Medium Transport
Flight Crew Instrument; Flight Crew Multiengine
Distraction; Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter CFTT / CFIT
Flight Crew Executed Go Around / Missed Approach
Human Factors
We were cleared for the ILS roughly 20 miles from the airport and assigned 170 KTS. We configured flaps 20 and gear down to maintain speed and separation with lead aircraft on the approach. Just after FAF the Captain and I noticed that the altimeter were 100 feet off. This was due to an incorrect altimeter setting on my side. When I switched the navigation source to the localized I had changed the altimeter instead. I thought I had fixed it back to the proper setting but failed to cross check as we were entering the approach. As we continued on the approach we received a 'pull up; terrain' warning. It was at this point I recognized that the flaps were improperly set and we executed the go around. We were busy on the approach and had been slowed early. Improper altimeter distracted us acutely around FAF. Ensure crosscheck by crew any time improper inputs are made.
Air carrier First Officer reported distraction of incorrect altimeter setting resulting a terrain warning.