Date: 202012
Local time of day: 1801-2400
Location: ZZZ.Tower, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness; Fatigue
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Detector: Automation Aircraft Terrain Warning; Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Overrode Automation
Contributing factors: Human Factors; Environment - Non Weather Related
Primary problem: Environment - Non Weather Related

Narrative: Cleared for visual approach to Runway XXL on modified downwind; at 3;000 feet. Maneuvered aircraft to arrive at ZZZZZ at 3;000 to intercept LOC/ Glideslope simultaneously. Thought I was going to be above glideslope at ZZZZZ; asked FO to set 2;000 feet acquired Localizer inside of ZZZZZ; still at flaps 3. Drove into glideslope; selected flaps full. Radio altimeter briefly showed 800 feet due to terrain variation. Broke SOP of being fully configured by 1;000 feet.I accepted a night visual approach after a 12 hour; three leg duty day. Fatigue was a contributor. Hurried visual; should have intercepted final at IAF vs. FAF. My currency was spotty due to reduced flying on reserve.Never accept short visual approaches at end of long duty day.


Second narrative: I was acting as PM. Approaching ZZZ at night from the SW with a high overcast layer above. ATC had us on a downwind leg for [Runway] XXL at 4;000. The autopilot and auto thrust were engaged. Approximately abeam the end of the runway; ATC asked us if we had the field in sight. The CA/PF says he does; so I reported the field in sight. ATC then cleared us for the visual XXL. The PF then set 3;000 in the FCU and I confirmed and referenced the plate showing the FAF ZZZZZ at 3000. I believe the PF went open descent to 3;000 from 4;000. The PF then began his base leg turn. The intercept angle initially looked like it was going to join the final just outside of the FAF. As we approached 3;000 the PF continued the turn in. He asked me to set 2;000 into the FCU and set 1;000 v/s down. I complied as it appeared to me that the PF was trying to intercept the course and I assumed he was going to join inside of ZZZZZ/FAF. He readjusted his intercept to join the final at ZZZZZ or just outside it. By that time I began to realize we were getting low on the profile. I still had visual contact with the runway. At approximately that time; the airplane leveled at 2000 just inside of ZZZZZ and ZZZ tower advised us of a low altitude alert and to check our altitude with the current altimeter setting. I replied with our call sign. We continued at 2;000 until intercepting the glideslope and landed safely. We were approaching the end of a long duty day and it was a non eventful and quiet flight; so fatigue was a possible factor. I am also familiar with operating into ZZZ; so I was a bit complacent; as well as being in VFR conditions and being able to see the runway. Having both pilots confirm and verify any further altitude changes in the FCU after the setting of the lowest charted altitudes for the approach used.


Synopsis: Air carrier flight crew reported an unstablized approach and cited fatigue; time pressure and reduced flying as contributing factors.