B757-200
Communication Breakdown
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
General None Reported / Taken
Human Factors; Procedure
Redeye arrival to LAX Runway 6R. ATC cleared us to 'descend via.' We had leveled off for an extended segment at 10;000 FT as charted; when ATC cleared us 'after SMO descend to 4;000 FT.' Both of us interpreted this to supersede other altitude restrictions on the arrival and ILS 6R; including SMO at 8;000 FT; and WAKER at 5;100 FT. Accordingly; we crossed SMO at 10;000 FT; set 4;000 FT in the ALT window and began descent. Shortly thereafter we were cleared for a visual approach to 6R. All concluded with no complaints from ATC. However; I am now wondering. 1) Should we have crossed SMO at 10;000 FT - altitude at the time of revised clearance -- or 8;000 FT as published?  Did the revised clearance supersede the previous 'descend via?' 2) Should we have stopped descent at 5;100 FT until passing WAKER then descended to 4;000 FT?  The circumstances render these questions somewhat academic; since we were just dropping in on a visual approach with no conflicting traffic. A simple addition to the clearance by ATC would have helped; i.e. 'cross SMO at 10;000 FT; then descend to 4;000 FT' or 'cross SMO at 8;000 FT; then descend to 4;000 FT.'
Air Carrier arrival into LAX posses a number of questions regarding ATC's clearance during an approach to Runway 6R.