Date: 202102
Local time of day: 0001-0600
Location: ZZZ.TRACON, US
Flight conditions: VMC
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ; Tower ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Situational Awareness; Confusion
Second reporter function: Pilot Flying; First Officer
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Unstabilized Approach
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: We were being vectored from the northwest to the ILS approach and descending to 2;000 ft. when Tower asked if we had the airport in sight. This was my first time in ZZZ and although I thought I saw the airport I was not in a hurry to call it in sight; just to be sure. I verbalized that with the First Officer but he had been there before and was comfortable calling the airport in sight; so I did. Our initial vector would have taken us just outside the Final Approach Fix. However; when Tower issued clearance for the Visual Approach; the First Officer turned to a heading that would take us inside the Final Approach Fix. At the same time; he continued to descend while configuring with flaps (I think at either 10 or 15) and landing gear; and the speed brake extended. As the descent continued; Tower issued an 'Altitude Alert' and instructed us to adjust immediately. I cannot remember the exact verbiage; but there was a mention of our altitude being 1;200 ft. and perhaps something about 'minimum vectoring altitude.' The First Officer immediately adjusted his attitude to level off at around 1;200 ft. and continued to fly towards the runway center line. We were approximately abeam the Final Approach Fix at this point. He then asked for more flaps; ultimately Flaps 30; for the landing. I realized at about that point that he still had the speed brake extended and told him. He immediately stowed the speed brake and intercepted the visual glide path to the runway. I think he asked me at about that point if I was okay to continue. He was on the glide path and stabilized; so I said 'yes.'On landing rollout I noticed what sounded like an open microphone on the Tower frequency. Since there didn't seem to be any other aircraft on the frequency; I suspected it was coming from our aircraft. The Tower made a broadcast to all stations on the frequency that they were broadcasting on an active ATC radio frequency; and that they should cease immediately. When I made the '80 kts.' call out on landing roll; I heard myself over the radio. That confirmed that the First Officer was holding down the microphone button in his grip on the yoke. As soon as he loosened his grip; the transmission stopped.


Second narrative: I was the pilot flying. Based on the weather reported we briefed the RNAV Arrival to be followed by the ILS Approach. We made special note that we were not to utilize the Autothrottle for the approach due to MEL(Minimum Equipment List) restriction. The arrival went as planned until we were given a vector off the arrival and then direct to the Final Approach Fix and a descent to 2;000 ft. As we were a bit high and fast; the speed brake was being utilized to expedite descent. While proceeding to the Final Approach Fix; the weather was acceptable to proceed visually so we reported field in sight and were cleared for the Visual Approach. Due to the high intercept angle to the Final Approach Fix I turned to establish a more acceptable intercept angle to capture the localizer. My perception looking outside was that we were quite high so asked the Pilot Monitoring to set Touchdown Zone Elevation. I failed to engage Vertical Nav for better situational awareness in relation to my vertical path and relied solely on the visual sight picture until on final. While on a dogleg to final we received an ATC Altitude warning alert telling us that we were below the sector altitude. We were approximately 1;100 ft. just abeam of the Final Approach Fix on a dogleg to final. I then stopped the descent until approaching final approach course and engaging Approach mode for glideslope capture. Continued the Visual Approach to a landing.


Synopsis: B737 Flight Crew reported after being cleared for a Visual Approach the Pilot Flying turned toward the airport inside the Final Approach Fix and received a low altitude alert from ATC.