Narrative:

Weather in albany was forecast to have light snow during the arrival timeframe. We (captain and first officer) had continued to monitor the local alb weather via ACARS and wsi throughout the flight. At the XA00 ATIS; the altimeter was 30.08 and the nearby snow was mostly west and north of the airport (wsi radar). At the XB00 Z ATIS; the altimeter was 30.01; and the snow was still staying off the airport in roughly the same areas. Our scheduled arrival was XB50 Z; but we were showing arriving about 15-20 early. We checked in with albany approach control with the XB00 Z weather. I do not know if approach provided the local altimeter; but I do know that we had 30.01 set; based on ATIS; and we did not change. We descended below some clouds and could see the airport from more than 10 miles. We had originally planned to fly the ILS 19 and had briefed the approach in case the snow arrived and IMC conditions became a factor. Approach asked us if we wanted the RNAV Z approach to runway 19. We said that would be fine. We loaded the FMS with the RNAV Z 19 and briefed the points/altitudes; even though we had VMC. We were cleared to tukuy (if) and we flew the approach as published with the autopilot engaged. As we rounded the corner between cugop and wisig; I commented that we were low (could see the PAPI; it showed 1 white/3 red). At about wisig; I commented to the other pilot that the HUD was showing us low and touching down prior to the runway; but that I would not let that happen (we were in IMC mode on the HUD with a -3.00 glideslope angle and the tdze set in the altitude). I left the autopilot engaged to see if the automation was going to correct the low situation. I crosschecked the instruments and the lateral and vertical navigation pointers were centered in the middle. As the white PAPI started to change color to red; I disconnected the autopilot and corrected the aircraft flight path back to 2 white/2 red on the PAPI. The vertical guidance (gp) indicator for the RNAV on the instruments then showed us high when the PAPI showed us on the proper glide path. I do not remember seeing the ILS indication during the event. I feel confident that we both had the ILS localizer frequency and course set; but I did not look for the glideslope during the event. The landing was uneventful. After arrival at the gate; I asked ground control 'what was the altimeter indicating'; and they said '29.94 and falling rapidly.' I estimate this altimeter was provided at XB35 Z.

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Original NASA ASRS Text

Title: Air carrier flight crew reported being too low while flying an RNAV approach because of a rapidly decreasing atmospheric pressure in the area.

Narrative: Weather in Albany was forecast to have light snow during the arrival timeframe. We (Captain and F/O) had continued to monitor the local ALB weather via ACARS and WSI throughout the flight. At the XA00 ATIS; the altimeter was 30.08 and the nearby snow was mostly west and north of the airport (WSI radar). At the XB00 Z ATIS; the altimeter was 30.01; and the snow was still staying off the airport in roughly the same areas. Our scheduled arrival was XB50 Z; but we were showing arriving about 15-20 early. We checked in with Albany Approach Control with the XB00 Z weather. I do not know if Approach provided the local altimeter; but I do know that we had 30.01 set; based on ATIS; and we did not change. We descended below some clouds and could see the airport from more than 10 miles. We had originally planned to fly the ILS 19 and had briefed the approach in case the snow arrived and IMC conditions became a factor. Approach asked us if we wanted the RNAV Z Approach to Runway 19. We said that would be fine. We loaded the FMS with the RNAV Z 19 and briefed the points/altitudes; even though we had VMC. We were cleared to TUKUY (IF) and we flew the approach as published with the autopilot engaged. As we rounded the corner between CUGOP and WISIG; I commented that we were low (could see the PAPI; it showed 1 white/3 red). At about WISIG; I commented to the other Pilot that the HUD was showing us low and touching down prior to the runway; but that I would not let that happen (we were in IMC mode on the HUD with a -3.00 glideslope angle and the TDZE set in the altitude). I left the autopilot engaged to see if the automation was going to correct the low situation. I crosschecked the instruments and the lateral and vertical navigation pointers were centered in the middle. As the white PAPI started to change color to red; I disconnected the autopilot and corrected the aircraft flight path back to 2 white/2 red on the PAPI. The vertical guidance (GP) indicator for the RNAV on the instruments then showed us high when the PAPI showed us on the proper glide path. I do not remember seeing the ILS indication during the event. I feel confident that we both had the ILS Localizer frequency and course set; but I did not look for the glideslope during the event. The landing was uneventful. After arrival at the gate; I asked Ground Control 'what was the altimeter indicating'; and they said '29.94 and falling rapidly.' I estimate this altimeter was provided at XB35 Z.

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.