A Philosophy of Software Design

[Forum User]

On Sunday, 28 June 2026 at 03:49:06 UTC, Walter Bright wrote:
> Yesterday, I watched an episode of "Aviation Disasters". In it, 
> the airplane had two pitot tubes for measuring airspeed. One 
> fed the airspeed indicator for the pilot, the other fed the 
> copilot's indicator.
>
> The pilot's one started behaving erratically, showing a very 
> different airspeed than the copilot's. There was no indication 
> of which one was wrong (or if both were wrong). The pilot 
> decided to trust his indicator.
>
> The result was a crash and everybody died.
>
> If the pilot's indicator said "NaN" then he'd have known which 
> one was broken.

Air France 447? They were not broken but some were clogged and
the speed returned differed. If the computer could magically
have diagnosed which of the tubes "were broken" it could have
simply excluded the "broken" from the air speed computation.