B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Situational Awareness
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Unstabilized Approach
Air Traffic Control Provided Assistance; Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Human Factors
I was pilot monitoring on this flight. ATC was giving us vectors for a visual approach to RWY XX at ZZZ. We were at 2;000 feet on a right base between waypoints ZZZZZ and ZZZZZ1 (1;500 feet MSL) when we told Approach we had the airport in sight. We were cleared for the visual and told to contact Tower. I said 'glide slope alive' and the First Officer asked for gear down flaps 15. I looked down to select the Tower frequency (which I didn't have preselected) and told them we were on the visual for RWY XX. We were cleared to land. When I saw we were capturing the localizer I noticed that the glide slope was now full scale deflection (low). The First Officer had selected a lower altitude (1;100 feet) on the MCP without telling me and so we were below the final approach fix altitude of 1;500 feet at ZZZZZ1. I called for a go around and we were vectored back around for a successful landing. The cause was a long flight across the country with last minute vectors to final for a visual approach led to the First Officer thinking we were high nearing the FAF and incorrectly setting an altitude lower than glideslope intercept altitude without verbally advising the Captain.
B-737-800 Captain reported an uneventful 'go around' due to a CFIT event during final approach.