Narrative:

Completed zzzzz 3 STAR heading northwest; instructed to descend to 6000; then instructed to turn right 030 and descend to 4000 inside ZZZZZ1 intersection then very quickly instructed to turn to 110 heading and cleared for the ILS xxr approach; maintain 4000 until established. I was hand flying using the flight director. Once cleared I attempted to switch to green needles and asked for the fcp to select appr mode. I overshot the localizer by about a 1/4 deflection. Captain immediately instructed me to continue turn back to localizer. During the turn we descended to about 3200' between ZZZZZ1 and ZZZZZ2; 3 things I believe contributed to this event. Relatively quick instructions from ATC to transition from the zzzzz 3 STAR from the northwest heading. My recollection was first right turn to 030 and descent to 4000 then right turn to 010 and clear for the approach. Second; PF [pilot flying] failure to anticipate what ATC was planning to instruct me to do. I should have anticipated that we could be instructed very quickly to turn base then final inbound and descend in quick succession. Third; we were still IMC while descending on the base leg prior to turning final then instructed to turn to 110 just at that time we broke out and it was visual conditions but I believe we did not call airport in sight. I was trained to switch from white (GPS) needles to green localizer needles when turning inbound then select approach mode when cleared for the approach. When I reached down to switch needles from white to green I first accidentally selected the baro knob then reached up and selected the navigation knob. I turned the navigation knob right but needed to turn it left which distracted me momentarily and caused another slight delay in my turn inbound. A confusing aspect which was explained to me after landing is with two FMS's you turn one click left to select green and with one FMS full right to select green. I was unaware of this difference and instinctively went right turn which did not select the green needles. I then switched back left and finally got the green needle. These two very short distractions and delays was enough for me to not turn inbound on the localizer at the correct time and I overshot the localizer course inbound about a 1/4 deflection. I need to brief with the captain prior to an approach to make sure that person is clear on how I plan to execute the approach. I also need to brief myself on the unique function of each aircraft so I know which direction to turn based on the equipment installed in each aircraft. During training all the sims are simply one click left on the first officer [first officer] side to go from white to green needles. After the flight my captain who was excellent informed me there is a difference between single and dual FMS equipped aircraft with regards to that technical step. I felt prepared and ready to make this approach but need to continually try improve my ability to think ahead and anticipate we may get instructions from ATC earlier and quicker than I was anticipating.

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Original NASA ASRS Text

Title: CRJ200 First Officer reported confusion changing selection on FMC resulted in excursion from altitude and track.

Narrative: Completed ZZZZZ 3 STAR heading NW; instructed to descend to 6000; then instructed to turn right 030 and descend to 4000 inside ZZZZZ1 intersection then very quickly instructed to turn to 110 heading and cleared for the ILS XXR Approach; maintain 4000 until established. I was hand flying using the flight director. Once cleared I attempted to switch to green needles and asked for the FCP to select APPR mode. I overshot the localizer by about a 1/4 deflection. Captain immediately instructed me to continue turn back to localizer. During the turn we descended to about 3200' between ZZZZZ1 and ZZZZZ2; 3 things I believe contributed to this event. Relatively quick instructions from ATC to transition from the ZZZZZ 3 STAR from the NW heading. My recollection was first right turn to 030 and descent to 4000 then right turn to 010 and clear for the approach. Second; PF [pilot flying] failure to anticipate what ATC was planning to instruct me to do. I should have anticipated that we could be instructed very quickly to turn base then final inbound and descend in quick succession. Third; we were still IMC while descending on the base leg prior to turning final then instructed to turn to 110 just at that time we broke out and it was visual conditions but I believe we did not call airport in sight. I was trained to switch from white (GPS) needles to green localizer needles when turning inbound then select approach mode when cleared for the approach. When I reached down to switch needles from white to green I first accidentally selected the BARO knob then reached up and selected the NAV knob. I turned the NAV knob right but needed to turn it left which distracted me momentarily and caused another slight delay in my turn inbound. A confusing aspect which was explained to me after landing is with two FMS's you turn one click left to select green and with one FMS full right to select green. I was unaware of this difference and instinctively went right turn which did not select the green needles. I then switched back left and finally got the green needle. These two very short distractions and delays was enough for me to not turn inbound on the localizer at the correct time and I overshot the localizer course inbound about a 1/4 deflection. I need to brief with the Captain prior to an approach to make sure that person is clear on how I plan to execute the approach. I also need to brief myself on the unique function of each aircraft so I know which direction to turn based on the equipment installed in each aircraft. During training all the sims are simply one click left on the FO [First Officer] side to go from white to green needles. After the flight my Captain who was excellent informed me there is a difference between single and dual FMS equipped aircraft with regards to that technical step. I felt prepared and ready to make this approach but need to continually try improve my ability to think ahead and anticipate we may get instructions from ATC earlier and quicker than I was anticipating.

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.