Air Carrier flight crew reported ATC issued a low altitude alert when the crew descended below the charted altitude for an approach segment. Flight crew climbed back to correct altitude and continued approach.
Synopsis
Air Carrier flight crew reported ATC issued a low altitude alert when the crew descended below the charted altitude for an approach segment. Flight crew climbed back to correct altitude and continued approach.
Narrative
A visual approach with an RNAV backup to Runway XX was planned on a clear evening at ZZZ. On the leg from ZZZZZ to ZZZ; ATC assigned 9000 MSL as we approached the airport and asked if we had the runway in sight. We did not see the runway until too close for a safe visual approach so we requested vectors for an RNAV (GPS) RWY XX to help with our visual. Last minute vectors direct ZZZZZ1 and clearance for the approach was given by ATC at 9000 MSL. Inside ZZZZZ1 I realized VNAV was not engaged. At that point; and due to the high workload trying to get VNAV to reengage; I decided it was safe to continue and elected to fly the visual approach but neglected to immediately inform ATC. As we made the turn to final and abeam ZZZZZ2; ATC called to inform us that our altitude was low for that segment of the approach (approximately 8000 MSL abeam ZZZZZ2). We immediately; corrected our altitude; told ATC that we had the airport in sight and requested a visual which was approved just prior to ZZZZZ3. Visual approach was continued to an uneventful landing. Safety and terrain separation were never compromised.
Second reporter narrative
Crew was direct to ZZZ for an expected visual approach; backed up with RNAV for RWY XX. Assigned 9;000 from ZZZZZ to ZZZ; we did not see the runway until too close for a safe and stable visual approach; so we requested vectors for the RNAV XX. Upon request; we were vectored and then cleared direct to ZZZZZ1; 'cross ZZZZZ1 at or above 8;500; cleared for the approach.' Published altitude at ZZZZZ1 is 9;900. In order to engage VNAV; crew needed to recruise VNAV/remove published altitude at ZZZZZ1. PM went heads down to try to accomplish this; and mistakenly set FAF altitude in MCP (Mode Control Panel) window when directed; despite VNAV not being armed. Waypoints sequenced from ZZZZZ1 to ZZZZZ2 (8;500 restriction); with MCP alt set at 6;900 (FAF altitude). Both pilots became distracted by the task of getting VNAV to recruise/engage. Both pilots recognized the error as ATC called to inform us we were low for that segment of the approach. Aircraft had descended to approximately 8;050 feet as it approached ZZZZZ2. PF disengaged autopilot and initiated a climb to 8;500 and informed approach we had the airport in sight and were proceeding visually. Crew was VMC the entire time. Terrain clearance was maintained visually throughout the entire approach; and the flight landed uneventfully.
More incidents for this aircraft family →
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.