Date: 201402
Local time of day: 1201-1800
Location: OMA.Airport, NE
Flight conditions: VMC
Weather elements / visibility: Cloudy; Snow
Light: Daylight
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class C OMA
ATC / advisory: TRACON OMA
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Physiological - Other; Communication Breakdown; Distraction; Human-Machine Interface
Second reporter function: Captain; Pilot Not Flying
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Contributing factors: Weather; Human Factors
Primary problem: Human Factors

Narrative: ATC assigned 'Fly current heading to intercept the localizer; maintain 3;000 FT until established; cleared the ILS 32L'. At this point we were VMC; but had a cloud deck between us and the airport. Upon reading back the clearance; the Captain armed approach mode and stated it was armed. I verified the automation mode and began looking outside for the airport. The Captain must have then set 2;000 in the altitude alerter. As I was looking outside; having trouble finding the airport in the snow (exaggerated by the fact that there was a white cloud above; and smooth-featureless snow below); I began to feel that the aircraft descent was not appropriate to our location on the approach. I looked back inside at the PFD; and realized that we were descending through 2;600 FT. At this point we were approximately 3 miles outside of RIKKY (2;800 FT MSL) on the approach. I questioned the Captain and informed him that RIKKY was a hard altitude of 2;800 FT; and asked him if we had been cleared for a visual approach and if I had missed that radio call. The Captain looked at the chart and immediately leveled off altitude. He realized his mistake and initiated a climb back towards 3;000 FT. As soon as the Captain began correcting the error; ATC called us and gave us a 'low altitude alert'. I responded that we were correcting to 3;000 FT. ATC then asked us if we had the airport in sight. Having picked up the airport visually; I verified with the Captain that he had it visually as well; and confirmed with ATC that it was in sight. ATC then re-cleared us for the visual approach to 32L; and we landed without incident.Post-flight debrief of the incident with the Captain revealed that he had heard the clearance; but confused the '2' in '32L' for a clearance of 2;000 FT and cleared for the approach. Another threat I later learned was the Captain had recently moved to the 700/900; and was having some difficulty adjusting to the louder cockpit environment (due to the loud avionics fans). My error as the pilot not flying was in not catching him changing the altitude alerter. I allowed the challenging snow-covered terrain to consume too much of my attention as I looked for the airport. Clearly the aircraft instrumentation needed more of my attention. An obvious undesired aircraft state was that the airplane was allowed to descend below a published altitude on the approach. Even in VMC conditions and on a visual approach; aircraft should be maintained at or above published IAP altitudes.This situation taught me to not focus too much on any one aspect of the aircraft operation. By focusing too hard on finding the airport; I apparently neglected my cross-check of the Captain's altitude input. Even when flying with a skilled Captain such as this; it is possible for a mistake to be made in a seemingly mundane portion of the operation. I learned that even the seemingly simple instructions from ATC can be heard incorrectly by another pilot. Another lesson learned today was that while it is important to find the airport; it's not all that important when just starting an approach. My priorities have changed. I will now be ensuring the aircraft is thoroughly established on the approach with all automation inputs verified correct prior to 'going outside' to find the airport. I will also be adapting my instrument scan to allow some time 'outside' for spotting the airport without neglecting the 'inside'.


Second narrative: I noticed once or twice before on this flight that I had to ask my First Officer to confirm an altitude or repeat something to me. I very recently transferred over from the CRJ200 to the CRJ700/900. I am not used to the amount of noise in the flight deck caused by the Avionics Cooling Fans. In the future; I will ensure that the volume is set to a higher level so that I hear all communications better.


Synopsis: A CRJ700 flight crew descended below their glideslope intercept altitude prior to intercept after being cleared for the ILS. The Captain had misunderstood a clearance and changed the altitude alert to 2;000 MSL vice 3;000 as actually cleared. High ambient cockpit noise level was cited as a contributing factor.