent we briefed the approach to 12R which we anticipated starting on the ILS then to a visual approach. There was a lot of rain shower activity in the area and strong winds aloft. We anticipated some turbulence on the descent so I asked the flight attendants to secure the cabin and be seated shortly after top of descent. When we checked in with the final controller we were told they were switching runways to 30L. The FO (First Officer) was the flying pilot and I was the monitoring pilot. I loaded the new approach in the FMC (Flight Management Computer) and re-tuned the radios. We briefed the ILS and set the minimums but were still expecting a visual approach. Then we went through the triangles for the descent checklist. As we were being vectored we were assigned 200 knots and given a base leg turn. At this point the identifier for the ILS 12R (same frequency for both runways 12R and 30L) was being displayed. I asked the Controller about this and he said they were still landing planes on 12R and we would be number one for 30L. We were now on an intercept vector and were told to join the 30L LOC. I informed him the identifier was still showing the ILS for 12R so we would join the final using LNAV. He offered a heading of 305 and to maintain 3000 and to let him know if we got the airport in sight; so at this point we were still anticipating a visual approach. At this point we were still trying to comply with the speed but we would need to start slowing. We finally got an ident for ISJC and were about 14 miles out and were cleared for the approach. We were painting some weather on the radar but it did not appear threatening. Once we were cleared for the approach the FO armed the app mode and the flight guidance indicated the LOC and GS were captured. I set the missed app heading and MAP (Missed Approach) altitude. At this point there were significant fluctuations in the glide slope. The AP (Autopilot) was engaged so the airplane was pitching up and now chasing the fluctuations. I assumed the ILS protected area was not being protected as the weather was still reported VFR and suggested the FO hand fly. I also told Approach Control we were slowing and they assigned 180 knots to HIVAC. We had been put into a rushed spot but I felt we would could still get stabilized in time. As the FO was trying to slow and configure; the airplane was not slowing down as quickly as would expect. I was actively monitoring the flying and not sure if we were given a hand off to Tower or not but in any case when we crossed HIVAC I made the altitude cross checks call but was still on approach frequency. We were still getting configured and finally did so at about 1200 feet. We were running the landing checklist when I heard our call sign from approach. I quickly acknowledged and switched to tower. At this point we were still IMC experiencing moderate rain. I believe we were cleared to land but then Tower told us they were receiving a low altitude alert and gave us the altimeter setting. We had ours set correctly and we were just able to see some ground but not the runway. We appeared to be on the glide slope both by raw data and the airplane symbol on the flight directors. We were at 800 feet and the runway was not in sight and I couldn't figure out how we could be low but realized we needed to go around and announced 'go around'. The FO immediately initiated the go around and I announced it to the Tower. We followed the go around instructions and checked in with Departure. They asked us what the reason for the go around was and I told him we had a low altitude alert from the Tower and we were still IMC. He then said the airplane behind us on the approach experienced wind shear with a gain of airspeed of 50 knots and a 4000 fpm descent rate. The FO and I discussed alternates and our fuel state which was about 6500 lbs. I got weather for SJC. SJC weather had improved and the winds were benign so we elected to goback to SJC. We acquired the runway visually about 10 miles out and flew a visual approach to 30L. Even though we had briefed the ILS we were expecting a visual approach based on the latest ATIS. This allowed me to accept a rushed approach and attempt to comply with an assigned speed that was too fast for the conditions. There was also confusion about which ILS was being transmitted which rushed us even further and trying to comply with the clearance at the last minute.




Synopsis: Air Carrier Captain reported a go-around following a low atlitude alert in inclement weather.