Narrative:

We were on a STAR coming into den when we were given vector off of the STAR. We were then cleared to descend to 9;000 feet. As we approached the airport (approximately 15-20 miles out) ATC asked if we had the airport in sight. The captain was the non-flying pilot and he told ATC that we had the field in sight. We were then cleared for a visual approach to runway 35L. We were set up to intercept the localizer at approximately a 65 degree angle from the southeast. I checked the approach plate for the ILS RWY35L approach and saw that the FAF was at 7;000 feet. I dialed 7;000 feet into the altitude pre-select and started a shallow descent. We were approximately 11 miles from the airport and I had stopped the descent at 7;500 feet when ATC issued us an altitude alert and advised us the minimum vectoring altitude for that area was 8;000 feet. I had the airport and the ground in sight the entire time; however due to the bright lights on the runway and the dark area to the southeast of the runway I had the illusion that we were closer to the airport than we really were. I initiated a climb back to 8;000 feet and we intercepted the glide slope at 8;000 feet. We landed safely without further incident. The root cause of this incident was a momentary lack of situational awareness with my exact distance from the airport and further compounded by the fact that we were approaching the airport/localizer from a sharp angle that was in between two fixes. A contributing factor was the night time illusion or 'black hole effect'. Those factors led me to believe that the FAF altitude was the better choice rather than an altitude of a fix further out on the approach. To avoid this from occurring in the future I will pick the more conservative of the altitudes when intercepting a localizer between two fixes to ensure I never get too low on an approach. I also will include any potential night time illusions during my approach briefing to make the other pilot in the cockpit aware of the potential hazard. Also; if there is any doubt as to what a safe altitude for a particular area would be when not on an instrument approach; the MSA or the MVA should be used.

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Original NASA ASRS Text

Title: CRJ-200 First Officer reported he descended below MVA on a night visual to DEN; citing lack of situational awareness as a causal factor.

Narrative: We were on a STAR coming into DEN when we were given vector off of the STAR. We were then cleared to descend to 9;000 feet. As we approached the airport (approximately 15-20 miles out) ATC asked if we had the airport in sight. The Captain was the non-flying pilot and he told ATC that we had the field in sight. We were then cleared for a visual approach to Runway 35L. We were set up to intercept the localizer at approximately a 65 degree angle from the southeast. I checked the approach plate for the ILS RWY35L approach and saw that the FAF was at 7;000 feet. I dialed 7;000 feet into the altitude pre-select and started a shallow descent. We were approximately 11 miles from the airport and I had stopped the descent at 7;500 feet when ATC issued us an altitude alert and advised us the minimum vectoring altitude for that area was 8;000 feet. I had the airport and the ground in sight the entire time; however due to the bright lights on the runway and the dark area to the southeast of the runway I had the illusion that we were closer to the airport than we really were. I initiated a climb back to 8;000 feet and we intercepted the glide slope at 8;000 feet. We landed safely without further incident. The root cause of this incident was a momentary lack of situational awareness with my exact distance from the airport and further compounded by the fact that we were approaching the airport/localizer from a sharp angle that was in between two fixes. A contributing factor was the night time illusion or 'black hole effect'. Those factors led me to believe that the FAF altitude was the better choice rather than an altitude of a fix further out on the approach. To avoid this from occurring in the future I will pick the more conservative of the altitudes when intercepting a localizer between two fixes to ensure I never get too low on an approach. I also will include any potential night time illusions during my approach briefing to make the other pilot in the cockpit aware of the potential hazard. Also; if there is any doubt as to what a safe altitude for a particular area would be when not on an instrument approach; the MSA or the MVA should be used.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.