Widebody; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
Human Factors
On final to Runway 28R into SFO we received a low altitude alert from tower. We were approximately 400 feet below the VNAV path. As Pilot Monitoring (PM); I had been distracted by another Aircraft on final for 28L. The Captain (CA) had been concerned about being too high and fast on the FMS bridge visual and I believe through accident use of FLCH and speed intervene; he commanded the Aircraft to go too low (and I failed to monitor the situation properly. I perceived we were low; but thought it was part of his plan; until we received the alert from ATC (about 3 miles out at around 600').
Air carrier flight crew reported receiving a 'low altitude alert' from tower on VNAV approach into SFO.