CRJ700 Pilots reported an EGPWS Terrain Warning while on final approach. The pilots stated their actions interrupted the autopilot's sequence and caused the aircraft to descend below the glide slope.
Synopsis
CRJ700 Pilots reported an EGPWS Terrain Warning while on final approach. The pilots stated their actions interrupted the autopilot's sequence and caused the aircraft to descend below the glide slope.
Narrative
While flying a night VMC approach to ZZZ we received a momentarily warning which was a result of mode confusion while tracking the ILS X approach to the airport. While descending on the intermediate segment; with 10300 ft. selected in the altitude pre-select; we switched modes to 'green needles' to track the ILS. Thinking that that the auto pilot had captured the 10300 ft. altitude; the Pilot Flying (PF) selected the missed approach altitude of 12000 ft. (above the current altitude). ALTS CAP had not occurred however; and the aircraft continued to descend below 10300 ft. As we identified that the aircraft was descending below the selected intermediate altitude; we received an EGPWS warning. The PF disconnected the auto pilot and added thrust to correct the flight path and reintercept glide path. Since the EGPWS warning was momentary; and correction put us fully configured and stabilized in VMC prior to a 4 mile final; we agreed to continue the approach. We landed without further incident. I usually have the approach chart up while on the approach but I had pulled up the balked landing and single engine missed approach chart and wasn't following the vertical profile on the chart; so I should keep following along with at the approach on the profile view of the approach chart. The approach lights were turned up to the highest level and I couldn't see the PAPI so lower; so I should lower the intensity once we have the runway in sight. Also ask the PF to verbally state what's going on with the auto pilot when I get a little behind that airplane.
Second reporter narrative
While flying a night VMC approach to ZZZ we received a momentarily EGPWS warning which was a result of mode confusion while tracking the ILS X approach to the airport. While descending on the intermediate segment; with 10300 ft. selected in the altitude pre-select; I switched modes to 'green needles' to track the ILS. Thinking that that the auto pilot had captured the 10300 ft. altitude; I selected the missed approach altitude of 12000 ft. (above the current altitude). ALTS CAP had not occurred however; and the aircraft continued to descend below 10300 ft. As I identified that the aircraft was descending below the selected intermediate altitude; we received an EGPWS warning. I disconnected the auto pilot and added thrust to correct the flight path and reintercept glide path. Since the EGPWS warning was momentary; and correction put us fully configured and stabilized in VMC prior to a 4 mile final; we agreed to continue the approach. We landed without further incident. Erroneously thinking that I had observed an ALTS CAP at 10300 ft. before I selected the missed approach altitude was the error that led to this altitude deviation. Additionally; this occurred while we were receiving updated winds from the Unicom operator which caused us to discuss and calculate our crosswind/tailwind component for landing. In the future I intend to verbalize ALTS CAP before selecting the next altitude. This should help my awareness and enhance the shared mental model as a flight crew.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.