Regional Jet 700 ER/LR (CRJ700)
Flight Crew Commercial
Troubleshooting; Human-Machine Interface; Distraction; Confusion; Communication Breakdown; Workload
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Flight Crew FLC Overrode Automation; Flight Crew Took Evasive Action; Flight Crew Returned To Clearance
Aircraft; Human Factors; Company Policy
While flying [our] aircraft [a CRJ700] we noted that the fms has different software; arrivals; approaches etc. seem to load differently. Extra fixes are added even when just selecting a runway. We were on the JAWBN2 arrival into Seattle. The JAWBN2 was loaded in the fms. We selected the appropriate runway and transition. Upon receiving clearance to descend via the JAWBN2 the captain initiated his descent to 12000 [FT]. Very shortly after we both noticed at the same time the south transition was loaded. The pilot flying disconnected the autopilot and climbed back up to our assigned altitude. We scrolled through the fms and noticed the south transition was first then a discontinuity then the north transition and another discontinuity. We never loaded a south runway in the first place. There was no loss of separation or any tcas messages. ATC did not get involved either. After later toying around with this specific fms; we noticed it automatically enters more fixes than usual while selecting arrivals or runways. It also creates multiple discontinuity's further down the pages unlike every other fms in the our airline's fleet. It has other unique features like autotuning the ils frequencies and activating them. Our unfamiliarity with this different software I believe caused this problem.  We should be made aware of differences in aircraft software to avoid simple mistakes that could lead to an unsafe condition. For example we have received bulletins on other differences these planes have (once operated by a different airline).
A CRJ-700 First Officer noted a specific aircraft's FMS loaded both north and south JAWBN STAR waypoints with discontinuities even though only the north transition was selected. This aircraft's FMS software is apparently unique to this aircraft and creates an additional distracting workload.