B737-300
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 142; Flight Crew Type 26000
Distraction; Human-Machine Interface; Training / Qualification; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Other / Unknown
Flight Crew Overcame Equipment Problem
Aircraft; Chart Or Publication; Human Factors; Procedure
While descending through approximately 12;000 MSL and approaching PTEES on the BOOSH RNAV STAR to STL; Approach told us to expect Runway 12L versus 12R for landing. The pilot flying changed the FMC without verbalizing anything which resulted in a VNAV disconnect and route discontinuity. As pilot not flying; I immediately verbalized setting 10;000 in the MCP Altitude window and stated the PTEES restriction and mileage to go. The pilot flying acknowledged; using MCP level control; finished his inputs; and linked up the proper sequence in the FMC and then the pilot flying re-engaged LNAV and VNAV. The pilot flying verbalized resetting the MCP to the descend via altitude that we had been cleared to and the rest of the arrival was without incident.Our [flight crews] do not adequately know how the FMC controls the aircraft through LNAV and VNAV. Our depth of knowledge is dangerously thin; especially as more and more RNAV procedures are introduced. My reflex action to always put the next altitude restriction in the altitude alert is borne from constant misapplication of inputs into the FMC whenever ATC changes anything--and not knowing what the effect will be. The verbalize; verify; and monitor technique quickly goes out the window when ATC revises [a terminal RNAV procedure]. And they do. The FMC profile is awkward in accommodating dynamic change and our collective minimal training and experience is inadequate to the rigors of everyday life on the line. Speed changes; runway changes and; in the case of DEN; 150 NM of constant changes leave the probability of error high. I can't be the only pilot seeing this problem on the line.
A B737-300 Captain lamented the training deficiencies at his airline that he believes ill prepares flight crews to effectively conduct complex terminal area RNAV procedures.