Date: 201912
Local time of day: 0601-1200
Location: EWR.Airport, NJ
Flight conditions: Marginal
Weather elements / visibility: Snow
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Final Approach
Airspace: Class B EWR
ATC / advisory: Tower EWR
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Confusion; Situational Awareness
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Tonight we shot an approach in strong gusty cross winds to minimums in blowing snow at EWR. The first error we made was a tough call where we technically should not have descended on the approach but we did and here is why. Shortly before going to tower; we had been told verbally by approach control about the new ATIS info 'E' which had vis reported at 1.5 miles-SN FEW1200 BKN3200. Just before glideslope intercept between GIMME and the FAF (BUZZD) we checked in with Tower and had just heard the RVR 1600 and we were cleared to land. With the dramatic change in visibility from 1.5 miles to 1600 RVR; it did not register that ILS RWY 22L min RVR for us was 1800. The threat was that this occurred at a point where we were communicating with tower; slowing; configuring and approaching glideslope. We began the approach and subsequently heard another RVR - now 2200 approach end; however we clearly should not have started the descent on the approach. This was an error however that was not a significant risk to continue to minimums and go around if not visual at that point. Procedurally with more time to process the significant change in visibility from 1.5 miles to RVR readings we would have coordinated missed approach procedures. However as we continued there was a safe way to correct the error and improve our CRM if not visual at DA. We did continue to minimums and made standard calls of 1000; 500; and approaching minimums. Captain called visual; runway in sight prior to minimums about 250' AGL and when he stated visual he asked me to watch the glideslope. The error (in my opinion) we made was that neither of us called go around when we heard an aural GPWS 'sink rate' call below 500'. I only heard it one time and had visual references with the touchdown zone the whole time. Upon reviewing the flight manual's GPWS profiles; it states 'For 'sink rate' and 'Glideslope' warnings at or below 500 feet AGL/RA: [PF] Execute missed approach. Unless in visual conditions and the Captain determines that the momentary deviation is being immediately and safely corrected.' During the debrief the Captain told me he adjusted the glide path visually to ensure landing at 1000 ft. and not land long because he was concerned about braking action. We fully debriefed the error with regard to descending on the approach when reported RVR was below minimums; yet understood the reason this error occurred was due to high workload and previously reported weather giving no indication visibility would be anywhere near that low. I felt the Captain flying did call visual prior to the aural 'sink rate' and he immediately and safely correct his decent rate. However; with the lower visibility and strong crosswind if I had that to do over; I would have called go around.




Synopsis: First Officer reported not executing a required missed approach when the reported RVR dropped momentarily below minimums.