2025-01 · NASA ASRS report 2201477
Air carrier flight crew reported descent below glidepath on initial approach due to incorrect altimeter setting resulted in a Ground Proximity Warning.
Expecting ZZZ RNAV-Z XX. ZZZ center issues descend via the ZZZZZ arrival; ZZZ1 altimeter 29.95." Altimeter at ZZZ is advertised as 29.79 on the ATIS. We were aware that there was a big difference between ZZZ1 alt. and ZZZ; assumption was that ZZZ appr and/or final controller would issue the latest alt. setting upon check-in seeing as how we were cleared to descent via so far out from ZZZ; practically abeam ZZZ1. Boy was I wrong. While being vectored to join an approximately 10nm straight in final; cleared for the visual for XX using the RNAV-Z XX as backup; me and the FO both noticed that we seemed a bit low when capturing the GP at 2000ft; with 4 red showing on the PAPI. We heard no other aircraft in front of us ask about the alt setting. I made a quick comment to the First Officer confirm the ATIS alt setting of 29.95; to which he confirmed. The next events literally happened within seconds. I had already disconnected the AP outside the FAF and was hand flying the approach when I keyed the mic to query ATC of the local alt. setting; to which they replied "29.75!" At this point I was already in the process of adjusting our pitch to get us back on the PAPI while simultaneously adjusting and correcting the alt setting on the guidance panel. As soon as I started to correct the ALT setting; and already showing 3 red 1 white on the PAPI per my alt correction; we momentarily got and EGPWS caution alert for an obstacle in front of us (buildings on the extended CL of rwy XX). Before I even had time to process what was going on; get my hands back on the TL's and react to the alert for the escape maneuver; the EGPWS alert went away. Slightly confused on what just happened and angry with ATC for not advising of the proper local alt.; as well as not having the EGPWS alert active while already reestablished back on the PAPI/GP; stable; in visual conditions; with no threat to the aircraft we continued on the approach to a safe landing.Suggestions: With regards to RNAV-RNP as well as PBN with actions and callouts; we are taught to ensure that local alt is set and confirmed (cross checked) when at IAF. Again it is emphasized more on the RNP and PBN approach setup but it applies equally to any Baro VNAV GP like the RNAV-Z XX. With ZZZ appr never giving us the latest local altimeter setting when we check in on our last leg; nearly midnight and wrestling with 30kt plus gusts; we forgot to check and change the altimeter to latest ATIS setting and/or ask approach for the latest which basically led to a breakdown in comms between us and ATC; however given that the responsibility lies with us; the flight crew; even if there were an emphasis to x-check alt setting for an RNAV such as this one the incident probably would have still occurred since we were flying on what we thought was the most current alt setting that was given while on the ZZZ arrival."
Expecting ZZZ RNAV-Z XX. ZZZ center issues descend via the ZZZZZ arrival; ZZZ1 altimeter 29.95." Altimeter at ZZZ is advertised as 29.79 on the ATIS. We were aware that there was a big difference between ZZZ1 alt. and ZZZ; assumption was that ZZZ appr and/or final controller would issue the latest alt. setting upon check-in seeing as how we were cleared to descent via so far out from ZZZ; practically abeam ZZZ1. While being vectored to join an approximately 10nm straight in final; cleared for the visual for XX using the RNAV-Z XX as backup; CA and I both noticed that we seemed a bit low when capturing the GP at 2000ft; with 4 red showing on the PAPI. The Captain made a quick comment to me to confirmed the ATC issued alt setting of 29.95; to which I confirmed. As we were coming down we still seemed much lower than we should have. The Captain had already disconnected the AP to hand-fly the last bit of the approach. He inquired about the current altimeter setting; to which ATC replied with 29.75. Which is a big difference than the 29.95 we had originally been given. The Captain then started to pitch up to correct both the visual glide path; and corrected his altimeter settings; as did I. In the exact moment of fixing altimeter settings; we momentarily got and EGPWS caution alert for an obstacle in front of us (buildings on the extended CL of rwy XX). Before he could even react; the EGPWS alert went away. After the 3 second event; we were already back on glide path in visual conditions! We continued the approach to landing."
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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