Flight Crew Air Transport Pilot (ATP)
Workload; Fatigue; Situational Awareness
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Flight Crew Became Reoriented
Procedure; Human Factors
The flight was an early morning report; but there were no errors leading up to the event.  On the arrival briefing; I mentioned we use white-needles to give us vertical guidance; since the ATL 9R Glide Path (GP) was Out of Service (OTS); the Captain agreed.  While being vectored by ATC; we had a tailwind of about 12 knots.  ATC was busy trying to sequence all the early arrivals into ATL.Due to their workload; we received a late vector to intercept the localizer and we were going through the course by 1/2 scale.  The Captain disengaged the autopilot to correct this error.  While I was watching him correct course; ATC issued traffic at 1 o'clock.  The TCAS was deferred; so I dedicated my monitoring for the traffic.  ATC then gave us a speed reduction to 210 knots then descend to 3;000.  At this point; I glanced at the snowflake and saw us 1 dot above.  ATC then asked for the traffic again; but there was no contact.  We were high so the Captain wanted auto-pilot on and vertical speed to catch the snowflake.  He then asked to put a fix behind us; so I did because we were getting busy.  I should have queried him; because this caused the snowflake to disappear.  ATC then assigned a speed reduction to 180 knots and I was concentrating on why the snowflake dropped out.  Immediately; the Captain called for flaps 8 and flaps 20.  When I went to look up again; he called for gear down.  I was able to look up again quickly and my mind saw the red PAPI; but then the Captain called for flaps 45; landing check before I could process it.  I then completed the landing check and when I put the checklist back; I saw 4 red PAPI lights.  The Captain also saw this and we leveled off at 2;200 feet at BURNY.  We were able to continue normal stabilized approach to landing; after that.  Tower informed us of a low altitude alert and loss of communication with approach.The threats consisted of a very early departure time; night; ATL 9R GP OTS; and a late vector to final by ATC; being rushed.  The error was not looking visually at the PAPI outside to cross-check the vertical path.  The undesired aircraft state happened because of multi-tasking; being rushed; communication with ATC; and operations that were not normal with the glideslope out.From this event; I would make a company policy to not touch the FMS below 4;000 feet; if it was already 'cleaned up.'  Additionally; with GP OTS I would include brief items for vertical path cross-check with the PAPI more than usual.
A CRJ-200 First Officer reported a low altitude event on approach to ATL Runway 9R when the crew lost situational awareness and descended below the glideslope.