Thanks Brian, Owain and PJ2 (aviator-philosopher!).
Overall, the illuminating side of this discussion has been well worth the comparitively minor hassle of Dozy's "faint, buzzing noise, like an angry wasp banging against a window."
There are many fine contributions here, but one must particularly admire Owain's and AirRabbit's insights into design and certification, and it's good to see Machinbird back. Where are all the other usual suspects?