EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Distraction; Human-Machine Interface
Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Human Factors
About 3/4 of the way to [destination] at night; loss of MFD1; PFD2; FMS2; and COM2 blank on RMU2. EICAS only displayed messages: Check PFD2 and RA2 Fail. Followed QRH; no guidance on how to restore screens. Turned on dome and checked for popped circuit breakers. Moved seats forward and looked for popped circuit breakers. Discussed with CA (Captain) possibility of DC2 BUS failure. Looked over QRH procedure for DC2 off BUS. We did not get DC2 off BUS EICAS and on MFD; DC2 BUS still showed connected to electrical system. At this point we were then cleared to descend via STAR landing south. We notified ATC of lack of half navigation/communication systems and requested a descent in lieu of descending via. We were cleared to continue on route but ATC gave us step down altitudes to descend to. There was also a line of weather between us and the field at this point. [Destination] METAR had thunderstorms in the vicinity but ceiling was greater than 3000 ft. We requested the visual and were cleared for the approach. At around [10 NM from airport]; CA noticed a momentary flicker of avionics master 2. CA turned on dome and found avionics master 2 to be deselected but without white bar across button. The light turbulence we went through was enough of a jolt to momentarily illuminate the avionics master 2 button. CA tested all lights in avionics master buttons and lights worked. Somehow in flight at cruise avionics master 2 popped out without displaying the white bar across the button. It was very dark in the cockpit at this point as we had a higher overcast layer and were entering a line of weather on the arrival. CA pushed avionics master 2 as we passed [10 NM point on approach] and screens were restored and EICAS messages went away. Landed and parked at gate normally.Pilot selectable buttons failing without indication. No guidance from QRH in that situation. Weather encountered as the failure occurred. The amount of darkness in the cockpit made it impossible to visually tell the button was out. It would have been easy to lose situational awareness as we lost half our screens and were preoccupied with running QRH. CA flew the aircraft; and I let ATC know of our situation and limitations. We were initially cleared to descend via; but as a crew we decided that workload would be more than we were comfortable with in that situation and so we asked for step downs. ATC accommodated that request and offered to help however they could should we have needed it. I have learned from this experience to expect that when the aircraft breaks; it may not give you an indication that it is broken. If the avionics master button is deselected for some reason; it should display a white bar; in our case it did not. This fleet is aging and sometimes things don't work the way they were designed to work.
ERJ145 First Officer reported an inflight flight display and navigation systems failure due to Avionics Master2 breaker being popped out.