Narrative:

On arrival at ZZZ; we did a complete briefing of the arrival and approach we were performing. Of particular note; we briefed about the fact that the transition level was not specified on the ATIS but the transition altitude was on the arrival procedure page. Since this altitude was 8000 feet; we expected our transition level to be no less than FL090. During the approach ATC gave us a shortcut clearance along with altitude and ILS approach authorizations. Even though we were expecting this process and prepared by reducing speeds for configuring the aircraft; in the busy steps of setting up the approach; the change of the altimeter setting to query nautical height (qnh) was missed. We were above all the appropriate altitudes during the complete approach in VMC conditions with the terrain and airport in sight. We were fully established; on profile and stabilized by 1500 ft AGL. At about 500 ft AGL; we received an unexpected ground proximity warning system (GPWS) terrain warning which did not match our position based on visual indications and navigation information from the ILS signal. The warning only activated once; and because we were in a safe position; we continued to a safe and uneventful landing. After we parked at the gate we debriefed the occurrence and concluded that it must have been false indication as a previous bulletin specified about this airport. Later in the day; as we again discussed the events; is when we realized about the failure to set the altimeter to the correct setting. Even though I wrote it up in the logbook as a system malfunction; I now believe it could have been caused by the incorrect altimeter indication.

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Original NASA ASRS Text

Title: B-767 crew reported a GPWS 'Pull Up' command on an ILS approach in VMC. The crew assessed that since they were VMC and the runway was in sight; they could safely land. During post-flight debriefing; they realized that their altimeter settings had been incorrect.

Narrative: On arrival at ZZZ; we did a complete briefing of the arrival and approach we were performing. Of particular note; we briefed about the fact that the transition level was not specified on the ATIS but the transition altitude was on the arrival procedure page. Since this altitude was 8000 feet; we expected our transition level to be no less than FL090. During the approach ATC gave us a shortcut clearance along with altitude and ILS approach authorizations. Even though we were expecting this process and prepared by reducing speeds for configuring the aircraft; in the busy steps of setting up the approach; the change of the altimeter setting to Query Nautical Height (QNH) was missed. We were above all the appropriate altitudes during the complete approach in VMC conditions with the terrain and airport in sight. We were fully established; on profile and stabilized by 1500 ft AGL. At about 500 ft AGL; we received an unexpected Ground Proximity Warning System (GPWS) terrain warning which did not match our position based on visual indications and navigation information from the ILS signal. The warning only activated once; and because we were in a safe position; we continued to a safe and uneventful landing. After we parked at the gate we debriefed the occurrence and concluded that it must have been false indication as a previous bulletin specified about this airport. Later in the day; as we again discussed the events; is when we realized about the failure to set the altimeter to the correct setting. Even though I wrote it up in the logbook as a system malfunction; I now believe it could have been caused by the incorrect altimeter indication.

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.