Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 180; Flight Crew Type 18000
Distraction; Workload; Time Pressure; Human-Machine Interface
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Procedure; Chart Or Publication
Approaching EMMRL on the DSNEE 4 Arrival to SNA; we elected to brief and fly the RNAV Z 20R Approach with clear weather. The approach branches from the arrival at point DSNEE. At that point; the arrival continues to point JWARD with a mandatory altitude of 7;600 feet. The RNAV Z 20R branches on a different track to BONVY with a 6;000 feet mandatory altitude. The 7;600 feet mandatory altitude after the branch point sets an altitude constraint in the FMC and prevents loading the RNAV approach. The approach loads in reverse video. To load and brief the approach requires deleting the clearance limit altitude from the DSNEE 4 and sets the Crew up for altitude crossing non-compliance. This requires the Crew to modify the approach and takes system automation out of the loop in the high traffic; high terrain area northeast of SNA where it is most needed. Additionally; despite requesting RNAV Z on initial contact with Approach; they had to call another frequency for this clearance. We weren't cleared the approach until about three miles prior to the branch point.
B737-700 Captain reported being unable to load the RNAV approach in the FMC because of a mandatory crossing restriction on the arrival.