I think we need to make careful distinction between systems here. For example, I doubt anyone would seriously question the usefulness of GPWS or TCAS and their beneficial effect in reducing the probability of CFIT and mid-air collisions respectively. Similarly, lateral autopilot modes appear to bring about significant benefits in pilot workload and navigation accuracy without causing problems.
From reading through accident reports and the comments on various PPRuNe threads it seems to me that the problems lie primarily in two areas:
- Misuse or mismanagement of VNAV autopilot modes, particularly if autothrottle is used at the same time;
- Some of the deeper and more complex aspects of flight envelope protection logic in FBW systems, particularly failure modes, and especially if the air data system is compromised.
What do people think about focussing the debate on to these aspects, or should it be wider?