Crj-900 first officer reported descending below a transition crossing altitude on the bos ROBUC2 arr...

Narrative:

The FMS was occupied by the non-flying pilot. I set the mfd range too broad and the names of waypoints and altitudes were not clear; and for a brief second I was using the arrival chart alone for guidance from one waypoint to the next. On the ROBUC2 arrival into bos; I was flying and descended to 11;000 ft for waypoint provi; and then proceeded to set 8;000 for ansly because at the time the captain was using the FMS and I set the mfd to a range that was too broad so the wording was not too clear. I looked over to my ipad chart for ROBUC2 and it is rather confusing for the arrival into the several runways. The lines for each waypoint after provi take you to different arrivals for the different runways. For example joody takes you to 4R; jayna takes you to 15R; and I thought krann takes you to runway 27 and ansly for runway 22L but I got those two last mixed up krann and ansly. I was supposed to stay at 11;000ft for krann. So I was descending close to 10;000 when the captain and I realized the mistake and we expedited a climb back to 11;000 ft. There was no incident or traffic. We proceeded to finish the arrival; landing; and taxi to gate safely.charts with overlapping lines for waypoint to waypoint should be different colors to differentiate which is the one on the runway specific arrival.

Original NASA ASRS Text

Title: CRJ-900 First Officer reported descending below a transition crossing altitude on the BOS ROBUC2 Arrival. They attributed the error to missetting the Multifunction Display range and confusing chart presentation.

Narrative: The FMS was occupied by the non-flying pilot. I set the MFD range too broad and the names of waypoints and altitudes were not clear; and for a brief second I was using the arrival chart alone for guidance from one waypoint to the next. On the ROBUC2 arrival into BOS; I was flying and descended to 11;000 ft for waypoint PROVI; and then proceeded to set 8;000 for ANSLY because at the time the Captain was using the FMS and I set the MFD to a range that was too broad so the wording was not too clear. I looked over to my iPad chart for ROBUC2 and it is rather confusing for the arrival into the several runways. The lines for each waypoint after PROVI take you to different arrivals for the different runways. For example JOODY takes you to 4R; JAYNA takes you to 15R; and I thought KRANN takes you to runway 27 and ANSLY for runway 22L but I got those two last mixed up KRANN and ANSLY. I was supposed to stay at 11;000ft for KRANN. So I was descending close to 10;000 when the captain and I realized the mistake and we expedited a climb back to 11;000 ft. There was no incident or traffic. We proceeded to finish the arrival; landing; and taxi to gate safely.Charts with overlapping lines for waypoint to waypoint should be different colors to differentiate which is the one on the runway specific arrival.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1414621
Time
Date	201608
Local Time Of Day	1801-2400
Place
Locale Reference	BOS.Airport
State Reference	MA
Environment
Light	Night
Aircraft 1
Make Model Name	Regional Jet 900 (CRJ900)
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR ROBUC2
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Crj-900 first officer reported descending below a transition crossing altitude on the bos ROBUC2 arrival. They attributed the error to missetting the multifunction display range and confusing chart presentation.