C is Brittle D is Plastic

[Walter Bright]

On 4/8/2026 1:48 PM, Richard (Rikki) Andrew Cattermole wrote:
> Given how prevalent software is now in aerospace, the fact that planes aren't 
> falling out of the sky on a regular basis is pretty incredible. No amount of 
> hardware can make up for how invasive it is.

Having done design work for 3 years at Boeing, I can tell you that the software 
does fail. So does the hardware. And so does the nut behind the wheel.

The reason planes don't fall out of the sky is:

* backup systems and workarounds *

(I don't know how often this happens, but airplanes are given the green light to 
fly even when many things are broken. There is a "minimum equipment list" which 
specifies what cannot be let slide.)

The reality is one cannot make perfect parts. But one can greatly reduce the 
consequences by making the system *tolerant* of faults. It's a different mindset.

Note that the Fukushima reactor and the Deepwater Horizon rig did not have 
backup systems. And so when something went wrong, a zipper effect resulted.

(I don't recall the details, but I went through the zipper for both of them. It 
was rather astonishing for me as redundancy and fault tolerance was hammered 
into me.)