Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Situational Awareness; Distraction; Communication Breakdown
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew FLC complied w / Automation / Advisory
Human Factors
Cleared direct to ZZZZZ which is a fix on the RNAV XX with clearance to turn to 180 heading after crossing ZZZZZ. Descent issued by Approach to 2;500 feet which crew acknowledged. The 180 heading was preset on the heading bug by PM (Pilot Monitoring). Night conditions prevailed and airport was not yet in sight; however; I was beginning to pick up airport beacon. As we approached ZZZZZ; while still in descent; I began making out the Runway (XXR). As PF (Pilot Flying)/PM were visually confirming; the aircraft began a smart turn to the inbound course of the RNAV approach. This momentary startle effect caused me to reach up and select HDG mode. The only thing I can think of is that I must have bumped the alt select knob and lowered it; as CDFA minimums of 1;250 feet got posted on the AAD (Automatic Activation Device). As PF/PM agreed runway was in sight and before we could inform Approach; the aircraft had passed through 2;500 feet and we received a low alt alert from Approach. I immediately disconnected autopilot and stopped descent. Approach verified we had the field in sight; which we confirmed; and then were cleared for the visual. I began the descent again and maintained profile till landing. At no time were any [Ground Proximity Warning System] warnings encountered; and aircraft was configured and stable by all SOPs.I cannot confirm that I reset the AAD device; however; it must have been bumped or turned initially when the smart turn began; because as I stated prior; the smart turn caught me off guard as we both were looking outside acquiring the runway visually. This was a beautiful night with VMC conditions; however the placement of the runway in surrounding lights and the fact that the Initial Fix and Final Approach Fix legs are doglegs complicated visual orientation. I should have just asked for the approach off of ZZZZZ.
Citation 680 Captain reported receiving a low altitude alert from ATC on a night visual approach.