Narrative:

I was capt/PF (pilot flying) during night; VMC descent to 16R krno. After being cleared for visual approach; I set 7400 in MCP altitude window to match glide slope intercept altitude. On left base; the autopilot was on; flaps 20; and speed 170. Approaching 7400; I set threshold elevation to stay on glide path; intending to select the approach switch once turned into final. However; I never selected VNAV; and was still in flch when I selected the lower altitude. As we turned onto final; I noticed we were below path. I realized my mistake and started leveling off as we got a GPWS terrain warning. The pm (pilot monitoring) knew I intended to lavs to final; but did not notice I failed to select VNAV. After the terrain escape; we were still far enough out to recapture the proper glide path. From that point on; the approach and landing were uneventful.lessons learned: I have been on this airplane for several years and never made such a critical/obvious mistake. If I had verbalized lavs on base leg; I would not have missed the VNAV step; and the pm would have been more cued into what I was doing with the airplane. Also; I had the HUD down but [enhanced vision system] was off. In the future; I'll use evs in areas of high terrain for better visual cues. Most importantly; I am reminded that mistakes can happen any time. Special qual airports are designated for a reason - attention to detail is essential; especially in vertical phases of flight within the terminal area.

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Original NASA ASRS Text

Title: Air Carrier Captain reported receiving a terrain warning on short final into Reno due to inattention to automation.

Narrative: I was Capt/PF (Pilot Flying) during night; VMC descent to 16R KRNO. After being cleared for visual approach; I set 7400 in MCP altitude window to match glide slope intercept altitude. On left base; the autopilot was on; flaps 20; and speed 170. Approaching 7400; I set threshold elevation to stay on glide path; intending to select the approach switch once turned into final. However; I never selected VNAV; and was still in FLCH when I selected the lower altitude. As we turned onto final; I noticed we were below path. I realized my mistake and started leveling off as we got a GPWS terrain warning. The PM (Pilot Monitoring) knew I intended to LAVS to final; but did not notice I failed to select VNAV. After the terrain escape; we were still far enough out to recapture the proper glide path. From that point on; the approach and landing were uneventful.Lessons learned: I have been on this airplane for several years and never made such a critical/obvious mistake. If I had verbalized LAVS on base leg; I would not have missed the VNAV step; and the PM would have been more cued into what I was doing with the airplane. Also; I had the HUD down but [Enhanced Vision System] was off. In the future; I'll use EVS in areas of high terrain for better visual cues. Most importantly; I am reminded that mistakes can happen any time. Special qual airports are designated for a reason - attention to detail is essential; especially in vertical phases of flight within the terminal area.

Data retrieved from NASA's ASRS site 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.