Date: 202103
Local time of day: 1201-1800
Location: ZLA.ARTCC, CA
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class A ZLA
ATC / advisory: Center ZLA
Aircraft component: Electronic Library (other than Nav database)
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Human-Machine Interface; Communication Breakdown
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Contributing factors: Human Factors; Aircraft; Chart Or Publication
Primary problem: Chart Or Publication

Narrative: As pilot monitoring; I was handling the radios. Center cleared us for the 'RNDRZ 1 arrival Runway 26L' which I read back. We had set up for that arrival and runway; validated it; and briefed it thoroughly to include the issues with turning early if cleared for the visual which presented a terrain problem. Upon selection of the Runway 26L runway and the RNDRZ 1 arrival in the box; the aircraft automatically selected the Runway 26L transition which we understood we were cleared for. The Captain and I both verified with the other that we were cleared for the transition and we agreed that what the box presented to us was what we were cleared for. At the waypoint BERBN the jet turned onto the Runway 26L transition as planned. We received a radio call to turn back to a 130 heading and then given subsequent vectors to final and landed without incident. We were told by ATC that we should not have turned onto the transition. Looking back over the arrival and approach plates again and again; I still think we did what we were cleared for. If receiving the clearance for the 'RNDRZ 1 Runway 26L' doesn't mean clearance for the Runway 26L transition I'm not sure what does. Such verbiage at other airports indicates clearance onto the transition. The arrival plate is confusing however because at BERBN it directs the reader to 2 different things at once. It directs the reader to the Runway 26L transition found on the approach plate and also the possibility of continuing on the present heading to expect vectors to final. Even with that; to be cleared for the arrival and runway has always meant cleared for that runway's transition. Furthermore; the transition does not connect with the approach to Runway 26L giving greater weight to the fact that one need not be cleared for an approach to be cleared for the transition. I believe the Captain and I did exactly what we were cleared to do and that our understanding of that clearance corresponds to our experience and training.Causal factors were incorrect chart depiction and the aircraft navigational system automatically linking the Runway 26L transition when that arrival and runway are selected.Chart needs to be revised to make clear when the transition is to be used and when not. The aircraft navigation system needs to be updated to reflect how ATC wants the approach flown.




Synopsis: Air carrier First Officer reported a track deviation while on the RNDRZ1 Arrival Runway 26L to LAS Airport.  First Officer stated the arrival chart depiction and aircraft navigation system automatically linked the Runway 26L transition when that arrival and runway were selected.