[Elecraft] K3: too easy to overwrite dial memories

[Ed Lambert]

For example, a
> (hypothetical!) button that shuts down the jet engines on an aircraft 
> requires a confirmation step... because turning off the engines until 
> the pilot hits UnDo would be bad!
> 
>    This rule applies to software as well as hardware.
> 
> -- Eric K3NA
 
This has no bearing on the current discussion but might be interesting to
some. The "button that shuts down jet engines" is protected only by the
human instinct to survive. We sit there for thousands of hours in the
cockpit and never have any impulse to move those switches to the "cutoff"
position, except during an intentional engine shutdown. (You usually have to
lift and move to get to the cutoff position; you can't brush against them
and move them.) I can only recall one case where a B767 pilot moved both
switches to the cutoff position unintentionally. He thought they were
something else I think. That event had a happy outcome. He did resort to an
"undo" procedure.

Some airplanes with overhead panel pushbutton fire switches are guarded
mechanically to avoid hitting them with your head or shoulder when you get
out of your seat. (The fire switches cut off fuel to the engine, among other
things.)

Ed Lambert KD3Y (B747-400)