B737 Next Generation Undifferentiated
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Situational Awareness; Training / Qualification
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Unstabilized Approach
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Human Factors; Procedure
On arrival to DFW; we were in the descent on radar vectors to a visual for Runway 17R. We were cleared to fly direct to YALTA intersection depicted on ILS 17R approach. I don't remember when we were cleared to continue descent to 3;000; but I did realize that I would cross it higher than 3;000 feet and was indicating 250 knots. With the speedbrakes fully deployed; my descent projection (green banana) showed that I would reach 3;000 feet right over YALTA. Still; my speed would be at 250 knots being that the aircraft was not slowing yet. A few miles prior to YALTA we called the field in sight and were cleared for the visual. Somewhere prior to YALTA I called gear down and started to slow down. I don't remember where I was when I spun the altitude alert on the MCP to a lower altitude than the next fix; the final approach fix BBAKR; but it was prior to it. I did this to prevent the aircraft from leveling off at 2;200 beyond BBAKR to avoid an unstable approach. Little did I know that not only did I catch up with the glidepath; but I actually was below the glidepath. Somewhere around BBAKR the Tower advised us of a low altitude alert. I had already recognized it and leveled off to intercept the PAPI. The aircraft began to descend one more time and then I disconnected all automation and maintained level flight until I intercepted the glidepath. The runway was in sight at all times during the approach and the visibility was greater than 10 miles. Two times we had an aural alert: 'glideslope; glideslope.' However; it did not happen until inside BBAKR which also was the time when the Tower advised us of the low level alert. There were no deviations in airspeed and the landing was normal. It was [very early morning] and without any doubt fatigue was a contributing factor. This is probably why I missed when the aircraft caught up with the glidepath and descended below it. My First Officer also felt fatigued. We were both called out on short notice to fly this flight.Two things I have learned from this event: Don't just focus on the runway in front of you; and brief for all visual approaches that even though it is a visual approach; I do not intend to cross lower than the FAF altitude until reaching it. If I do; call it out. It is easy to take things for granted when conducting visual approaches. I will not allow that to happen again. I really wish the call out for FAF altitude on the 737 was never removed. I now see how even more beneficial it is to have this call out. However; in my opinion; this call out should be made by the pilot monitoring and not the Captain at all times. It is my understanding that this was not removed from our other fleets. Where is standardization in this instance?
A B737NG Captain; high and fast approaching localizer intercept and the FAF on a visual approach; descended below the glideslope and triggered a Low Altitude Alert from the Tower.