Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP)
Distraction; Situational Awareness
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Human Factors
The altitude deviation occurred while being vectored to final for the ILS 19R into MKE. While on a base vector I noticed that neither of our ghost needles had popped up so I went heads down into the FMS to make sure the right approach was loaded. It was not so I began loading the ILS 19R during the high workload situation. The most current altitude clearance at that time was to 2800 feet which was the GS intercept altitude. At some point while loading the correct approach we were given a new clearance with an intercept heading of 220; maintain 2800 feet until established; cleared for the ILS 19R approach. Once established on final ATC reiterated to maintain 2800 feet at which point I looked at the altitude selector set to 2100 feet for unknown reasons. I replied to ATC that we were climbing back up to 2800 feet at which point he sent us over to tower.The deviation was brought to our attention when ATC repeated that our clearance was to maintain 2800 until established. At that point I looked at the altitude selector and saw the wrong altitude selected. The event occurred because I was fixing a mistake I made earlier in the flight; my first officer was task saturated; and we did not follow SOP for altitude changes and confirmation. I was not made aware or realized that he had selected a new altitude in the altitude selector. We climbed back up to our assigned altitude and continued the approach with no further issues. This could have been prevented had I not been distracted by the FMS and we had followed SOPs when selecting a new altitude.
I was almost task saturated due to low experience level in light ice; turbulence; and full IMC approach together. Continuous changes of headings and altitudes brought me to incorrectly select 2100ft on the altitude selector. In the future I will overcome confusion by reinforcing altitude selections and confirmation procedures as stated in [company] manuals.The event occurred because PM had selected an incorrect approach early on during flight and was focusing on fixing it during final vectors moments of the approach. I was task saturated and incorrectly select wrong altitude without confirmation from PM as SOPs procedures require. After descent to 2100ft we realized it was a lower altitude than the minimums for the approach and climbed back up to 2800ft. I will put more emphasis on SOPs procedures when selecting an altitude to receive a confirmation by PM.
CRJ-900 flight crew reported descending below cleared altitude on approach to MKE due to distractions; workload; and failure to follow SOP.