B737-700
Flight Crew Last 90 Days 173; Flight Crew Type 3450
Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Human Factors; Chart Or Publication
This was the Captain's leg to LAX. The arrival was programmed to 25L; since the RIIVR2 Arrival only depicted approaches to the left (South) runways. Both the Captain and myself are back to flying after extended leaves of absence; and this was only my second trip into LAX in over two years (lack of familiarity with this RIIVR2 depiction anomaly). The Captain stated this had been a problem before; but we did not talk about specifics.Once we had started our descent from FL250 (final cruise) to an initial altitude of FL190; we were told to expect Runway 24R. The Captain reprogrammed the box to match the change and then he briefed the changes and I followed along on the LEGS page. I apologize for a lack of specific waypoints; I do not have the arrival in front of me. However; the third or fourth waypoint he read was not in the LEGS page and neither were the most of the subsequent waypoints. He asked me to type the missing point in; but since there were multiple points and altitudes missing; I initiated reloading the arrival; transition and approach. I missed the approach transition the first time; (RIIVR wasn't an option); but was able to get the FMC to match what we anticipated flying. During the effort; we were given a descend via clearance; but the box didn't match and a lower altitude was not placed in the MCP window (still set at 190). The prevailing problem was that both pilots were heads down and not putting enough attention into monitoring the automation. Once the box was satisfied; we both recognized that we had not started a descent and VNAV had disengaged. Quickly after; I noticed that we were not on course. We were correcting to course when LA or SoCal called us; also recognizing that we were not on the arrival. They gave us a heading (170; I think) and direct to SKOLL; which was beyond a few of the initial arrival points and LA also gave us a descent. No altitude restrictions were missed; since they were at or above altitudes; but we were high on profile and were never again able to get back in VNAV PATH and I felt rushed the rest of the flight; even as the Pilot Monitoring. As I was modifying the flight plan to get the right arrival and approach loaded; I did not execute until we were both in agreement on the route. I think we must have reached a point in the plan that had a discontinuity (prior to final clean up and execution) and LNAV disengaged.  I recognized the VNAV disconnect and that we needed to get going down first; then that we were off course; then that LNAV was disengaged. We never knew definitively why LNAV had disengaged. All of these events happened leading up to and shortly after the GRAMM waypoint. The rest of the flight was uneventful.I think that the RIIVR2 should show transitions to both sets of runways. If we had entered what we wanted to fly from the beginning; we would not have been making changes in a rushed manner during the descent. I don't remember this being a problem when I flew into LAX two years ago. Why was the graphic changed?
B737-700 First Officer reported deviating from the RIIVR2 arrival to LAX when they had difficulty programming the FMS and the aircraft dropped out of LNAV.