One of the traps people fall into when discussing Engineering is this – Software Engineering is primarily a design/refine activity, where the more established Engineering disciplines are design/construct.

The problem with Waterfall is that information is lost whenever there is a hand-off activity. The effort that must be expended to reduce that loss can be enormous – volumes and volumes of specifications, design description documents and test plans.

If you don’t want to expend that energy, then you can’t use waterfall, or you will almost certainly fail, eventually.

However there is nothing to stop you using Agile techniques in delivering safety critical software, you have the advantage however that your requirements are more solid, the problem is more defined. The deliverables produced is just going to include a lot more documentation, and a lot more planned defined testing.

I see Craftsmanship as one of the tools or techniques that can be applied to an Engineering problem where that problem domain is not fully understood or described.