Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Instrument
Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overrode Automation
Software and Automation; Procedure; Human Factors; Airspace Structure; Chart Or Publication
No violation occurred. We found a potential issue with an arrival and approach into Las Vegas. We were descending via the RNDRZ 1 Arrival into LAS. The bottom altitude at ROAMN is 8;000 ft. Prior to reaching ROAMN; we were cleared to join the localizer for the ILS1L after ROAMN. This approach has a ROAMN as the IAF/transition. When we closed the discontinuity to hook up ROAMN (common waypoint on the STAR and approach); the hard altitude of 8;000 ft. (per the STAR) dropped from the flight plan. The VNAV recalculated the descent; which would have left us about 600 ft. high over ROAMN. I pointed this out to the Captain (PF( Pilot Flying)) who then reprogrammed the FMS and added 8;000 ft. back as a hard altitude at ROAMN. I looked at several other STAR/approach combinations that all have common waypoints. For each one I found; both the STAR and the approach list the common way-point with the same hard altitude. The 1L ILS does not list ROAMN with a hard altitude of 8;000 ft. even though it is on the STAR. Does this need to be updated ? If not; when cleared for the approach prior to the IAF; are you relieved of the hard altitude on the STAR if the IAF isn't listed with one as is the case here?
First Officer reported confusion interpreting a clearance transitioning from a STAR to the ILS Approach.