Air carrier flight crew reported receiving a low altitude alert from ATC that resulted from the crew responding to a TCAS RA during approach into SFO.
Synopsis
Air carrier flight crew reported receiving a low altitude alert from ATC that resulted from the crew responding to a TCAS RA during approach into SFO.
Narrative
Weather was VFR.I was the Pilot Monitoring.SERFR4 arrival.Told to expect TIPP TOE Visual 28L.Roughly after EPIC on the arrival ATC started vectoring us….heading/altitude/airspeed commands from ATC.We never did get back on arrival.Around SIDBY/CHERA on the approach; ATC started calling out 2 different traffic targets.We were looking for them while still being vectored. High workload for both pilots; heading changes; airspeed changes; altitude changes.ATC asked us to call airport or traffic in sight.Before we could respond with anything in sight ATC told us to intercept the localizer for 28L Cleared for the approach contact tower.We were slightly high. As we got back on glideslope we saw the traffic that was to land 28R. It was Aircraft Y above us; and just behind us. Aircraft Y caught up to us.At about 1200 feet we received TA that immediately went to an RA. The automation told us to descend. As we were performing the descend maneuver Aircraft Y kept coming down on its glide path. We had a visual with Aircraft Y the whole time.ATC called low altitude alert and we responded to them we were responding to an RA.ATC asked for our intentions. The RA went away by 500 feet. At that point we were stable and on glidepath. Told ATC we were landing. We were in kind of a bad position with this RA. Aircraft Y just kept descending down.
Second reporter narrative
I was PF flying the approach with autopilot off. We were on the tip toe visual 28L and cleared to land. Around 1200-1500 ft we received a TCAS RA as there was an Aircraft Y on final for 28R abeam our position at a slightly higher altitude. The descend command was followed and resolved eventually. We had no option but to descend. We leveled off around 600 feet and intercepted glide slope again. Stable by 500 and continued the landing eventfully. We did receive a low altitude alert from ATC as we had responded to the RA.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.